Advanced Materials Design at X-ray and Neutron Facilities

RACIRI Summer school 2013:

"Advanced Materials Design at X-ray and Neutron Facilities: Soft Matter and Nano Composites"

Book of Abstract

17–25 June

Saint-Petersburg 2013

RACIRI Summer school 2013

Dr. Natalia Grigoryeva

Saint-Petersburg State University

Faculty of Physics

Saint-Petersburg, 198504, Russia

The RACIRI summer school strives for strengthening the scientific knowledge base of young researchers in advanced materials design with a strong connection to the excellent research infrastructures in the region and to contribute to the necessary interdisciplinary literacy in relevant scientific fields and disciplines.

The RACIRI summer school is a joint initiative by Sweden, Russia and Germany embedded in the collaborative frameworks of the Röntgen-Angström-Cluster (RAC) and the Ioffe-Röntgen-Institute (IRI).

Partnering organizing institutions are NRC Kurchatov Institute in Russia, DESY in Germany and the Swedish Research Council Vetenskapsradet.

RACIRI Summer school 2013: "Advanced Materials Design at X-ray and Neutron Facilities: Soft Matter and Nano Composites": Book of Abstract / Ed. N. Grigoryeva — Saint-Petersburg, publishing house "SOLO", 2013. — 98 p.p. with illustrations.

ISBN 978-5-98340-315-4


Organizers

Saint-Petersburg State University, Faculty of Physics

National Research Centre "Kurchatov Institute"

B.P. Konstantinov Petersburg Nuclear Physics Institute

Objectives

It is an important element towards a vivid Baltic science and innovation area to

harness the potential of the next generation of researchers and to fully exploit the rich

scientific infrastructure in the future.

The program structure, lectures and topics of the RACIRI summer school are designed

to improve the fundamental understanding in advanced materials design rather than

focusing on plain experimental methods and techniques. This will enable young

researchers to better tackle today’s and tomorrow’s challenges and key barriers in

materials sciences.

Location

The first RACIRI summer schol take place in the Hotel New Peterhof in the municipal

town Petergof (Russian: Петерго́ф) or Peterhof (Dutch/German for "Peter's Court") in

the district of St. Petersburg, located on the southern shore of the Gulf of Finland.

The town hosts one of two campuses of Saint Petersburg State University. A series of

palaces and gardens, laid out on the orders of Peter the Great, and sometimes called

the "Russian Versailles", is also situated there. The palace-ensemble along with the city

center is recognized as a UNESCO World Heritage Site.

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Committee

Steering Committee:

Helmut Dosch, Chairman of the Board of Directors at DESY

Mikhail Kovalchuk, Director NRC “Kurchatov Institute”

Ulf Karlsson, Head of the Swedish Delegation and Coordinator RAC, KTH Stockholm

Scientific Committee:

Russia:

Serguei Molodtsov (European XFEL and current chair of scientific commitee),

Alexander Ioffe (FZJ)

Germany:

ndreas Stierle (DESY),

Klaus Habicht (HZB)

Sweden:

Jens Birch (Linköping University),

Aleksander Matic (Chalmers U).

Local Organization Committee:

Kashkarov P.K. NRC “Kurchatov Institute”

Rychev M.V. NRC “Kurchatov Institute” / European XFEL

Altynbaev A.V. NRC “Kurchatov Institute”

Yatsyshina E.B. NRC “Kurchatov Institute”

Grigoryeva N.A. Saint-Petersburg State University

Spitsyn A.V. NRC “Kurchatov Institute”

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RACIRI Summer School-Program

Saturday, 17 August 2013

10.00–19.00 Arrival and Check in (New Peterhof Hotel, Russia, 198510, St. Petersburg, Peterhof, St. Peterburgsky Prospect, 34, Tel. + 7 (812) 319-10-10)

19.00–23.00 Welcome dinner with barbecue and beer

Sunday, 18 August 2013

12.00–13.00 Lunch

13.00–13.30 Welcome:

Helmut Dosch, Chairman of the Board of Directors of DESY Mikhail Kovalchuk, Director of NRC Kurchatov Institute Ulf Karlsson, Coordinator of RAC, KTH Stockholm

Serguei Molodtsov (European XFEL and chair of RACIRI scientific commitee)

Mikhail Rychev (European XFEL, NRC Kurchatov Institute)

13.30–14.20 Introductory lecture:

Mikhail Kovalchuk, NRC Kurchatov Institute (RU)

"Convergence of sciences and technologies: from inanimate tо living matter"

14.20–14.40 Coffee Break

Photon Sources: Facilities, technics and scientific basics

14.40–15.30 L1: Massimo Altarelli, European XFEL (DE) "From 3rd to 4th Generation Sources: X-Ray Experiments with Free-Electron Lasers"

15.30–16.20 F1: Richard Neutze, Gothenborg University (SE) "Structural and dynamical studies of proteins at an X-ray free electron laser"

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Neutron Sources: Facilities, technics and scientific basics

16.40–17.30 L2: Victor Aksenov, PNPI Gatchina (RU) "Reactor neutron sources"

17.30 –18.20 F2: Ken Andersen, ESS (SE) "Pulsed neutron sources"

19.00–20.30 Dinner

20.30–22.00 Free Time

Monday, 19 August 2013

Theory 1 (real structure related)

08.00–09.30 L3: Igor Erukhimovich, Lomonosov U Moscow (RU) "Polymer nanostructures in the bulk and under nanoconfinement: physics, scattering, applications

09.30–13.00 Summer School Cultural ProgrammePeterhof Garden

13.00–14.00 Lunch

14.00–15.30 F3: Efim Kats, Landau Institute and ILL (RU/F) "Determination of structural and physical features of colloidal systems from small angle scattering data"


Theory 2 (electronic structure related)

16.00–17.30 L4: Alexander Lichtenstein, U Hamburg (DE) "Advanced methods in electonics structure calculations"


18.00–19.30 F4: Hans Agren, KTH Stockholm (SE) "DFT calculations of X-ray spectra"

19.30–20.30 Dinner

20.30–22.00 Poster session

Tuesday, 20 August 2013

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Diffraction 1 (atomic: single crystals, powders)

08.30–10.00 L5: Jens Als-Nielsen, Riso National Laboratory (DK) "X-rays and Neutron-Fundamentals in 90 minutes"


10.30–12.00 F5: Christian Riekel, ESRF (F) "Aspects of Functional Biomaterials"

12.00–13.30 Lunch

Diffraction 2 (molecular: single molecules, polymers, colloids, etc.)

13.30–15.00 L6: Sunil Sinha, U San Diego (USA) “X-ray and Neutron scattering from surfaces of complex fluids”


15.30–17.00 F6: Sergei Chvalun, NRC Kurchatov Institute (RU) “Nanostructured polymeric and hybrid materials synthesized by VDP-process: Electronic and optoelectronic application”

19.00–20.30 Dinner

20.30–22.00 “What is…?”

Wednesday, 21 August 2013FREE DAY

08.30–13.00 Facility Tour Gatchina

13.00–14.00 Lunch

14.00–21.30 Summer School Cultural Programme

21.30–22.30 Dinner

Thursday, 22 August 2013

Imaging 1 (solid matter, domains and membranes)

08.30–10.00 L7: Carolyn Larabell, LBNL (USA) “Imaging biological specimens with X-rays”


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10.30–12.00 F7: Chris Jacobsen, APS/ANL/Northwestern U (USA) “X-ray microscopy: combining imaging and spectroscopy”

12.00–13.30 Lunch

Imaging 2 (large molecules, clusters, gels and liquids)

13.30–15.00 L8: Michael Avdeev, JINR (RU) “Structural nanodiagnostics of ferrocolloidal systems by neutron scattering”


15.30–17.00 F8: Joachim Dzubiella, HU Berlin, HZB (DE) “Theory and modeling of structural aspects and dynamics of liquids”

19.00–20.30 Dinner

20.30–22.00 Key note lecture: Paul Chaikin, New York University (USA) "Artificial Life"

Friday, 23 August 2013

Spectroscopy 1 (electronic structure related)

08.30–10.00 L9: Joachim Stöhr, SLAC (USA) “Investigation of Nanoscale Dynamics in Materials with an X-Ray Laser”


10.30–12.00 F9: Emad Flear Aziz Bekhit, HZB (DE) “Structure and dynamics of biochemical systems in solution using modern soft X-ray spectroscopy and table-top techniques“

12.00–13.30 Lunch

Spectroscopy 2 (real structure related)

13.30–15.00 L10: Michael Monkenbusch, FZJ (DE) “Dynamics of Macromolecules”


15.30–17.00 F10: Natalia Novikova, Inst. of Crystallography RAS (RU) “X-ray fluorescence methods for investigations of lipid/protein membrane models”

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19.00–20.30 Dinner

20.30–22.00 Paper presentations

Saturday, 24 August 2013

Materials Preparation 1 (crystal growth, epitaxial films, self-assembling, etc.)

08.30–10.00 L11: Alexander Vul‘, Ioffe Institute (RU) “Preparation and characterization of the new carbon nanostructures: nanodiamonds, carbon onions and graphenes”


10.20–11.50 F11: Frank Schreiber, Uni Tübingen (DE) “Growth processes and their characterisation by X-rays and neutrons”

11.50–13.00 Lunch

Materials Preparation 2 (biosamples, wet chemistry, gels, etc.)

13.00–14.30 L12: Michael Mertig, Uni Dresden (DE) “Biomimetic material synthesis”


14.50–16.20 F12: Dmitrii Gorin, Uni Saratov (RU) “Core-shell nanocomposites”

16.30–24.00 Summer School Cultural Programme

And School Dinner with Awards

Sunday, 25 August 2013

10.00–12.00 Check out and Departure

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Two aspects of my research in the field of scatteringAdlmann Franz1

1Division of Material Physics, Department of Physics and Astronomy, Uppsala University, Sweden [email protected]

In this poster two aspects of my research are presented. The first part is highlighting the properties of Pluronic F127 micelles using grazing incident neutron scattering. The crystal structure and the average lattice constant can be extracted analyzing the scattering pattern. By introducing a time of flight measurement, additional information of the ordering of the micelles in dependence of penetration depth is derived. In the second part the magnetic behavior of Palladium in presence of a small layer of iron is described. A phase

retarder is inserted in the beam of synchrotron radiation on the Palladium L3 edge. This produces an instant change of the orientation in the circularly polarized light. Hence it is possible to derive the magnetic anisotropy profile and consecutively calculate the magnetic polarization in the boundary layer. Plotting the polarization over the dimensionless temperature, the nature of the magnetic phase transition is revealed.

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Magnetic structure of MnGe in a wide temperature rangeE. V. Altynbayev1,2, S.-A. Siegfried3, N.M. Potapova1,

V. A. Dyadkin1,4, E. V. Moskvin1,2, D. Menzel5, Ch. Dewhurst6,R.A. Sadykov7,8, L.N. Fomicheva8, A.V. Tsvyashchenko8,

S. V. Grigoriev1,2

1Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, Gatchina, Russia, 188300; 2Faculty of Physics, Saint-Petersburg State University, 198504 Saint Petersburg, Russia;

3Helmholtz Zentrum Geesthacht, 21502 Geesthacht, Germany; 4Swiss-Norwegian Beamlines at the ESRF, Grenoble, 38000 France;

5Technische Universität at Braunschweig, 38106 Braunschweig, Germany; 6Institute Laue-Langevin, F-38042 Grenoble Cedex 9, France;

7Institute for Nuclear Research, RAS, 142190, Troitsk, Moscow, Russia; 8Institute for High Pressure Physics, 142190, Troitsk, Moscow Region, Russia.

Corresponding Author’s e-mail: [email protected]

INTRODUCTION The cubic B20-type compound MnGe orders below TN in a one-handed spin helical structure with a small propagation vector k ≈ 2.2 nm-1. The small-angle neutron scattering (SANS) experiments are performed to study details of the temperature evolution of the spin structure above and below TN. It is widely recognized that the magnetic structure of MnGe is built on the hierarchy of interactions: the strongest ferromagnetic exchange interaction, the antisymmetric Dzyaloshinskii-Moryia interaction, and the weakest cubic anisotropy [1, 2]. The magnetic system based on these interactions is ordered in the long period helix. The antisymmetric exchange interaction and cubic anisotropy fix the orientation of spiral along the principal axes of the cubic structure. EXPERIMENT Polycrystalline MnGe samples has been synthesized by high pressure method at the Institute for High Pressure Physics. As they can be only sinthesized under high pressure, samples are in a polycrystalline powder form crystallites with size not less than a micron (see [3] for details). The X-ray powder diffraction confirmed the B20 structure of these samples and showed traces of impurities less than 1-2% in the volume fraction. Magnetic susceptibility measurements were carried out with the

SQUID-magnetometer after cooling in zero magnetic field to T = 5 K, then heating in the magnetic field of 50 mT. SANS measurements were carried out at instrument D-11 at ILL reactor, Grenoble, France. The scattering intensity is measured upon zero field cooling from the paramagnetic state at T = 300 K to the ordered state at T = 5 K with the step of 5 K. RESULTS MnGe undergoes a complex transition from the para- to helimagnetic phase. At low temperature range the single Bragg reflection indicates a stable helimagnetic structure of this compound. The peak on the diffraction pattern is well described by Gaussian function with the width limited by the setup resolution function. With temperature increase the influence of spin excitations added to the scattering process. This phenomena leads to the transformation of the scattering profile from Gaussian into complex function that consists of Voigt and step-like functions what is well seen on the scattering picture. At high temperature range the scattering function transforms to the single Gaussian with center value equal to zero Q. This ascribed to Gaussian distribution of magnetic spirals with wavevector k approaching zero.

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REFERENCES [1] P.Bak, M.H.Jensen, J.Phys. C13, L881 (1980).

[2] I.E. Dzyaloshinskii, Zh. Exp. Teor. Fiz. 46 1420 (1964) [Sov. Phys. JETP 19, 960 (1964)]. [3] A. Tsvyashchenko, Journal of the Less Common Metals 99, 2, L9 (1984)

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Structure of the Vanadium — Doped Nd5Mo3Oy Single CrystalA.M. Antipin1, O.A. Alekseeva1, N.I. Sorokina1,

E.P. Kharitonova2, V.I. Voronkova2

1Shubnikov Institute of Crystallography, Russian Academy of Science, Moscow, Russia, 2Faculty of physics, M.V. Lomonosov Moscow State University, Russia

[email protected]; [email protected]

There is a compound with the fluorite-like structure, which is formed in the oxide system Nd2O3 — MoO3 with an oxide ratio of 5:6 (Nd5Mo3Oy). This fluorite-like structure is formed both in a reducing atmosphere and at the air [1–4]. This compound with a mixed electronic-ionic conductivity [5] is of great scientific and practical interest.

The aim of this work — a study of the structure of Nd5Mo3Oy single crystals, doped with vanadium, which were obtained by self-flux method in the oxide system at the air.

The structures of two single crystals Nd5Mo2.9V0.1Oy (I) and Nd5Mo2.76V0.24Oy (II) were studied at the XCalibur S (Oxford Diffraction) diffractometer with CCD detector at the room temperature. Data collection and processing were performed with the CrysAlis CCD and CrysAlis RED software, respectively. The structure has been refined by the least-square method, using the JANA2006 refinement program. Crystal structure of the fluorite-like Nd5Mo3O16 compound obtained at the reducing atmosphere was studied for the first time in [1], and the coexistence of molybdenum with two valences +5 and +6 was discovered. The valence state of the atoms was analyzed in details on the base of neutron-diffraction study of the isostructural Pr5Mo3O16 compound [2] and deviations of the valences from normal state was found for all the cations. The same deviations were found in the single crystal structure Nd5Mo3Oy, studied with X-rays [4]. It should be noted that no oxygen vacancies were found in the praseodymium compound and the oxygen conductivity was associated with the free oxygen in the cavities of the structure. In [4] ionic conductivity was explained by the

observed disorder of atoms in the crystal structure. In the present study it was shown that the atomic displacements found in [4] for the pure Nd5Mo3Oy compound, are kept after the doping with vanadium and the impurity atoms are located in the molybdenum positions.

The values of the activation energy were calculated on the basis of structural data and the possible migration paths of the oxygen ions were analyzed for the structures I and II. It was found that the O2 oxygen ions make the main contribution to the ionic conductivity, which is consistent with data on the occupation and disordering of the oxygen positions.

ACKNOWLEDGMENT This study was supported in part by the RFBR grant №11-03-00243а, by Department of Physical Science RAS within the Program in Support of Fundamental Research and Leading Scientific Schools (project no. NSh-2883.2012.5).

REFERENCES 1. P. Hubert, P. Michel, A. Thozet // Seances

Acad. Sci., Ser. C. 1973. V.275. P.1779. 2. J.B.Bourdet, R.Chevalier, J.P.Fournier,

R.Kohlmuller, J.Omaly // Acta cryst. 1982. B38. P.2371.

3. M.J. Martinez-Lope, J.A. Alonso, D. Sheptyakov, et al. //J. of Solid State Chemistry. 2010. V.183. P.2974.

4. O.A. Alekseeva, A.B. Gagor, A.P. Pietraszko,et al. // Z.Kristallogr. 2012.Vol. 227. No.12. Р.869.

5. Voronkova V.I., Kharitonova E.P., Belov D.A. // Solid State Ionics. 2012. V.225. P.654.

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Application of the Method of Neutron Activation Analysis forDetermination of Nanoparticles Transport Properties

in Biological Tissues in VivoА.А. Antsiferova¹

[email protected]

The growing use of nanoparticles in light and food industries, pharmacology, nutritional supplements makes us wonder about nanoparicle’s influence onto the living organism. It is already proven that most of the nanoparticles are toxic for living cells and their toxicity is higher than for macroparticles with the same chemical and crystalline structure. The fact is caused by their high penetrability and the specific uptake mechanism such as endocytosis. That’s why it is highly necessary to investigate interaction between nanoparticles and biological tissues. This investigation may include as their transport and transition inside an organism as mechanism of their interaction with living cells and toxic effects onto biological tissues. In the present work we have to stop at the first problem and our initial goal is to understand the transport properties of nanoparticles. Here we limit the objective by investigation only the nanoparticles of some metals and their oxides such as silver, aurum, titanium dioxide and zinc oxide. The choice is due to the applied techniques. Listed nanoparticles are administered orally and parenterally into digestive tract of experimental rats and mice. Further as it is supposed they “travel” with the blood flow to tissues and penetrate through some of their barriers interacting with cells and after that nanoparticles may be excreted or accumulated within tissues. The problem is to determine kinetics of their accumulation and excretion from main organs. Thus, they must be somehow traced. Chosen element compounds are able to produce long-living isotopes under proton or neutron radiation as a result of nuclear reaction with a resulting photon emission. Thus, nanoparticles of these elements may be traced by their gamma activity. This method allows us to determine integral characteristics as total concentration of

nanoparticles in each biological tissue and obtain their dependencies on time. We must distinguish chronicle, acute and sub acute ways of administration. Among other main data it has already been shown that silver nanoparticles at chronicle administration tend to accumulate within cerebrum and kidney. Behavioral tests in mice also demonstrate drastic changes in their behavior such as characteristic photophobia reduction and stress resistance increase. Aurum nanoparticles are mostly accumulated within liver. These results strongly connected to other main data may lead to understanding biophysical mechanisms of interaction between nanoparticle and the living organism and the knowledge is able to prevent humankind damage. Thus, still there is a wide open field for research. REFERENCES [1]. Lyudmila V. Zhukovaa, John Kiwib, Vitaly V. Nikandrov, “TiO2 nanoparticles suppress Escherichia coli cell division in the absence of UV irradiation in acidic conditions”, Colloids and Surfaces B: Biointerfaces 97 (2012) 240–247. [2]. Min Tua, Yi Huanga, Hai-Ling Li, Zhong-Hong Gao, “The stress caused by nitrite with titanium dioxide nanoparticles under UVA irradiation in human keratinocyte cell ”, Toxicology 299 (2012) 60–68. [3]. Sandra Gissela Marquez-Ramireza, Norma Laura Delgado-Buenrostroc, Yolanda Irasema Chirinoc, Gisela Gutierrez Iglesias, Rebeca Lopez-Marure, “Titanium dioxide nanoparticles inhibit proliferation and induce morphological changes and apoptosis in glial cells”, Toxicology 302 (2012) 146–156. [4]. Adriano A. Torranoa, Angela S. Pereiraa, Osvaldo N. Oliveira Jr. b, Ana Barros-Timmons, “Probing the interaction of oppositely

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charged gold nanoparticles with DPPG and DPPC Langmuir monolayers as cell membrane models”, Colloids and Surfaces B: Biointerfaces 108 (2013) 120–126. [5]. Falck, G.C., Lindberg, H.K., Suhonen, S., Vippola, M., Vanhala, E., Catalan, J.,

Savolainen, K., Norppa, H.,. Genotoxic effects of nanosized and fine TiO2. Hum. Exp. Toxicol. 28 (2009) 339–352.

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Industrial Applications of Synchrotron RadiationG.A. Appleby

PT-DESY, Deutsches Elektronen Synchrotron, Notkestraße 85, 22607 Hamburg, Germany [email protected]

The unique properties of synchrotron radiation makes it ideal for detecting chemical elements and environments within fluids, glasses, amorphous solids and crystalline materials making them applicable to a wide range of industrial fields. At synchrotron facilities such as DESY, MAX-Lab and BESSY, many industrial companies from a wide range of industrial category –from agriculture to nanotechnology to cosmetics to chemical companies –have had measurements and analysis performed on their materials in order to solve a specific problem or for general product development. The benefit for the company of such measurements is that they can simply deliver their samples to the laboratory and beam-scientists perform state of the art scientific measurements and analysis themselves. The measurements can be scheduled much faster than for regular academic users while the results can be made confidential, while academic users must publish all results. For the synchrotron itself, the benefits include a relatively high income (250 –750€ per hour of beamtime) as well as involvement in applied research which can be presented to the general public as easy-to-understand examples of what kind of science is being performed at these expensive and generally not well understood large research centres.

EXAMPLES OF INDUSTRIAL MEASUREMENTS In Agriculture and Food Science, analysis can be performed on trace-elements and contamination in soil, as well as to understand and slow down aging processes in foods. For Chemical companies, Understanding catalytic reactions for new catalyst development is possible as well as chemical and structural characterisation of powders, colloids and nanomaterials. In Construction and Engineering, analysis of stress, fatigue and moisture content in building materials can be made, and also testing of new alloys for automobile and aircraft components for resistance to stress, fatigue and corrosion. Environmental and Energy companies can examine the functioning and stability of solar panels and investigate low energy lightning, cooling and heating devices. For companies in Home and Personal Care, in-situ investigation at temperature dependent behaviour, stability and ageing of formulations or ingredients can be made, as well as monitoring of the effects of cosmetics on the molecular structure of skin, fingernails and hair. In Life Science and Biotechnology, drug characterisation and the development of novel pharmaceuticals is possible, as well as tomography of biomechanical components. In Material Science and Nanotechnology, Chemical and phase analysis in novel materials can be performed as well as characterisation of coatings and thin films. This poster will outline the wide variety of industrial applications of synchrotron radiation as well as providing specific examples and case studies of industrial measurements performed recently at DESY, MAX-Lab and BESSY.

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Development of the method for time resolving observation ofRocking curves by Ultrasonic Modulation

of the Lattice ParameterA.E. Blagov1, A.V. Targonsky1, P.A. Prosekov1, Yu. V. Pisarevsky1,

M.V. Kovalchuk 1,2

1A.V. Shubnikov Institute of Crystallography Russian Academy of Sciences, Leninskij prospect 59, Moscow, Russia

2 National research centre "Kurchatov institute", 1, Akademika Kurchatova pl., Moscow, 123182, Russia E-mail: [email protected]

Development of the method for measuring angular distribution of X-ray beam diffraction intensity (method for measuring X-Ray rocking curves (RC)) is represented. Intensity distribution analysis in this method is conducted by ultrasonic modulation of a lattice parameter of X-ray-acoustic crystal, used as an X-ray scheme optical element. The possibility to conduct precise time-resolved measurements of X-ray rocking curves without using sophisticated goniometry system is the distinctive feature of this method.

Special elements X-ray acoustic resonators, consisting of a piezoelectric crystal (quartz) and X-ray optical crystal (silicone) was developed to implement the method. These resonators was used to create a standing acoustic wave and effectively control a tension-compression deformation. Developed X-ray optical schemes allow us to create uniform time-variable deformation of crystal lattice inside X-ray beam footprint.

We propose several methods of RC measuring: 1,2 – use of X-ray acoustical resonator as controllable monochromator (Bragg and Laue geometry); 3,4 – application of X-ray

acoustical resonator as X-rays analyzer in Brag and Laue position.

Rocking curves, measured by proposed X-ray acoustic methods by shape and halfwidth agrees well to curves measured according to traditional way − by rotating a crystal. Experimental results of method approbation - examples of rocking curves of different reflections measured on laboratory diffractometer using X-ray acoustic method will be presented.

Experimentally achieved resolution of the method is 0.1 arcsec. Developed method and experimental schemes are totally applicable for synchrotron radiation conditions.

REFERENCES 1. Blagov A.E., Kovalchuk M.V., Kohn V.G.,

Lider V.V. Pisarevsky Yu.V. JETP 2005, 128, p893

2. Blagov A.E., Kovalchuk M.V., Kohn V.G., Pisarevsky Yu.V. Cryst. Rep. 2006, 51 p.701

3. M. V. Kovalchuk, A. V. Targonskii, A. E. Blagov, I. S. Zanaveskina and Yu. V. Pisarevskii Cryst. Rep., 2011, 56, 5, p. 828−83

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Transport properties of the La0.75Ca0.25MnO3 manganiteI.A. Bondarev1 and N.V. Volkov1,2

1Siberian Federal University, pr. Svobodny 79, Krasnoyarsk, 660041 Russia 2 Kirensky Institute of Physics, Russian Academy of Sciences, Siberian Branch,

Krasnoyarsk, 660036 Russia e-mail: [email protected]

NTRODUCTION Manganese oxides with a perovskite structure called manganites attract much attention with a great variety of effects observed in these materials, such as colossal negative magnetoresistance, metal-insulator transition, and high degree of spin polarization. Studies of the magnetotransport properties of manganites are relevant for both fundamental research and application. RESULTS AND DISCUSSION Figure 1 shows the temperature dependence of the resistance for the La0.75Ca0.25MnO3 sample in the range 80−273 K at frequencies from 1 kHz to 2 MHz in the absence of an external magnetic field and in the field H = 1000 Oe applied perpendicular to the transport current direction in the crystal. One can see that at T ≈ 170 K there are resistance maxima. The peaks are sharper in the absence of an external magnetic field; in the presence of field H, they are shifted toward higher temperatures. Figure 2 demonstrates the frequency dependence of the resistivity in the range 1 kHz−2 MHz at the temperature T = 200 K. It can be seen that with an increase in frequency the resistivity decreases. In addition, the frequency dependence is affected by applied magnetic field H, especially in the low-frequency range. CONCLUSIONS In this work, we presented the measured ac temperature and frequency dependences of the resistivity R(T) and R(ω) for the single-crystal La0.75Ca0.25MnO3 manganite in the absence of a magnetic field and in a field oriented perpendicular to the direction of the transport current in the sample.

Fig. 1. R(T) dependences in the fields (а) H = 0 and (b) H = 100 Oe.

Fig. 2. R(ω) dependences in the fields H = 0 and H = 10 kOe

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Dielectric glass-ceramics for mobile applicationsin the GHz frequency range

Hubertus Braun1,2,3, Martin Letz1, Hans-Joachim Elmers2,3,Martun Hovhannisyan1,4

1SCHOTT AG, Mainz (Germany), 2Johannes Gutenberg-Universität Mainz, Institute of condensed matter (KOMET) (Germany),

3Graduate School Materials Science in Mainz (MAINZ) (Germany), 4Tech. Universität Darmstadt, Institute of microwave engineering and photonics (Germany)

[email protected]

ABSTRACT In recent years, the continuous growth in mobile communication technologies operating in the microwave frequency range demands cost-efficient low-loss dielectric materials with sufficiently high permittivity [1]. Conventional microwave devices like antennas or filter elements which operate close to lossy materials, such as human tissue, decrease their performance due to additional dielectric losses (Body Loading effects). These effects can be prevented by using Dielectric Loading. Therefore metallised low-loss high permittivity ceramics (εr ~ 20-80) are needed which allow a high concentration of the EM near-field inside the dielectric and thereby a reduction of external influences [2]. An additional advantage of dielectric loaded devices lies in their smaller size compared to conventional pure metal devices, following the miniaturization trend of microelectronics of the last decades. In the current work, glass-ceramics in the TiO2-SiO2-B2O3-Al2O3 system are developed (εr ~ 16-32, Qf ≈ 10.000GHz, |τf | < 10 ppm/K) which have promising properties as microwave materials and offer a number of advantages in comparison to conventional sinter-ceramics. One advantage lies in the possibility to balance the τf parameter close to zero using glassy and crystalline phases (τf: relative change of resonance frequency with temperature). Materials which are obtained via a true glassy phase are relatively new in this field and are an alternative to conventional sinter-ceramic fabrication techniques [3]. Glass-ceramics are

produced in a two step process: At first, a homogeneous basic glass is casted in a conventional glass production process. Then the basic glass undergoes a temperature treatment with a defined temperature profile (< 1100°C) to initiate a controlled partial crystallization of desired paraelectric crystalline phases inside the glassy matrix (Ceramisation). Obtaining materials via a homogeneous glassy phase enables intrinsic pore free materials with comparatively superior surface properties. Additionally the effect of solid solution type doping on the dielectric properties and glass stability is investigated and the glass-ceramic materials are analyzed concerning suitability for dielectric loaded antenna applications. Comparative measurements with antennas made from commercially used sinter-ceramics are made. REFERENCES [1]: Microwave Dielectric Ceramics for Resonators and Filters in Mobile Phone Networks, I. Reaney, D. Iddles, J.Am. Ceram. Soc., 89[7]2063-2072(2006) [2]: Circularly Polarized Dielectric-Loaded Antennas: Current Technologies and Future Challenges, M. Mirsaneh, O. Leisten, B. Zalinska, I. Reaney, Adv. Funct. Mat. 2008, 18, 1-8 [3]: Bismuth Niobate Glass-ceramics for Dielectrically Loaded Microwave Antennas, M. Mirsaneh, O. Leisten, B. Zalinska, I. Reaney, Appl. of Ferroelectrics, 2008, ISAF 2008, vol.2

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Porosity Characterization of UHMWPE-derived Materials forMedical Application

Iu.Bykova 1, V.Altapova 1,3, S.Lebedev 1, T.Baumbach 2,3,I.Khlusov 1,4 and V.F. Pichugin 1

1 National Research Tomsk Polytechnic University, Lenin Ave. 30, 634050 Tomsk, Russia, 2 Institute for Photon Science and Synchrotron Radiation, KIT, 76344 Eggenstein-Leopoldshafen, Germany, 3 Laboratory for Applications of Synchrotron Radiation, KIT, 76128

Karlsruhe, Germany, 4 Siberian State Medical University, Moscow Tract 2,634050 Tomsk, Russia [email protected]

OBJECTIVE The present work contains the characterization and X-ray examination of UHMWPE materials in terms of their application in orthopedics as polymer compounds of endoprostheses for total joint arthroplasties. The possibility of 3D imaging of internal and surface geometry of weakly absorbing porous UHMWPE using synchrotron radiation phase contrast based on diffraction grating interferometer is shown. Obtained 3D images allow analyzing the structural properties of the materials: porosity, pores size, and a level of their interconnectivity. INTRODUCTION Nowadays a key component of tissue engineering approach to tissue regeneration is a concept of production of natural or artificial material that acts as a template for cells providing structural support and guiding them to the newly formed tissue [1]. To fit these functions it must have an appropriate porosity, adequate surface area and a definite three-dimensional shape. Ultra-High Molecular Weight Polyethylene (UHMWPE) is actively used material for fabrication of sliding element in biomedical application. Macro- and micropores as the defects of UHMWPE internal structure decrease its mechanical properties and increase failure rate dramatically. So, nondestructive control of polymer compounds before and after implantation is a state of art for a prognosis of prosthesis fate. Nowadays X-ray phase-contrast imaging is established and successfully developed technique for biomedical nondestructive 3D visualization of

weak-absorbing materials. X-ray phase-contrast imaging provides qualitative and quantitative information about scaffold structure in term of pore size and pore interconnectivity, also monitoring of tissue ingrowth [2]. In combination with grating interferometry (GI) it helps to achieve high phase sensitivity in a case of low detector resolution. MATERIALS AND METHODS The samples of UHMWPE and its copolymers were used in the present work. Experimental UHMWPE samples were produced by compression moulding technique. UHMWPE powder at the mould was pressed at a controlled rate (15 kN), and temperature 170C was applied to the mould using electric heated system. For fabrication of samples with a porous structure powder UHMWPE GUR4022 (Ticona LLC) were used. An average particle size is 120-150 µm, the density of the polymer is around 55 g/cm3. The formed polymers and copolymers possessed both porous and dense internal structure. The materials had a shape of round or rectangular plates with the thickness around 0.8-1 mm, that were divided into square samples of 1×1 cm2 size. It is known that phase contrast imaging enhances the contrast for the fine features within a sample. To achieve the high phase sensitivity a grating interferometry setup was applied [3]. The main elements of grating interferometer are phase-shift grating G1 and absorption grating G2. As a rule phase-shifting grating is made of not absorbing material

20


which splits an incoming wave into diffraction orders. Because of interference of diffracted beams it is possible to observe the intensity variation of wave field and self-imaging effect (Talbot effect). Self-images of grating occur on the Talbot distance that can be written as:

21p

ndn ,

where n – the Talbot order, and p = p1

effective period of resulting diffraction pattern for

2 phase-shift grating. For detection the

diffraction pattern introduced after phase-shift grating the detector with very high resolution is needed. To avoid the limitation of used detector an absorption grating G2 with the same period as the diffraction pattern (p = p2) can be used. Absorption grating is made out of a highly absorbing material with high atomic number that works as a mask for detector. After G2 propagation transferred slow oscillating Moire fringes are easily identified by low resolution detector [4].

Figure 1. Schematic view of a grating interferometer setup. Computed laminography (CL) measurements were done at the Topo-Tomo beamline at ANKA, Karlsruhe Institute of Technology, Germany. A detector system included CCD camera PCO 4000 with an effective pixel size of 2.5 µm and field of view of 10×6.7 mm2. For the CL data the angle 30 degrees was chosen. For each measurement series 2500 projection images were taken over an angular range of 360° with exposure time 20ms for one projection and scan duration was 3 hours. Darkfield (camera-specific artifacts) and flatfield (beam and gratings-related artifacts) images were taken to reduce an artifact formation during reconstruction.

RESULTS AND DISCUSSION Investigation of the 3D scaffold structure leads to further information about the volume features of materials. Images, obtained using x-ray grating interferometry CL, are displayed in figure 2 (a)–(c). It shows the results, i.e., the absorption (a), phase gradient (b), dark-field (c). Three different signals are monitored during one measurement (absorption, phase, and small angle scattering) is an undoubted advantage of the phase contrast method. The images show that pores have a rounded form with the average size around 100 µm that corresponds to the results from optical microscopy. The proposed scaffolds have shown to present a pore distribution in the range of the optimal pore sizes. The pores are interconnected and look like the agglomerates of smaller units.

Figure 2. Images of porous UHMWPE obtained using grating interferometer a) absorption b) phase-contrast c) dark-field. For the evaluation of 3D pore distribution the image processing software MAVI-Modular Algorithms for Volume Images was implemented. For 3D calculation the sample size 660×660×660 µm3 were chosen. 90% of all amount of pores are interconnected, that mean the low presence of isolated pore units, which makes them more similar to the organic cartilage or bone tissue.

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Figure 3. Pore size distribution for 3D image of UHMWPE (90 %UHMWPE (GUR4022)+10 %PVDF). The diameter of pores varies from 28 to 245 µm. Pore size distribution for 3D image showed that internal structure of porous scaffolds may be suitable for tissue engineering. Porous sample (GUR4022)+10 %PVDF) has an average diameter of pores between 60-90 µm (33%), around 21% of the pores has a diameter distribution 90-120 µm, 14% of pores are bigger than 120 µm. For example, it is considered as the sufficient pore size for implants integration with bone tissue [5]. Around 32% of pore sizes are lower than 60 µm. The porosity level is around 15 % of scaffold volume. Stem cells and other types of cells (chondroblasts, osteoblasts, etc) have real possibility to populate porous structure of tested samples. At the same time, natural cartilage has a porosity varying from 68 % to 85 % in adult joints. The pore size <100 µm and low porosity may potentially limit an access of nutrients to cells. On the other hand, decreasing the pore size improves the retention of the synthesized molecules of intercellular matrix [6].

CONCLUSION Synchrotron radiation is a powerful technique for polymeric biomaterials investigation. The image analysis obtained by grating interferometry in laminographic geometry allows non-invasive and accurate quantification of three-dimensional structure of biomaterials, helps to evaluate pore size, pore distribution, their volume and

interconnectivity. The obtained CL GI-based 3D images of polymer has a resulting voxel size 5,5 µm ×5,5 µm ×5,5 µm. It is a positive achievement to develop X-ray phase microtomography for non-destructive testing of polymer compounds of endoprostheses for total joint arthroplasties ex vivo and in vivo. On the other hand, it may be applied to select weakly absorbing porous biomaterials with optimal porosity for tissue bioengineering. A level of microtopography (porosity, roughness) has to play a determinative role in a control of cell behavior on the surface and in pores of material. Moreover, achieved geometry resolution (20-30 µm) allows hoping to visualize cells seeding and colonization in the bulk microterritories of polymer scaffold ex vivo and step by step in vivo.

REFERENCES 1 W.L. Graysona, et al (2009) Biomimetic approach to tissue engineering. Seminars in Cell & Developmental Biology 20:665–673. 2 R. Cancedda, et al (2007) Bulk and interface investigations of scaffolds and tissue-engineered bones by X-ray microtomography and X-ray microdiffraction. Biomaterials 28:2505–2524. 3 V. Altapova, et al (2011) X-ray phase-contrast radiography using a filtered white beam with a grating interferometer. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 648:S42-S45. 4 M. Żenkiewicz (2007) Methods for the calculation of surface free energy of solids. Journal of Achievements in Materials and Manufacturing Engineering 24. 5 J. S. Capes et al (2005) Fabrication of polymeric scaffolds with a controlled distribution of pores. Journal of materials science: materials in medicine 16:1069 – 1075. 6 S.Grad, et al (2004) Scaffolds for Cartilage Tissue Engineering: Effect of Pore Size. European Cells and Materials 7:1–3.

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Structure and self-organizationin magnetic liquidsHauke Carstensen, Max Wolff, Vassilios Kapaklis

Material physics, Department of Physics and Astronomy, Uppsala University [email protected]

INTRODUCTION AND APPROACH Ferrofluids are magnetic liquids that contain nanometer sized magnetite particles. They are commercially used in many different applications, e.g. in high-end loudspeakers or as liquid seals. Furthermore ferrofluids are object of present research.

We present a new route of addressing self-organization in a magnetic liquid. The basic idea behind it is that ferrofluid is used as solvent for micrometer sized ferromagnetic and diamagnetic particles. The effective magnetic behavior of the particles is altered since they replace ferrofluid in a certain volume. This effect can be seen analogue to the Archimedes principle.

The approach described above makes it possible to tune the magnetic properties of the micrometer sized particles by changing the concentration of nanometer sized particles in the solvent and thus the effective magnetic behavior of the large particles. Due to the magnetic interaction, the larger particles arrange themselves in lattices. By changing the ferrofluid concentration the magnetic susceptibility of the solvent is changed and the effective susceptibility of the larger particles is altered. Therefore the interaction between them

is tunable and different structural arrangements can be created.

RESULTS AND DISCUSSION We have studied the phase transition from cubic to hexagonal ordering while continuously increasing the magnetic susceptibility of the solvent. The positions of the particles were visualized by particle specific dyes and the use of an optical microscope. The individual particle positions were evaluated automatically and a model to quantitatively explain the results is presented.

OUTLOOK: NEUTRON SCATTERING While 2D systems can be observed by light microscopy, this is not possible for 3D systems. These systems can be analyzed by neutron scattering. Small angle scattering can provide the correlation function between the particles and therefore the structure in which the particles are ordered. Neutron scattering provides high contrast, since the colloid is water-based and can easily be deuterated to achieve high contrast. Additionally polarized neutrons can be used to investigate in the magnetic properties. Numerical simulation of the system provides a model of the structure, in which the particles are arranged. This can be used to improve the fitting of the scattering results.

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Comparative morphology of macromolecules ofImmunoglobulin-M and human Rheumatoid Factor

from SAXS dataDeniza I. Chekrygina1, Vladimir V. Volkov1, Victor A. Lapuk2,

Elena Yu. Varlamova3

1 Institute of Crystallography, Russian Academy of Sciences, 117333 Leninsky pr. 59, Moscow, Russia. 2 Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Leninsky pr. 47, Moscow, Russia

3 Hematology Research Center, Russian Academy of Medical Sciences, 125167 Novozykovsky proezd, 4a, Moscow, Russia [email protected]

STATEMENT OF PURPOSE Due to the wide spread of human immune diseases comprehensive investigations of the morphology of macromolecules of immunoglobulins and human rheumatoid factors are of high importance. Despite of the fact that atomic [1] and low-resolution structural models [2] of these macromolecules were obtained previously, the problem of structural and functional differences between these two kinds of immunnoglobulins are still unrevealed. The main purpose of this work was in the determination of structural models of immunoglobulin-M (IgM) and human rheumatoid factor (IgM-RF) from small-angle X-ray scattering (SAXS) data and clarifying the difference between shapes of the proteins.

INTRODUCTION IgM and IgM-RF are the biggest macromolecules among immunoglobulins. Up to now there is no reliable model of IgM-RF, and its structural difference from IgM is still not clear. Large molecular masses (about 900-1000 kDa) and high flexibility of the proteins make their crystallization impossible. One of the most important questions in immunology is the difference between structures of IgM and IgM-RF. In particular, it is crucial to know low-resolution shapes of IgM and IgM-RF. One of the best nondestructive methods of determination of shape models of macromolecules in solution is the small-angle X-ray scattering (SAXS). Earlier studies [2] suggested that the differences between IgM and IgM-RF should be in the peripheral Fab regions, because they contain the antigen-binding sites

responsible for the antibody function. Analysis of SAXS data in [2] allowed authors to conclude that the difference is explained by higher asymmetry of Fab-RF pairs, and, probably, by lower molecular mass of the entire IgM-RF. In the present work, the comparative structural study of IgM and IgM-RF was performed on the large set of SAXS data (previous and novel) to provide more details.

APPROACH Small-angle X-ray scattering was applied to study structural characteristics of the immunoglobulins. Experiments were done at the beamline X33 (DESY, EMBL c/o Hamburg). SAXS data processing was performed using ATSAS program package [4] and original software. The maximum diameters and radii of gyration were obtained using pair distribution functions calculated by the regularized Fourier transform program GNOM [4]. Low-resolution molecular shapes were obtained by two ab initio methods, DAMMIN [4], which employing a dummy atom (bead) model of a particle, and GASBOR [4] employing a chain-like ensemble of dummy residues. The programs fit experimental scattering intensity by a global minimization method based on simulated annealing and random search of spatial arrangement of the structural elements. The program DAMPRIS was developed to calculate radial distributions as a relative number of dummy atoms depending on their distance from the center of the model.

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Samples of the human monoclonal IgM and the rheumatoid factor IgM-RF (Waldenström’s disease) were prepared according to the procedures [3] with concentrations from 2.3 to 12.5 mg/ml.

RESULTS AND DISCUSSION The maximum diameters (Dmax) of IgM and IgMRF and radii of gyration (Rg) were estimated from pair distribution functions. According to the results, in the case of IgM samples Dmax was found to be 39-41 nm and Rg of about 12.4–12.8, while in the case of the IgM–RF the values were evaluated as 36-38 nm and Rg =10.8–11.6 nm. The typical models obtained are shown in the Figure.

Figure. Typical structure models of IgM-RF obtained from SAXS data using spherical dummy atoms by DAMMIN (a-d), model using amino-acid residues by GASBOR (e) and Perkins atomic model (PDB: 2RCJ) [1] of IgM.

For all structural models radial distribution functions were calculated using about 100 simulations obtained from 5 series of samples. Comparison of the radial distributions confirmed the conclusion about lower density and looseness of the peripheral regions of IgM-RF versus intact IgM macromolecules.

REFERENCES 1. Perkins S.J., Nealis A.S., Sutton B.J., Feinstein A. Solution Structure of Human and Mouse Immunoglobulin M by Synchrotron X-ray Scattering and Molecular Graphics

Modelling. A Possible Mechanism for Complement Activation. // J. Mol. Biol. 1991. V.221. P.1345. 2.Volkov V.V., Lapuk V.A., Kayushina R.L., Shtykova E.V., Varlamova E.Yu., Malfois M. and Svergun D.I. Low-resolution structure of immunoglobulins IgG1, IgM and rheumatoid factor IgM-RF from solution X-ray scattering data. // J.Appl.Cryst. 2003. V.36. P.503–508. 3. V. A. Lapuk, A. I. Chukhrova, E. V. Chernokhvostova, V. A. Aleshkin, G. P. German, E. Yu. Varlamova, A. M. Ponomareva, N. P. Arbatskii, and A. O. Zheltova. A simple

10 nm

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method for isolation of monoclonal immunoglobulin M with rheumatoid activity. // Biochemistry (Moscow). 1992. V.57.P.617–626.

4. Konarev P.V., Petoukhov M.V., Volkov V.V., Svergun D.I. ATSAS 2.1, a program package for small-angle scattering data analysis. // J. Appl. Crystallogr. 2006. V.39, P.277–286

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Surface modification of metal oxide nanoparticles throughcontrolled radical polymerization for improving electrical

insulation in HVDC cablesCarmen Cobo Sánchez, Martin Wåhlander, Linda Fogelström,

Anna Carlmark, Ulf Gedde, Eva Malmström1

1 KTH Royal Institute of Technology, School of Chemical Science and Engineering, Department of Fibre and Polymer Technology, SE–100 44 Stockholm, Sweden

Corresponding author: Carmen Cobo Sánchez, [email protected] Energy consumption increases daily in the world. This fact implies that new ways to produce and/or transport energy must be investigated. The development of new environmentally friendly energy sources from different parts of the globe will involve the creation of improved insulation cables to transport this energy efficiently. Following this path, new advanced materials must be developed. One of the suggested approaches is to include inorganic nanoparticles in the crosslinked polyethylene (XLPE) matrix used for high voltage direct current (HVDC) cables. These nanoparticles are intended to change the charge distributions in the matrix, reducing the possible treeing of the material, which is one of the most common defects. However, a perfect interface contact between nanoparticles and matrix is desired. Inorganic nanoparticles have a hydrophilic surface, whilst polyethylenes and other cable material are mostly hydrophobic. Due to this, surface modification of nanoparticles is often needed.

In this study, three different types of inorganic nanoparticles, zinc oxide (ZnO), aluminum oxide (Al2O3) and magnesium oxide (MgO) are modified through surface initiated atom transfer radical polymerization (SI-ATRP).

In a first step, organic initiating-containing compounds, such as silanes, phosphonic acid, dopamine and disulfide compounds are attached to the surface of the nanoparticle by covalent bonding. This addition enables the ATRP of different monomers from the nanoparticle surface. In this work, methyl methacrylate (MMA), 2-ethylhexyl acrylate (EHA) and lauryl methacrylate (LMA) are polymerized from the nanoparticles and characterized to corroborate the success of this modification. It can be seen that the degree of grafting of the nanoparticles depends on the type of nanoparticle and the quantity of organic compound added. Nevertheless, surface initiated polymerizations can be correlated between the different materials and the polymer itself, showing a potentially controlled system. Characterization is carried out through SEC, NMR, SEM, FT-IR, TGA and DLS.

In a second step, the grafted nanoparticles will be added to a polyethylene matrix and the corresponding materials will be characterized mechanically and electrically.

Figure 1. Scheme of the grafting of an Al2O3 nanoparticle with poly(methyl methacrylate) initiated with a phosphonic acid. 27


s, nm-1

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Saxs Derived 3d-Model Of The Novel Bacterial Fructose1,6-Bisphosphate Aldolase

L.A. Dadinova1, E.V. Rodina2, N.N. Vorobieba2, E.V. Shtykova1

1 A.V.Shubnikov Institute of Crystallography, RAS, Leninsky pr., 59, 119333, Moscow, Russia; 2 Lomonosov Moscow State University, Chemistry Department, Leninskie gory, 1, Bldg. 3, 119991,

Moscow, Russia STATEMENT OF PURPOSE Fructose-1,6-bisphosphate aldolases (Fba) are cytoplasmic enzymes, which play a crucial role in metabolic regulation [1]. Among different forms of aldolases, bacterial Fba (FbaB) is considered to be a new family of the enzymes. Up to now neither 3D structure nor the spatial quaternary organization of FbaB were determined. However, it is well known that interaction of FbaB with the essential cell enzyme, inorganic pyrophosphatase (PPase) leads to significant physiological consequences [2]. Thus, to analyze structural characteristics of the novel bacterial FbaB and of its complex with PPase in solution, using small-angle X-ray scattering (SAXS) and advance SAXS data interpretation methods, is an actual and important task. APPROACHES SAXS data were collected at the beamline P12 (DESY, Hamburg). Data processing was performed using ATSAS program package [3]. Low-resolution shapes of the specimens were reconstructed by ab initio method (program DAMMIN) employing annealing protocol and a dummy atom (bead) model of a particle. To run the program and to determine the maximum sizes (Dmax) of the scattering objects, distance distribution function p(r) was computed by indirect Fourier transformation and program GNOM. Method of molecular tectonics (rigid body modeling and program SASREF) was also applied to characterize the mutual arrangement of the enzyme macromolecules in the complex. To evaluate the amount of FbaB-PPase complexes formed in solution program OLIGOMER was used. RESULTS AND DISCUSSION

The results of the shape reconstruction of the individual FbaB and PPase macromolecules are shown in Fig. 1 (a & b). Bottom inserts in Figure 1 demonstrate low resolution shapes of the enzymes restored by the program

Figure1. DAMMIN and GNOM model curves, as it is clearly seen from Fig. 1 (a, b), yield good fits (curves 2 & 3, respectively) to the experimental data (curves 1) with average discrepancy 0.5. Estimated from p(r) functions (top inserts in Fig. 1) maximum sizes of FbaB and PPase were

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s, nm-1

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lg I, relative

1

2

3

4

123

r, nm

0 5 10 15 20

p(r)

024

68

1012

141618

found to be 12.4 nm and 7.8 nm, correspondingly. Further step of our study was reconstruction of low resolution shape of FbaB-PPase complex in solution. We used two approaches: ab initio protocol and rigid body modeling. Both approaches yield reconstructions of the same shapes and sizes revealing elongate body with the size of 20.3 nm. The results are shown in Fig. 2. Figure notations are analogous to those in Fig. 1.

Figure 2

The Dmax of the complex is in a good agreement with the sum of maximum sizes of each individual enzyme, confirming, thus, formation of FbaB-PPase bio-composite. Interesting, however, molecular mass (MM) of the complex in solution (260 kDa), estimated from intensity scattering at zero angle, is much lower than the sum of MM of FbaB (340 kDa) and that of PPase (130 kDa), indicating that only some part of the individual macromolecules of the specimens creates the complex. To evaluate what part of FbaB and PPase participates in the complex formation, program OLIGOMER was applied. According to the calculation only 19% of macromolecules of FbaB and PPase construct

the complex, while other part exists in solution as individual particles. Such partial complexation can be explained by the fact that even though contacts between subunits in both proteins are very tight, the proteins can dissociate in solution [2]. CONCLUSIONS During our investigation we for the first time have analyzed low resolution organization of novel bacterial FbaB emzyme, macromolecular parameters of which were unknown up to now. Moreover, for the first time formation of expected biological complex between FbaB and PPase was confirmed. However, as we found out, the complex can be formed only partially. Most of the enzymes remain in solution as single macromolecules. This phenomenon is very interesting task for further biological investigations. Nevertheless, the fact of the formation of the complex is important to elucidate an involvement of FbaB in such metabolic regulation processes as stress adaptation or “quorum sensing”. REFERENCES [1] Lorentzen, E., Pohl, E., Zwart, P., Stark, A., Russell, R.B., Knura, T., Hensel, R., Siebers, B.. Crystal structure of an archaeal class I aldolase and the evolution of (betaalpha)8 barrel proteins. J Biol Chem. 2003, 278(47), 47253-47260. [2] Rodina, E., Vorobieva, N., Kurilova, S., Mikulovich, J., Vainonen, J., Aro, E.M., Nazarova, T. Identification of new protein complexes of Escherichia coli inorganic pyrophosphatase using pull-down assay. Biochimie. 2011, 93(9), 1576-1583. [3] Svergun D. Restoring low resolution structure of biological macromolecules from solution scattering using simulated annealing. Biophys J 76:, 1999, 2879–2886

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Structural, optical and electrical properties of amorphous siliconmodified by femtosecond laser radiation

A.V. Emelyanov1,2, P.A. Forsh1,2, P.K., A.G. Kazanskii2, M.V. Khenkin2, Kashkarov1,2, P.G. Kazansky3

1 National Research Centre “Kurchatov Institute”, 123182 Moscow, Russia, 2 Lomonosov Moscow State University, Physics Department, 119991 Moscow, Russia,

3 Optoelectronics Research Centre, University of Southampton, SO17 1BJ, UK [email protected]

INTRODUCTION Laser induced crystallization of hydrogenated amorphous silicon (a-Si:H) is one of the preferred methods of microcrystalline silicon (μc-Si) thin film formation for applications in thin-film electronics and photovoltaics. Despite both nanosecond and femtosecond laser pulses can be used for a-Si:H crystallization, femtosecond laser-induced crystallization includes a non-thermal ultrafast phase transition followed by a thermal effect process which is different from rapid thermal melting and subsequent solidification made by nanosecond laser pulses [1]. Most of recent studies, devoted to femtosecond laser-induced crystallization of a-Si:H, were focused on investigation of structural properties of laser treated films. It was found that the laser treatment of a-Si:H film not only changes its internal structure (crystallization process [2]), but also significantly influences the surface of the film leading to the submicron spikes formation [3]. Additionally, a-Si:H film treated by femtosecond laser radiation in air shows down-shifter luminescent features [4]. Electrical and photoelectric properties of femtosecond laser modified a-Si:H films are studied in a less substantial extent than structure transformations, despite they are very important for optoelectronic applications of modified silicon films. In this work, we report a comprehensive study of structural, optical and electrical properties of a-Si:H films irradiated by femtosecond laser pulses. We observed that femtosecond laser irradiation resulted in non-uniform a-Si:H structure modification. Spectral dependences of absorption coefficient,

measured by constant photocurrent method, of laser treated a-Si:H films were explained in terms of hydrogen effusion and additional formation of defect states in irradiated films during the laser processing. EXPERIMENTAL 300 nm thick a-Si:H films were deposited on silica glass substrates by plasma-enhanced chemical vapour deposition (PECVD) upon the decomposition of silane (SiH4) and argon (Ar) gas mixture at the substrate temperature of 250 oC. Ultrafast laser treatment of a-Si:H films was carried out with Yb:KGW based femtosecond system (Pharos, Light Conversion Ltd.) that delivered pulses of 300 fs with repetition rate of 200 kHz and wavelength centered at 1030 nm. The laser beam was focused via the aspheric lens with a numerical aperture of 0.16. The focal plane was placed 80 µm above the sample surface in order to increase the laser irradiation area and avoid surface ablation. The laser spot had a Gaussian profile with the diameter of about 15 µm on the film surface. The samples were irradiated by continuously scanning with the translation speed of 5 mm/s. The scanning step was 2 µm. The highest laser fluence used in the experiments was 60 mJ/cm2. The laser processing was carried out in ambient air atmosphere. RESULTS AND DISCUSSION Atomic force microscopy (AFM) images have shown that surface submicron size spikes have been created upon laser treatment. The spikes are formed into stripes along the direction of laser beam scanning. The stripes are spaced from each

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other roughly by 2 μm matching the scanning step of the laser beam used for the film treatment. AFM measurements of film surface profiles revealed spikes with heights of 15 –40 nm formed after laser irradiation with the fluences of 30 –60 mJ/cm2. Several processes have been identified which influence the surface structure of amorphous silicon film, crystallized by laser irradiation: hydrogen out-diffusion from a-Si:H, multiple shot crystallization, differences in latent heat and thermal conductivity between crystalline and amorphous silicon, and ambient condition of the irradiation atmosphere [5]. Explosive evaporation of hydrogen is expected to be the main reason for surface structures to occur [1, 5]. The crystalline volume fraction in silicon films under study was determined from Raman spectra analysis. A pronounced peak near ωA = 480 cm-1 is observed clearly on spectra of all samples. The peak corresponds to the amorphous silicon transverse-optical (TO) vibration mode. Another peak observed around ωC = 520 cm-1, corresponding to the crystalline silicon TO mode, appears on the Raman spectra for the samples treated with the laser fluences above 50 mJ/cm2. The integrated intensity of the peaks around 480 and 520 cm-1 were measured to estimate the crystalline volume fraction fC in studied films. While increasing laser fluence crystalline volume fraction grows, reaching the maximal value of about 36 %. The Raman peak observed around 625 cm-1 is due to presence of hydrogen in the film and corresponds to wagging vibration of Si-H bonds [6]. We used this peak to estimate the change of H concentration in our films after laser treatment. Structural changes caused by femtosecond laser treatment of a-Si:H films led to changes in their electrical and photoelectric properties. Dark conductivity was found to increase dramatically by 6 –7 orders of magnitude for the sample treated with the laser fluence of 50 mJ/cm2. It is known that dark conductivity of μc-Si exceeds that of a-Si:H by 4 –6 orders of magnitude. So the abrupt increase of the dark conductivity could be explained by increase of nanocrystalline part of the film contribution to charge carriers

transport path through the film. As to photoconductivity, it increased slightly for the films treated with higher laser fluences and reaches the maximum value for the film with 13.4 % crystallinity (treated with laser fluence 50 mJ/cm2). Some decrease of photoconductivity for the film treated at higher fluence is most likely connected with macroscopic defects formation in the treated film due to the processes of spallation and hydrogen out-effusion. Spectral dependences of absorption coefficient αCPM(hυ) were obtained by the constant photocurrent method. For all treated films the shape of αCPM(hυ) corresponds to that of hydrogenated amorphous silicon: exponential rise in the range of photon energies 1.4 eV < hυ < 1.8 eV, which is attributed to optical transitions from bands tails states, and so called “absorption shoulder” at hυ < 1.4 eV, which is attributed to transitions from defect (dangling bonds) states to conduction band. CONCLUSIONS Structural, optical, electrical and photoelectric properties of a-Si:H films modified by ultrafast infrared laser radiation were investigated. By means of AFM measurements it was observed that femtosecond laser irradiation resulted in non-uniform a-Si:H structure modification. From Raman investigations the levels of crystalline volume fraction and relative hydrogen content in studied films were estimated. The dark conductivity of femtosecond laser treated a-Si:H films was found to increase by about 6 orders of magnitude compared to pristine a-Si:H, which was associated with appearance of nanocrystalline part contribution to charge carriers transport path through the film. ACKNOWLEDGEMENTS This work was supported by the Russian Foundation for basic Research (project 12-02-33033). REFERENCES [1] T.Y. Choi, D.J. Hwang, C.P. Grigoropoulos, Opt. Eng. 42 (2003) 3383.

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[2] S. Ryu, I. Gruber, C.P. Grigoropoulos, et al. Thin Solid Films 520 (2012) 6724. [3] B.K. Nayak, M.C. Gupta, Appl. Phys. A 89 (2007) 663. [4] A.V. Emelyanov, A.G. Kazanskii, M.V. Khenkin, et al., Appl. Phys. Lett. 101 (2012) 081902.

[5] A.A.D.T. Adikaari, S.R.P. Silva, J. Appl. Phys. 97 (2005) 114305. [6] N.M. Liao, W. Li, Y.D. Jiang, et al., Appl. Phys. A 91 (2008) 349.

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Structure of Luminescent Gluconacetobacter xylinus CelluloseNanocomposites investigated by small angle scattering

Ezdakova K1, Kopitsa G.1, Smyslov R.2, Bugrov A.2, Nekrasova T.2,Khripunov A.2 , Angelov B.3 Pipich V.4, Szekely N.4

1 Petersburg Nuclear Physics Institute NRC KI, 2 Institute of Macromolecular Compounds RAS, Russia,

3 Institute of Macromolecular Chemistry, Czech Republic, 4 Heinz-Maier-Leibnitz Zentrum, Germany

[email protected]

INTRODUCTION The most perspective materials for modern nanotechnologies are the biodegradable, safe materials produced from cheap renewable natural sources. All these basic conditions are met by cellulose, which can be derived from an evolutionarily different sources such as land plants, algae, and cellulose produced by bacteria or animals. At present, the cellulose structure of different evolutionary origin is actively studied. Nano-gel films of bacterial cellulose by Gluconacetobacter xylinus (CGx) are widely used as a template for a variety of organic-inorganic composites. Known CGx based composites contain nanoparticles of silver, gold, selenium, TiO2, SiO2, CdSe, calcium phosphate, and fractions shungite [1-4]. Features of the supramolecular organization of CGx, include a grid structure formed by nanoscale ribbons, and a presence of nanochannels between neighboring nanofibrils in these ribbons formed during the biosynthesis of cellulose matrix. This supramolecular organization possesses unique sorption properties. The CGx ability to absorb various low-and high-molecular organic compounds, and inorganic nano-fillers in the form of a gel film, and in the form of suspensions (in water, ethanol, toluene, etc.) makes it a promising material for the creation of hybrid materials. It can be widely used in medicine (for example, to create a multipurpose wound covering, a precursor of bone, cartilage, etc.), membrane technology, and various fields of optoelectronics. In this work the mesostructure of nanocomposites based on

Gluconacetobacter xylinus Cellulose (strain VKM V-880 was used) is studied by complementary methods of neutron and X-ray small angle scattering. The influence of doped components, like Tb3+, nanoparticles of zirconium dioxide, on the structural properties is investigated. APPROACH Composites on the basis of CGx with ZrO2 nano particles including luminescent markers were synthesized for the first time. In our case, Tb3+ ions as low-molecular salt TbCl3×6H2O or in a complex with polymer-ligands were used as the fluorescent markers. The luminescence spectra were measured on an LS- 100 (PTI®, Canada) spectrofluorometer. The choice of the excitation wavelength of 230 or 300 nm was based on the luminescence excitation spectra of the metal-polymer complex (MPC). The spectral width of the slit of the excitation and emission monochromators was 4 nm. The SANS experiment was performed at the KWS-2 scattering facility of FRM-II research reactor using neutrons with the wavelength = 4.55 Å (/=0.01). The range of momentum transfer 3·10-3 < q < 0.43 Å-1 was obtained using three sample-to-detector distances (2, 8 and 20 m). The USANS was performed at the KWS-3 scattering facility of FRM-II research reactor using neutrons with the wavelength = 12 Å (/=0.2). The range of momentum transfer 1.6·10-4 < q < 3.5·10-2 Å-1 was obtained using

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two sample-to-detector distances (1 and 10 m). The measured data were calibrated by the incoherent scattering of plexiglass and corrected for the sample transmission, background scattering (from the quartz cell) and detector response. The resulted data were processed by the software QtiKWS. Resulting 2D isotropic spectra were averaged azimuthally. All measurements were done at room temperature. The SAXS experiment was performed at the SAXS facility at IMC in Prague (Czech Republic) using a pinhole camera (Molecular Metrology SAXS System) attached to a microfocused X-ray beam generator (Osmic MicroMax 002) with the wavelength λ = 1.54Å. The camera was equipped with a multiwire gas-filled area detector with an active area diameter of 20 cm (Gabriel design). The range of momentum transfer 0.005 < q < 1 Å-1 was obtained using two sample-to-detector distances 418 and 2254 mm. The scattering intensities were put on absolute scale using a glassy carbon standard. Resulting 2D isotropic spectra were averaged azimuthally. All measurements were done at room temperature and in vacuum. RESULTS AND DISCUSSION The hybrid polymer-inorganic biosystem on the basis of bacterial cellulose with Tb(III) has beenstudied by luminescent methods. The content of the lanthanide and ZrO2 nanoparticles has been varied in a systematic way. It is shown that changing the amount of TB(III) salt into the metal-polymeric complex lead to a drastic increase of the luminescent intensity of the hybrid systems. Besides, using nanoparticles of ZrO2, as dopants in the hybrid system of bacterial cellulose, lead to sesquialteral increasing of luminescent intensity. The data from SANS and SAXS demonstrate a behavior of the scattering curves that is typical for scattering of systems with complex multilevel structure [5]. In such structure, large particles are formed by smaller size particles or systems consisting of a few heterogeneities with different size. The following features of the

nanocomposite structure have been established from the analysis of the small-angle scattering data: 1. It has been determined that the CGx at the mesoscopic scale is a system with two-level fractal structure. The first level of the primary particles are formed with a characteristic size Dc1 = 8 nm, and develop a fractal surface with a dimension Ds1 = 2.37. On the second level the structure is formed also by a type of a fractal surface with Ds2 = 2.93. 2. It has been revealed that the addition of Tb3+ ions hardly changes the fractal dimension of the Ds1 primary particles. At the same time, their size increase significantly. Thus, in case of doping CGx with Tb3+ ions using low molecular weight salt TbCl3 × 6H2O, Dc1 characteristic dimension increases to 10 nm. In addition, Tb3+ ions that are complexed with a polymeric ligand lead to a dramatic increase of Dc1 to 20 nm. 3. It has been found that the introduction of ZrO2 nanoparticles causes significant change in the local structure of the primary particle. CONCLUSIONS In this work the mesostructure of nanocomposites based on CGx has been investigated by USANS, SANS and SAXS methods. The evolution of the structure of CGx composites has been traced in dependence on dopants type. REFERENCES 1. Maria L.C.S., Santos A.L.C., Oliveira P.C., et al. // Materials Letters. 2009. V.63. p. 797-799 2. Wang W., Zhang T.J., Zhang D.W., et al. //Talanta. 2011. V.84. p. 71-77 3. Gutierrez J., Tercjak A., Algar I., et al. // Journal of Colloid and Interface Science. 2012. V.377 p. 88-93 4. Yang Z., Chen S., Hu W. et al. // Carbohydrate Polymers. 2012. V.88. P. 173-178 5.G. Beaucage and D.W. Schaefer, J. Non-Cryst. Solids 172 –174 (1994) 797.

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Orientational ordering and packing effects of spindle shapedparticles investigated by spatially resolved coherent SAXS

B. Fischer 1,2, C.Gutt 1,2, J. Wagner 3, F. Lehmkühler 1,2, C. Passow 3,M. Sprung 1,G. Grübel12,

1Deutsches Elektronen Synchrotron DESY, Hamburg, Germany , 2 The Hamburg Centre for Ultrafast Imaging CUI, Hamburg, Germany, 3Chemie, University of Rostock, Rostock, Germany

[email protected] Hard spheres systems are often used as model system because their phase diagram only depends on the volume fraction (Royall et al. 2013, Pusey 1991). In particular such a system can mimic the properties of the liquid state (Kirkwood & Boggs 1942, Widom 1967, Weeks et al. 1971) within an accessible experimental window of temporal and spatial resolution. During the last 30 years also anisotropic elongated particles have been synthesized with a low polydispersity, such as hematite (Ozaki 1984), silica (Kuijk et al. 2011) or PMMA particles (Keville et al. 1991, Ho et al. 1993). Such anisotropic particles show an even more complicated phase diagram compared to hard spheres. Additional phases like the smectic and nematic phases appear (Vroege and Lekkerkerker 1992, Glotzer & Solomon 2007). Here the phase diagram depends not only on the volume fraction, but also on the shape and the aspect ratio of the particles (Kuijk et al. 2012). While their static structure has been intensively studied in the past (e.g. Kuijk et al 2012, Mukhija & Solomon 2011), the dynamics of the anisotropic particles has not been completely understood yet, only a few studies for the dilute regime and concentrated regime exist (Reufer et al. 2012, Wagner et al. 2013, Kuijk et al. 2012). In this study we use a centrifugal field to achieve a volume gradient of spindel-shaped particles, in which an isotropic-nematic phase transition occurs. Afterwards the preferred orientation of the particles is studied as a function of the concentration and of the confinement due to the capillary wall by means of small angle (coherent) x-ray scattering.

Hematite particles (α-Fe2O3) were prepared using a modified controlled precipitation method of ferric chloride solution which was first described by Ozaki et al. (1984). A solution of 0.02 M ferric chlorid solution containing sodium di-hydrogen-phosphate (NaH2PO4) ranging from 1.0 to 4.5×10−4 M was refluxed for 48 hours. The axial ratio between the long and the short axis of the spindles increases with the amount of NaH2PO4 (Märkert et al. 2011, Sugimoto et al. 1998). The coherent small angle X-ray scattering experiment was carried out at the beamline P10@Petra III at the Deutsches Elektronen-Synchrotron (DESY) in Hamburg (Germany). For the experiment a high heat load monochromator was used (Si-111) to set the energy of the incident beam to 7.0 keV. To investigate the influence of the confinement due to the capillary wall the sample was measured at different distances to the capillary wall in the dilute regime at a concentration about �=0.144 and concentrated regime with �=0.187.

In the dilute phase the anisotropic particles are almost completely randomly oriented in the middle of the capillary. Closer to the wall the particles start to orientate. In the concentrated phase the particles are stronger horizontally pre-aligned than in the dilute regime in the middle of the capillary. Here still some isotropic background from randomly oriented particles or domains can be seen in the pattern.

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Furthermore, the order increases with higher concentration. REFERENCES Glotzer, S.C., and Solomon, M.J., (2007) Nature 6, 557-562. Ho, C.C., Keller, A., Odell, J.A., and Ottewill, R.H., (1993) Colloid Polym. Sci. 271, 469-479. Kirkwood, J.G., and Boggs, E.M., (1942) J. Chem. Phys. 10, 394-402. Kuijk, A., Byelov, D. V., Petukhov,A. V., van Blaaderen, A., and Imhof., A. (2012). Faraday Dosciss. 159, 181-199. Keville, K. M. Franses, E. I., and Caruthers, J. M., (1991) J. Coll. Int. Sci., 144 103 -126 Kuijk, A., van Blaaderen, A., and Imhof.,A. (2011). J. Am. Chem. Soc. 133, 2346-2349. Märkert C., Fischer, B., and Wagner, J., (2011) J. Appl. Cryst. 44, 441-447. Mukhija D., and Solomon M.J., (2011) Soft Matter 7, 540-545.

Ozaki, M., Kratohvil, S., and Matijević, E., J. Col. Int. Sci., 1984. Pusey, P.N. (1991) in Liqudis, Freezing and the Glass Transition J.P.Hansen, D. Levesque and J. Zinn-Justin, Elsevier 765-942. Reufer, M.,. Martinez, V.A. Schurtenberger, P., and Poon, W.C.K. (2012) Langmuir 28, 4618-4624. Royall, C.P., Poon, W.C.K., and Weeks, E. (2013) Soft Matter 9 17-27. Sugimoto, T., Wang, Y., Itoh, H., and Muramatsu, A., (1998) Colloids Surfaces A 134,265-279 Vroege, G.J. and Lekkerkerker, H.N.W., (1992) Rep. Prog. Phys. 55, 1241-1309. Wagner, J., Märkert, C., Fischer, B., and Müller, L., (2013) Phys. Rev. Lett. 110, 048301. Widom, B., (1992) Science 157, 375-382. Weeks, J.D., Chandler, D., and Andersen, C. (1971) J. Chem. Phys. 54, 5237-5247.

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Highly ordered molecular materials studied by synchrotrontechniques

Stefan Fischer, Josef Hirte, Bert Nickel11Ludwig-Maximilians-Universität,

Geschwister-Scholl-Platz 1, D-80539 München, Germany, Fakultät für Physik and CeNS [email protected]

Increasing the efficiency of organic electronic devices such as organic solar cells requires the understanding and tailoring of interfaces. Although the structure and morphology of interfaces is subject to thorough studies, their impact on electronic processes has not been fully comprehended. A bilayer of pentacene and C60 was used as model system because both molecules are well known and frequently used in all types of organic electronics. Nevertheless the detailed structure of this configuration was still not fully identified. Atomic force microscopy (AFM) and grazing incidence wide angle x-ray scattering (GIWAXS) measurements were performed in order to get an insight in morphology and structure of both layers.

Figure 1: GIWAXS map of pentacene and C60 We show that C60 retraces the pyramid like morphology of the underlying pentacene and both molecules show crystalline growth.

Pentacene has the well known thin film phase perpendicular to the surface [00L] [1] and C60 grows in an FCC structure in [111] direction which can easily get mixed up with an hcp structure in reflectometry measurements, but the GIWAXS map, shown in figure 1, could clearly exclude that. Electronic measurements with an ambipolar device show the interface charging between both layers, but they exceeded the scope of this poster and can be found in the literature [2]. The second part of the poster treats systems of ordered lipid structures. We prepared an inverted hexagonal phase of lipids on a silicon wafer which was identified with a GISAXS measurement. We built a humidity chamber with two different lights in order to get full control over the ambient conditions. We use photo switchable molecules in combination with lipids. These molecules shall control the phase via the light in the chamber. Another project is to reveal how a lipid membrane covers Au dots on a surface. Lohmüller et al. [3] assembled Au nanoparticles in a hexagonal lattice with a lipid bilayer on top. The question of how the membrane arranges at the position of the Au remains unclear. That is why we performed a GISAXS measurement in order to reveal the formation of the lipid membrane on top of the nanoparticles. REFERENCES [1] Schiefer, S., M. Huth, et al., (2007). J. Amer. Chem. Soc. 129(34) 10316. [2] Noever, S. J., S. Fischer et al., (2013). Adv. Mat. 25(15)2147-2151. [3] Lohmuller, T., S. Triffo, et al., (2011). Nano Lett. 11(11): 4912-4918.

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Spectrometer for hard XFEL based on diffraction focusingO. Y. Gorobtsov1,2, V. G. Kohn1 and I. A. Vartanyants2,3

1National Research Center ‘Kurchatov Institute’, Kurchatov Square 1, 123182 Moscow, Russia 2Deutsches Electronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany

3National Research Nuclear University, ‘MEPhI’, 115409 Moscow, Russia [email protected], [email protected]

Development and construction of hard X-ray free electron lasers (XFELs) arises the need for high-resolution spectrometers able to resolve fine features of FEL individual pulses, that change chaotically from pulse to pulse. Those pulses have a fine structure of a typical size of ΔE/E≈10-6 (for European XFEL). In the theoretical paper [1] it was shown that it is possible to make a spectrometer that is able to resolve these features using just a plane crystal plate of appropriate thickness. This is achievable due to dynamical diffraction focusing effect [2,3]. A sketch of the setup is presented in Fig. 1.

Figure 1: Schematic view of the beamline with the diffraction focusing spectrometer. The incoming divergent beam from a secondary source is focused by a single-crystal plate at each energy near the Bragg angle. Since the Bragg angle depends on the energy, X-rays with different energies will be focused at different points just behind the crystal under conditions of focusing. In order to achieve high resolution, the effective size of the secondary source should be decreased to about a few micrometers and the angular divergence of the beam increased to the necessary value. This can be done, for example, by positioning compound refractive lenses

(CRLs) upstream from the diffraction focusing spectrometer (DFS). Fig. 2 shows intensity at the detector position (b) from a simulated XFEL pulse (a). Fine features of the pulse, visible in Fig. 2, (a) are clearly resolved at the detector position.

Figure 2: (a) Simulated XFEL spectrum with an incoming photon energy of 12.4 keV, pulse duration T = 100 fs and spectral width ΔE/E≈10-3. (b) Corresponding intensity distribution at the detector after 220 diffraction of this pulse from a Si crystal. Insets show an enlarged part of the spectrum.

REFERENCES [1] V. G. Kohn, O. Y. Gorobtsov & I. A. Vartanyants, J. Synchrotron Rad. 20, 258-265 (2013). [2] Kohn V.G., et al., Phys. Status Solidi B, 222, 407–423 (2000). [3] Afanas’ev, A. M. & Kohn, V. G. (1971). Acta Cryst. A27, 421–4

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EXAFS and XRD studies of Ti50Ni25Cu25 shape memory alloy at themartensitic transformation

Alexey Menushenkov1, Olga Grishina1, Alexander Shelyakov,Alexander Yaroslavtsev, Nikolay Sitnikov1, Yan Zubavichus2,

Alexey Veligzhanin2,Joseph Bednarcik3, Roman Chernikov3

1National Research Nuclear University MEPhI, Kashirskoe shosse 31, Moscow 115409, Russia, 2Russian Research Centre ”Kurchatov Institute”, Academic Kurchatov square 1, Moscow 123182, Russia,

3 HASYLAB at DESY, Notkestrasse 85, D-22603 Hamburg, Germany. [email protected]

INTRODUCTION TiNi-based alloys are some of the most widespread shape memory alloys (SMA). While being heated they are able to fully restore their pre-deformation shape as a result of reverse martensitic transformation (MT). Under such a behavior these alloys demonstrate considerable mechanical force. Due to their unique properties SMAs are of great interest to find the unusual ways in development of various important technical applications [1-2]. Direct and reverse MTs occur in their own temperature ranges, therefore the material demonstrates hysteretic properties under phase transformation. Characteristic temperatures of MT depend on the alloys chemical composition, production method and thermo-mechanical treatment. The demand of micro- and nano-devices construction drives the design of new types of SMA as well as the exploration of local atomic rearrangement in alloys upon MT. In present work we investigated the features of crystal structure and local environment in ternary Ti50Ni25Cu25 SMA by means of X-ray diffraction (XRD) and extended X-ray absorption fine structure spectroscopy (EXAFS) on synchrotron radiation. APPROACH In initial state the samples of three-component SMA Ti50Ni25Cu25 were thin ribbons obtained by components melt extrusion from the quartz crucible through the thin nozzle on the surface of rotating copper disk, where the sample’s solidification took place with the rate of 106K/sec. The thickness of the initial amorphous ribbons was 40−45μm, the average size of

grains was 300÷500nm. Samples were crystallized by isotropic annealing in the air at 500oC for 4 min. According to differential calorimetry study the critical temperatures of direct and revers MT were: Аs=53оС, Аf=65оС и Мs=57оС Мf=46оС (where Аs and Аf are the temperatures of austenitic transformation start and finish, Мs and Мf –temperatures of martensitic transformation start and finish). The XRD patterns of Ti50Ni25Cu25 sample were obtained at beamline BW5 of DORIS-III storage ring, HASYLAB (DESY, Hamburg) in temperature range 29-78ºC. High-energy photons with energy 100 keV of synchrotron radiation source provide several advantages: high resolution in real space due to the wide range of scattering vector, smaller correction terms (especially for absorption correction. The EXAFS spectra were measured in transmission mode above K-Ni (8333 eV) and K-Cu (8979 eV) absorption edges at STM beamline of Kurchatov synchrotron radiation source (Moscow, Russia). The EXAFS spectra above K-Ti (4966 eV) absorption edge at beamline A1 of DORIS-III storage ring (HASYLAB, DESY, Hamburg). Series of measurements were carried out upon consistent heating and cooling in the temperature ranges of direct and reverse MTs. The fitting of EXAFS spectra was performed using VIPER [3]. RESULTS AND DISCUSSION XRD results demonstrate that Ti50Ni25Cu25 alloy has the B2 type structure in austenitic (high temperature) phase and B19 in martensitic phase. Coordinates of Cu and Ni atoms in the

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unit cell were assumed to be equal. The results are in good agreement with other investigations of TiNi-Cu alloys [2,4]. Analysis of EXAFS spectra allowed us to trace the local atomic displacements upon MT and observe some discrepancies in the short and long range order data. The average bond lengths Ni-Ni and Ni-Cu differ on the local level while for the undistorted cubic configuration of austenitic phase these distances should be equal. Moreover, the atomic displacement in the first Ni coordination shell (characterized by Debye-Waller factor σ2) is one and a half bigger than the σ2 value for Cu first coordination shell. The average Cu-Ti bond length in austenitic and martensitic phases coincides with the values obtained from XRD study within the error. In a similar manner the analysis of K-Ti EXAFS-spectra revealed the 0.1 Å discrepancy of Ti-Ni and Ti-Cu interatomic distances. The EXAFS data analysis shows that in the martensitic as in austenitic phase Ti-Ni bonds have the highest disorder characterized by the Debye-Waller factor σ2 (both from K-Ti and K-Ni spectra). This indicates the dispersal of Ti-Ni bond distances in entire temperature range of the direct and reverse MT. Therefore, Ti atoms have the highest degree of mobility upon local displacements relative to Ni atoms. At the same time the local structure around Cu atoms remains almost unchangeable and is characterized by the least degree of disorder (the value of σ2 is considerably smaller). In another words, the sublattice around Cu atoms has the largest degree of stability and the least displacement amplitude. The results of EXAFS-spectroscopy reflect anomalies related to the martensitic transformation, such as unequal local shifts for different types of atoms. Such distortions of the local crystal structure of the alloy may be a kind of structural embryos and play the role of possible physical centers of martensitic nucleation. Besides, they may induce the lowering of the lattice symmetry during MT, whereby a phase transition from austenite to martensite may start earlier, i.e. at higher temperatures.

CONCLUSIONS The analysis of the EXAFS-spectroscopy data shows that in the whole temperature range of MT the bonds involving Ni atoms have the highest degree of disorder characterized by the value of the Debye-Waller factor σ2. Consequently, Ti atoms show greater mobility in respect to the local displacements relative to Ni atoms, which are the source of instability, while the local structure around Cu atoms remains almost unchanged and has the lowest disorder. The change in the local environment around Ni atoms is responsible for the occurrence of the shape memory effect in the initial TiNi alloy as in ternary Ti50Ni25Cu25

alloy. Cu atoms occupy the normal positions in the crystallographic structure and have the lowest displacement amplitude. Thus, the introduction of Cu into TiNi alloy contributes to the stabilization of both phases and influences the characteristic temperatures and MT hysteresis value by decreasing the relative amount of nickel, the change of local environment around which is responsible for the origin of martensitic transformation in alloy. Apparently, this is related to the experimentally observed sharp decline of the shape memory effect in the ternary alloy when the copper content is more than 28 at.%[5]. ACKNOWLEDGMENT This work is partly supported by Russian Foundation for Basic Researches (grants 11-02-01174-a and 12-07-00811-a). REFERENCES [1] Y. Fu, H. Du, W. Huang et al., Sensors and Actuators A: Physical 112 (2004) 395 –408. [2] H. Rösner, P. Schloßmacher, A. Shelyakov, et al., Acta Materialia 49 (2001) 1541–1548. [3] K.V. Klementev, Journal of Physics D: Applied Physics 34 (2001) 209. [4] P.L. Potapov, S.E. Kulkova, A.V. Shelyakov et al., J. Phys. IV France 112(2003)727-730. [5] N. Matveeva, Y.K. Kovneristyy, L.A. Matlakhova, et al. USSR Academy of science. Izv. Ser. Metally 4 (1987)97–100.

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Combined electrical and grazing incidence X-raymeasurements of Poly(3-hexylthiophene) thin film formation

Linda Grodd1, Ullrich Pietsch1, Souren Grigorian1

1Department of Physics, University of Siegen, Germany [email protected]

OJECTIVE We present time resolved in-situ grazing incidence X-ray diffraction (GIXD) studies of poly(3-hexylthiophene) (P3HT) film formation with simultaneous conductivity measurements for direct correlation of structural and electrical properties. This is important for understanding the charge transport mechanism and the major influencing parameters. INTRODUCTION During the past decades organic electronics has become a field of intense research with a wide range of applications such as organic photovoltaic (OPV), organic light emitting diodes (OLEDs) or organic field effect transistors (OFETs). Easy solution processing with possibilities of covering large areas, usage of flexible substrates and inkjet printing makes conjugated polymers a versatile, low cost alternative to their rigid inorganic counterparts. Among the conjugated polymers the well-known semi crystalline P3HT, which forms lamellar structures embedded in an amorphous matrix, provides rather good carrier mobility. At present, however, the conductivity and charge carrier mobility of most conjugated polymers including P3HT remains well below the ones of inorganic semiconductors. Several studies showed a strong influence of crystallinity and orientation on electrical properties (see e.g. [1] — [4]). Considerable progress in enhancement of the electrical performance of organic semiconductors requires better understanding of the underlying processes. EXPERIMENTAL APPROACH A series of in-situ GIXD experiments during film casting of P3HT from solutions with different solvents (chloroform, toluene, p-

xylene) and simultaneous conductivity measure-

Figure 1: Experimental setup for in-situ GIXD and electrical measurements

ments were performed. For this purpose, in-situ droplet analysis chamber (IDA) allowing for motor controlled deposition of the polymer solution on the Si/SiO2 substrate with source/drain gold electrodes under inert gas atmosphere was constructed. The source/drain current was recorded with a Keithley 2600 sourcemeter. X-ray measurements were done at BL9 DELTA (Dortmund, Germany) and beamline P08 PETRA III (Hamburg, Germany) using photon energies of 12.38 keV and 15 keV respectively. RESULTS AND DISCUSSION In the first series of in-situ measurements with highly volatile chloroform as a solvent we observed a complex current-structure behavior with a typical time delay (depending on the droplet size) of the structural (100) peak with respect to the maximal current. This suggests that in the case of fast solidification process highest conductivity is achieved in the transition phase from liquid to solid [5].

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The less volatile solvents toluene and p-xylene, on the other hand, showed reverse behavior with the structural peak being fully developed before the maximum current. The time delay increases with boiling point of the solvent. CONCLUSIONS By in-situ GIXD measurements we observed a complex structure-conductivity relationship with a shift between the maximum of conductivity and the fully developed structural peak depending on the choice of solvent. It supports that the overall network connection of the molecules plays an important role in charge transport. ACKNOWLEDGMENTS The authors that the beamline scientists and engineers of beamline BL9 DELTA (Dortmund, Germany) and beamline P08 PETRA III (Hamburg, Germany) for support during beam

times and BMBF, project no. 05K10PSC, for funding. REFERENCES

[1] L. H. Jimison, M. F. Toney, I. McCulloch, Martin Heeney, Alberto Salleo, Adv. Mater. 2009, 21, 16, 1568–1572

[2] R. J. Kline, M. D. McGehee, E. N. Kadnikova, J. Liu, J. M. J. Fréchet, M. F. Toney, Macromolecules 2005, 38, 3312-3319

[3] R. J. Kline, M. D. McGehee, M. F. Toney, Nature Materials 2006, 5, 222 – 228

[4] F. S. U. Fischer, K. Tremel, M. Sommer, E. J. C. Crossland, S. Ludwigs, Nano-scale 2012, 4, 2138-2144

[5] L. Grodd, U. Pietsch, S. Grigorian, Macromol. Rapid Commun. 2012, 33, 1765−1769

42


Thermotropic phase transitions in model lipid membranes basedon ceramide 6: pH influence

A.Yu. Gruzinov1, M.A.Kiselev2, E.V. Ermakova2, A.V. Zabelin1

1National Research Center “Kurchatov Institute”, Moscow, Russia 2 Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia

[email protected]

The outermost layer of mammalian epidermis –stratum corneum (SC) –plays an important role in barrier functions for different external substances trough skin and for maintaining body water balance. SC could be viewed as a number of keratinized dead cells embedded into extracellular lipid matrix which is a mixture of ceramides, free fatty acids, cholesterol and its derivatives. Typical depth of this layer is about 15-25 µm. Nowadays it’s widely accepted that barrier functions of SC are mainly due to extracellular matrix. Model systems are widely used to mimic main properties of stratum corneum in order to control components and due to a relatively easy way of preparing. We investigate four components model lipid matrix which consists of synthesized components dissolved in excess of water. Lipid molecules in water self-assembles into hollow spheric-like structures (vesicles). Its walls form a two-dimentional smectic liquid crystal. In order to investigate this soft-matter systems with low scattering power it’s obvious to use synchrotron radiation sources with high brilliance. We investigate effect of proton concentration (pH) and temperature changes on the structure

and packing of model lipid matrix of stratum corneum. Measurements were conducted on DICSY beamline of Siberia-2 storage ring at NRC “Kurchatov Institute”. It is shown that main phase transition temperature decreases with increasing pH value. Lamellar two-phase structure translates into one-phase system. Lamellar repeat distance depends on temperature and pH. REFERENCES M. A. Kiselev, N. Y. Ryabova, A. M. Balagurov, S. Dante, T. Hauss, J. Zbytovska, S. Wartewig, and R. H. H. Neubert. New insights into the structure and hydration of a stratum corneum lipid model membrane by neutron diffraction. European biophysics journal: EBJ, 34(8):1030–40, 2005. M. A. Kiselev. Conformation of ceramide 6 molecules and chain-flip transitions in the lipid matrix of the outermost layer of mammalian skin, the stratum corneum. Crystallography Reports, 52(3):525–528, 2007. A. Schr¨oter, D. Kessner, M. Kiselev, T. Hauss, S. Dante, and R. H. H. Neubert. Basic nanostructure of stratum corneum lipid matrices based on ceramides [EOS] and [AP]: a neutron diffraction study. Biophysical journal, 97(4):1104–14, 2009

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Hard X-ray Nanoprobe at Beamline P06 at PETRA III.R.Hoppe1, A. Goldschmidt1, F. Seiboth1, P. Boye1,

J.M. Feldkamp1, J. Patommel1,D. Samberg1, A. Schropp1, S. Ritter1, V. Meier1, S. Hönig1,

C. Baumbach1, A. Schwab1,S. Stephan1, G. Falkenberg2, G. Wellenreuther2, N. Reimers2,P. Bhargava2, T. Claußen2, J. Reinhardt2 and C.G. Schroer1,

1 Institute of Structural Physics, TU Dresden, D-01062 Dresden, Germany 2 HASYLAB at DESY, Notkestraße 85, D-22607 Hamburg, Germany

At present, the storage ring PETRA III. at DESY in Hamburg is the most brilliant synchrotron radiation source. Hard x-ray scanning microscopy exploits the high brilliance particularly well and in 2010 the hard x-ray scanning microscope of the nanoprobe endstation of the beamline P06 at PETRA III. became operational [1]. Since then, experiments of many kinds were successfully performed [2, 3].

The nanoprobe instrument is located at 98.2 m from the source and is based on nanofocusing refractive x-ray lenses. It is designed to generate nanobeams with a lateral size of 50 nm and below and supports transmission, fluorescence, and diffraction contrast. Thanks to a rotation stage, even tomographic experiments with minimal eccentricity and wobble are accomplishable.

The scanner and detector units are mounted on a granite block directly deposited the concrete base unit and are designed for high stiffness but are also sufficiently versatile to allow for a wide range of experiments. Samples can be mounted on a stage with nine degrees of freedom including a high- precision and high-accuracy piezo-driven flexure stage on top of the rotation stage. The detector table allows to position several detectors (e.g. pixel detector, MAR camera, light microscope, PCO camera) from the wide- to the small-angle-scattering regime.

The detectors can also be positioned off-axis in the horizontal plane for Bragg-angle analysis. A fluorescence detector is positioned beside the scanner table facing the sample under 90 degrees.

REFERENCES

[1] Christian G. Schroer, Pit Boye, Jan M. Feldkamp, Jens Patommel, Dirk Samberg, Andreas Schropp, Andreas Schwab, Sandra Stephan, Gerald Falkenberg, Gerd Wellenreuther, and Nadja Reimers. Hard x-ray nanoprobe at beamline p06 at petra iii. Nuclear Instruments & Methods In Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 616(2-3), May 2010.

[2] A. Schropp, P. Boye, A. Goldschmidt, S. Hoenig, R. Hoppe, J. Patommel, C. Rakete, D. Sam- berg, S. Stephan, S. Schoeder, M. Burghammer, and C. G. Schroer. Non-destructive and quantitative imaging of a nano-structured microchip by ptychographic hard x-ray scanning microscopy. Journal of Microscopy, 241(1):9–12, January 2011.

[3] A. Schropp, R. Hoppe, J. Patommel, D. Samberg, F. Seiboth, S. Stephan, G. Wellenreuther, G. Falkenberg, and C. G. Schroer. Hard x-ray scanning microscopy with coherent radiation: Beyond the resolution of conventional x-ray microscopes. Applied Physics Letters, 100 (25), 2012.

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Fabrication and quality controlof the X-ray diffraction gratings at ANKA

D. Karpov1, V. Weinhardt1,2, D. Kunka3, F. Chen1, T. Baumbach1

1Affiliation one, 2Affiliation two, … [email protected]

INTRODUCTION In the past years x-ray imaging technique at the microscale has shown great potential in the material research. Due to the high penetration depth of the x-rays it is a non-destructive approach for studying of the volumetric samples. X-ray absorption contrast is limited to the samples which absorb minimum 20% of x-rays. Phase contrast imaging has a high sensitivity to small differences in electron density of the materials and unlike the absorption contrast it has a better contrast at higher photon energies. The quality of the phase contrast images obtained with Talbot interferometer depends on the quality of the X-ray diffraction gratings. At KIT in collaboration between Institute of Photon Science and Synchrotron Radiation (IPS), ANKA synchrotron and Institute for Microstructure Technology (IMT) we have established process of fabrication and quality control of the gratings. In this work we introduce new approach for the gratings quality evaluation.

FABRICATION The fabrication of the gratings is done at LIGA beamline of ANKA synchrotron. In the first step of LIGA fabrication process a photoresistive, but sensitive to X-rays, polymer is attached to a substrate. In the next step it is exposed to the beam of high energy synchrotron radiation through a specially designed mask of a strong X-ray absorbing material. After the exposure residual photoresist is chemically removed. Resulting structure is later filled with a desired metal by the process of electrodeposition [2]. TALBOT GRATING INTERFEROMETRY X-ray Talbot grating interferometry is an imaging method based on Talbot self-imaging effect. The method provides 3 contrast modes (absorption, phase and dark-field contrast) simultaneously. Talbot interferometry employs two diffraction gratings: phase grating (G1) and absorption grating (G2). Absorption grating is moved in the direction xg and the intensity distribution in each pixel of the detector is recorded at each step. The variation of the intensity can then be expressed as truncated

Figure 1. Principle scheme of Talbot grating interferometer

45


Fourier series [1]:

where i, j are the pixel coordinates, p2 is a period of absorption grating G2. Absorption contrast can be calculated as

, where indices r and s stand for the reference scan and the scan with a sample, respectively. To obtain the differential phase contrast following expression can be used:

, and for the dark-field contrast . It is possible to obtain

the visibility map of the grating while performing the scan without a sample as

. QUALITY CONTROL For the quality assessment of the fabricated gratings Talbot grating interferometry has been employed at the TopoTomo beamline of ANKA synchrotron. It was shown that visibility map of the grating and its visual inspection is not sufficient to conclude on the grating's quality. It was proposed to use test sample with known geometry for which expected phase contrast can be easily calculated (e.g. PMMA cuboid) for a qualitative visual inspection of the resulting phase contrast image along with visibility map. Moreover, to make the process quantitative it was decided to use three regions-of-interest (ROI). Signal-to-Noise Ratio (SNR) and

Contrast-to-Noise ratio (CNR) were calculated on the ROIs as following:

where is mean signal, σ is standard deviation of the signal, and indices s and b stand for sample and background, respectively. Table I. Results for 879p-0166_2_WP30 grating Grating SNRref SNR1 SNR2 CNR VisibilityNr1 6,05 21,9 0,16 6,7 18,75 Nr2 2 2,5 0,6 2,12 16,5 Nr3 78,9 69,3 73,7 1,84 15,6 By that it is possible to perform more accurate comparison measurements of the gratings with different design. CONCLUSION The new approach in the X-ray diffraction gratings quality assessment based on qualitative and quantitative inspection of the phase contrast image of the test sample has been described. The approach can provide more information required for the evaluation of the gratings fabrication and help to select the most suitable grating for the experiments which will result in better data quality. REFERENCES 1. Altapova et al. Opt. Express, 20(6):6496-6508, Mar 2012 2. Reznikova et al. Microsystem Technologies, 14:1683-1688, Oct 2008

Figure 2. Visibility map (left) and phase contrast of the test sample (right) for the 879p-0166_2_WP30 absorption grating

46


Study of Silicon-on-Sapphire structural quality by X-raydiffractometry, reflectivity and TEM methods

Blagov A.E.1, Vasiliev A.L.1, Kondratev O.A.1, Pisarevskiy Yu.V.1,Prosekov P.A.1, Seregin A.Yu.1

1A.V. Shubnikov Institute of Crystallography Russian Academy of Sciences, Leninskij prospect 59, Moscow, Russia

[email protected] The structures of the Silicon on sapphire (SOS-structure) are usually used in microelectronics, including the temperature sensors, high-performance radio-frequency (RF) applications and radiation-resistant integrated circuits and devices (UltraCMOS, RFICs, digital step attenuators etc). In the manufacture of these structures, using r-type sapphire substrates and silicon layer orientation [100], the application of epitaxial growth involving a silicon purification process raises a number of technical problems to fabricate a high-quality structures that may even lead to the destruction of the substrate. Those problems normally caused by crystal defects both in the epitaxial Si-layer and interfacial structure: twinning, misorientation, dislocations,

inhomogenity and lattice strain, etc. The purpose of the present study is to develop a comprehensive technique that allows us to observe the SOS-structure quality at every phase of production. Two SOS-structures, 150 mm diameter, thicknesses of Si-layer 0.3 and 0.1 μm, were studied by X-ray methods and electron microscopy. Samples were observed by transmission electron microscopy (TEM). The twins, domains with different orientations and other defects were found in both samples. Samples were investigated using high-resolution X-ray diffraction and X-ray reflectometry. In the high-resolution diffraction pattern for both samples series of rocking curves for substrate

Fig. I. TEM images: 1) – 0.1 μm sample 2) – 0.3 μm sample (arrows indicate areas of twinning).

1) 2)

47


and for silicon layer at different points were measured, and also measured the degree of disorientation of the substrate and silicon layer. For 0.3 micron structure was performed search of domains with an orientation other than [100] founded by microscopy. According to the results of

X-ray reflectometry the thickness of the silicon layer, the thickness of the transition layer was determined, and the density profile was built. The work was supported by RF Ministry of Education and Science (agreement 8574).

48


Monte-Carlo simulations of thermal neutron filter and neutronguide system for REVERANS reflectometer

P. Konik1, E. Moskvin1,2

1Petersburg Nuclear Physics Institute, 2Saint Petersburg State University

[email protected]

INTRODUCTION Monte Carlo technique is very useful for numerically analyzing all the components of neutron instruments before installing and allows optimal involving a large number of variables. Random numbers are used to select values for each variable and the resulting values are averaged. In order to check new concepts in polarized neutron instrumentation or to find the best ways of upgrading existing devices, it is nowadays inevitable to perform thorough Monte Carlo (MC) simulations. Analytic calculations are still another important method to check new ideas and even simulations in simple cases. However, MC methods can accurately handle very complex geometries, and multi-dimensional parameter spaces. Thus new ideas in neutron techniques need initially to be materialized in the MC simulation software. Virtual instruments based on Monte-Carlo techniques are now integral part of novel instrumentation development and the existing codes (McSTAS and Vitess) are extensively used to define and optimize novel instrumental concepts.

INSTRUMENT REVERANS is a polarized neutron reflectometer with the vertical scattering plane. The instrument is the only of such type in Russia. It allows to investigate structure of both free surface of liquids and interface. Physical, chemical and biological processes occurring on a free surface and on boundaries between different types of liquid systems and gas or solid can be researched. Such systems are organic and inorganic liquids, solutions, suspensions and colloid solutions of nanoparticles, liquid crystals, etc.

THERMAL NEUTRON FILTER Today REVERANS instrument is situated on the reactor WWR-M and is being moved from beam 12 to beam 3, which has much higher intensity. This beam gives a straight view to the active zone of the reactor and thus provides a lot of hot neutrons, that have to be filtered, because reflectometer is working with 6 Å neutrons. The main part of this thermal neutron filter is a multilayer mirror (m = 2.25). A specific V-like shape collimators installed before and after the mirror. These collimators are inclined by a critical angle to the mirror. So, cold neutrons are reflected by mirror, while hotter than 6 Å neutrons ignore mirror and are absorbed by iron surroundings of the device. The V-shape of collimators in vertical direction is needed to achieve the required vertical divergence. Using Monte-Carlo technique we defined optimal position and geometry, size and cover type of filter, geometrical properties of collimators.

NEUTRON GUIDE SYSTEM In not such distant future REVERANS will be moved to the neutron guide hall of the new high-flux reactor PIK. It is essential to construct a system of neutron guides filtering hot neutrons, giving as high vertical divergence as 7o, allowing effective monochromatization and polarizing of whole beam. Different types of guides (either straight, elliptic or parabolic) and their combinations are inspected and a proposal for a complex solution has to be formulated. ACKNOWLEDGMENT Authors wish to thank V. Zabenkin for useful discussions on a subjec

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Influence of radiation dose on the structureof cytochrome c nitritereductase

Lazarenko Vladimir1, Polyakov Konstantin2

1 NRC “Kurchatov Institute”, 2 Engelhardt Institute of Molecular Biology [email protected]

STATEMENT OF PURPOSE The main purpose of this research was to show the dynamics of the enzymatic activity of the protein expense of increasing the dose absorbed during the collection of diffraction data. INTRODUCTION Identify the principles of functioning of enzymes based on the knowledge of their spatial (tertiary and quaternary) structure is one of the main tasks of protein crystallography. Currently the most accurate model of the spatial structure provides a method of X-ray analysis, based on the analysis of X-ray diffraction from crystals of the studied object. However, X-ray analysis can only give a static picture, but when we work with proteins, we often want to see a dynamics. The object of study of this work is octohaem cytochrome c nitrite TvPaR, derived from the bacterium Thioalcalivibrio paradoxus [1]. TvPaR monomer comprises 553 amino acid residues and has a molecular weight of 64 kDa. Cytochromes catalyze nitrite reduction reaction of nitrite and ammonia to hydroxylamine and sulphite to sulphide. These reactions need additional electrons, which brings by another protein. APPROACH During data collection, analysis of X-ray crystal protein absorbs some radiation dose [2]. This is because all the photons of ionizing radiation, such as interacting with a crystal, only 8% are diffracted, and the rest goes to the photoelectric effect and the Compton effect [3]. Knocked out by photoelectric effect and Compton effect, electrons continue to interact with the atoms of the crystal, and will gradually reduce the protein molecules [4]. These electrons may be used for the enzyme catalytic reaction. Then more we have irradiated

the crystal, then more electrons will go into the active site and therefore will advance the further reaction. Due to the collecting of several data sets, we can get the required dose and as a result several static pictures which will see the gradual progress of the reaction. RESULTS AND DISCUSSION Were recorded in succession 5 complete sets of diffraction data with an increasing dose of ionizing radiation. Under the action of ionizing radiation, the recovery of the protein causes the enzyme nitrite reduction reaction.

Figure 1. The active site of TvPaR after dose of

0,4 MGy (set №1). On the Figure 1 we can see the active site of TvPaR after dose of 0,4 MGy. Catalytic residues of histidine, arginine and tyrosine, haem and nitrite were selected. Green denotes the electron density 2Fobs — Fcalc with depth in one sigma. Nitrite have a fully occupation.

50


Figure 2. The active site of TvPaR after dose of 2 MGy (set №5).

Not the same picture we can see on the Figure 2, after bigger dose. One oxigen was removed (oxigen 2, the other one will be the oxigen 1). After dose of 2 MGy the NO molecule and water, both with half occupation, are sitting in the active site. In this way we were able to see the initial stages of the recovery of nitrite to ammonia occurring under the influence of ionizing radiation. Firstly the oxigen 2 are splitted off, then the remaining molecule NO rotated so that the straight line passing through one oxygen and nitrogen becomes perpendicular to the heme (it is short-lived state, it can’t be detected by X-ray analysis) then oxygen 1 is turned on and place of oxygen 2. This explains the gradual disappearance of oxygen 1, while oxygen 2 are cutting off much slower. After a dose of 2 MGy oxygen 1 is no longer visible, because he turned around and took the free place of oxygen 2.

CONCLUSIONS 1) It is shown that under the action of ionizing radiation (with increasing dose) we were able to see the initial stage of the reduction of nitrite to ammonia. 2) It has been suggested as the first stage enzymatic reaction is the conversion of nitrite into NO molecule. REFERENCES [1] Tamara Tikhonova, Alexey Tikhonov, Anton Trofimov, Konstantin Polyakov, Konstantin Boyko, Eugene Cherkashin, Tatiana Rakitina, Dmitry Sorokin and Vladimir Popov, Comparative structural and functional analysis of two octaheme nitrite reductases from closely related Thioalkalivibrio species; FEBS J. 2012 Nov, 279, (21), 4052-61 [2] James M. Holton, A beginner’s guide to radiation damage, J. Synchrotron Rad. (2009). 16, 133–142 [3] Garman E. F., Radiation damage in macromolecular crystallography: what is it and why should we care? Acta Cryst. (2010). D66, 339–351 [4] Midori Sato, Naoki Shibata, Yokio Morimito, Yuki Takayama, X-ray induced reduction of the crystall of high-molecukar weight cytochrome c revealed by microspectroscopy, J. Synchrotron Rad. (2004). 11, 113–116

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Phase dynamics of Josephson junctionsS. Yu. Medvedeva1,2 and Yu. M. Shukrinov 1

1 BLTP, JINR, Dubna, Moscow Region, 141980, Russia 2Moscow Institute of Physics and Technology (State University),

Dolgoprudny, Moscow Region, 141700, Russia

In the capacitively coupled Josephson junctions model with diffusion current (CCJJ+DC model) [1, 2] the stacks with N intrinsic Josephson junctions is described by a system of dynamical equations

(1) for the gauge-invariant phase differences

between superconducting layers (S-layers). Here is the phase of the order parameter in S-

layer l, is the vector potential in the barrier. Time t is normalized to the inverse plasma frequency ( , Ic - critical current, C - capacitance), the voltage - to the value , the current - to the critical current Ic. For a given set of model parameters N, α, β, γ we simulate the CVC of the system. A change in these parameters changes the branch structure in the CVC essentially. Their influence on the CVC in the CCJJ and CCJJ+DC models was discussed in Refs.[2, 5, 6]. To calculate the voltages in each point of the CVC (for each value of I), we simulate the phase dynamics

(t) using the fourth-order Runge-Kutta method. Scheme of numerical procedure is presented in Fig. 1. The average voltage is given by

(2)

where Tmin and Tmax determine the interval for the averaging. After completing the voltage averaging for current I, the current I is increased

tN=Tf/Tp

Tp 3Tf

I

It + I3δ

δ

Time

Cur

rent

0

trt=t TP+Tf (It-I) / I0<t<tN*

It + Iδ

2TfTf

It + I2δ

trtIt

Tp - step in time;t - number of steps in time;tN - total number of

time steps;ti - initial number for

averaging procedure;Tf - size of time domain;Ti - initial time for

averaging procedure;It - initial current value

for time dependencerecording;

I - step in current;

Tp = 0.05;Ti = 50 - 500;Tf = 250 - 25000;

trt - recording time;

Parameters of simulation:

δ

FIG. 1 Scheme of numerical procedure for the phase dynamics in coupled Josephson junctions.

or decreased by a small amount δI to calculate the voltages at the next point of the CVC. We use the distribution of phases and their derivatives achieved in the previous point of the CVC as the initial distribution for the current point. Finally we obtain the total dc voltage V of the stack by

(3) Using Maxwell equation , where ε and ε0 are relative dielectric and electric constants, we express the charge density

in the S-layer l by the voltages Vl and Vl+1 in the neighbor insulating layers, where , and is Debye screening length. The charge dynamics in the S-layers determines the features of current voltage characteristics of the coupled Josephson junctions. Solution of the system of dynamical equations for phase differences gives us the voltages as functions of time Vl(t) in all junctions of the

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stack, and it allows us to investigate the time dependence of the charge in each S-layer. The recorded time is calculated by formula

. We use mostly Tf = 1000, δτ = 0.05 and δI = 0.0001 in our simulations.

[1] M. Machida, T. Koyama, A. Tanaka and M. Tachiki, Physica C 330, 85 (2000). [2] Yu. M. Shukrinov, F. Mahfouzi, P. Seidel. Physica C449, 62 (2006). [3] T. Koyama and M. Tachiki, Phys. Rev. B 54, 16183 (1996). [4] M. Machida, T. Koyama, and M. Tachiki, Phys. Rev. Lett. 83, 4618 (1999). [5] H. Matsumoto, S. Sakamoto, F. Wajima, T. Koyama, and M. Machida, Phys. Rev. B 60, 3666 (1999). [6] Yu. M. Shukrinov and F. Mahfouzi, Physica C 434, 6 (2006).

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Three-dimensional artificial spin ice in nanostructured Co on aninverse opal-like lattice

A.A. Mistonov1, N.A. Grigoryeva1, H. Eckerlebe2,N.A. Sapoletova3, K.S. Napolskii3, A.A. Eliseev3, D. Menzel4,

S.V. Grigoriev1,5

1Faculty of Physics, Saint-Petersburg State University, Saint Petersburg, 198504, Russia; 2GKSS Forschungszentrum, Geesthacht, 21502, Germany;

3Department of Materials Science, Moscow State University, Moscow, 119992, Russia; 4Institute of Condensed Matter Physics, Braunschweig, 308108, Germany;

5Petersburg Nuclear Physics Institute, Gatchina, Saint Petersburg, 188300, Russia [email protected]

We study magnetic properties of the three-dimensional ferromagnetic cobalt net ordered in the face centered cubic (fcc) structure –inverse opal-like structure (IOLS). The Co IOLS was prepared using a templating technique in three steps. First, polystyrene spheres with diameter of 540 nm form on the conductive substrate a colloidal crystal film (template) with fcc structure with the area of 1 cm2 and the thickness of 14 μm. Then, electrochemical crystallization of cobalt in the voids between the spheres was carried out. Finally, microspheres were dissolved in toluene. [1,2].

The basic element of this structure is a complex of quasitetrahedron, quasicube and another quasiterahedron connected along the spatial diagonal of the cube (<111>-type). The idealized element is presented in Fig. 1a. In reality the faces of these tetrahedra and cube are concave, since they were formed by the surface of the spherical particles.

The SANS experiments were performed at the SANS-2 setup in Geesthacht (Germany). A neutron beam with a wavelength λ = 1.2 nm, and a divergence η = 1.5 mrad was used. The scattered neutrons were detected by a PS detector set at a distance 21.5 meters from the sample. The Q-range was covered from 5 to 50 μm-1 with a step of

0.5 μm-1. Cobalt IOLS film was oriented perpendicularly to the incident beam. In this position the [111] axis of the fcc structure with the 3-fold symmetry was oriented parallel to the incident beam. The recorded neutron diffraction patterns consist of several clearly resolved sets of hexagonally arranged reflexes (Fig. 1b). The external magnetic field H up to 1.2 T was applied perpendicular to the incident beam and along the [ 121 ] axis of the IOLS.

Fig. 1. Projection of idealized basic element of IOLS on (111) plane with attached tetrahedra of four such neighbouring elements (a) and neutron diffraction patterns for Co IOLS in field H = 294 mT applied along [ 121 ] axis. The Miller indexes of the reflections corresponds to the fcc structure with the lattice constant of a0 = 0.76 ± 0.01 μm.

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SANS experiments have revealed a magnetization distribution coinciding with the spatial net of IOLS. We have constructed the model of this distribution, using the «ice-rule» concept [3,4].

Our model requires the magnetic flux conservation in tetrahedra and cubes of IOLS

to minimize the magnetic energy of the system. We compared the experimental SANS data with the scattering intensity predicted from the model and found a satisfactory agreement. Thus we show that the magnetic system of IOLS is determined

Fig. 2. Magnetization distribution in IOLS for the different state of the remagnetization process (a-f). The Ising-like magnetic moments directed along the <111> axes are shown by arrows in (220), (022) and (202) planes. Those of them, which lie in higher plane are lighter.

by the generalized «ice-rule» model and results in the macroscopically measured component of magnetization perpendicular to the applied magnetic field. The local distribution of the magnetization at the different stages of the remagnetization process is presented in Fig. 2. Each stage is characterized by the critical magnetic field Hci corresponding to the remagnetization of the different elements of the basic unit cell of the magnetic net of the IOLS.

ACKNOWLEDGMENT Work was supported by the DAAD program «Dmitry Mendeleev» 2012 and RFBR grant № ofi-m 12-02-12066/12.

REFERENCES [1] S.V. Grigoriev, K.S. Napolskii, N.A. Grigoryeva, A.V. Vasilieva, A. A. Mistonov,

D. Yu. Chernyshov, A. V. Petukhov, D. V. Belov, A. A. Eliseev, A. V. Lukashin, Yu. D. Tretyakov, A. S. Sinitskii, H. Eckerlebe, Phys.Rev. B, v. 79, 045123 (2009)

[2] N. A. Grigoryeva, A. A. Mistonov, K. S. Napolskii, N. A. Sapoletova, A. A. Eliseev, W. Bouwman, D. V. Byelov, A. V. Petukhov, D. Yu. Chernyshov, H. Eckerlebe, A. V. Vasilieva, and S. V. Grigoriev, Phys.Rev. B, v. 84, 064405 (2011)

[3] M. J. Harris, S. T. Bramwell, D. F. McMorrow, T. Zeiske and K. W. Godfrey, Phys. Rev. Lett., v. 79, 2554 (1997).

[4] A.P. Ramirez, A. Hayashi, R.J. Cava, R Siddharthan, and B.S. Shastry, Nature, v. 399, 333 (1999)

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Applying the Synchrotron Radiation for the Studying Phase-formation during Combustion of

the Aluminum Nanopowder in AirAndrey V. Mostovshchikov, Alexander P. Ilyin, Nikolay

A. TimchenkoTomsk Polytechnic University

[email protected]

INTRODUCTION Scientific and practical interest in aluminum nanopowders is firstly due to the prospects of their use in rocket propellants, hydrogen power engineering, and powder metallurgy. Meanwhile, an example of specific application of Al nanopowders is obtaining aluminum nitride by combustion in air [1]. The modern electronics industry widely uses substrates of aluminum nitride because it has high thermal conductivity and is a dielectric, so that studying the mechanism of aluminum nitride formation and improving its production technology are urgent problems [2]. At atmospheric pressure, aluminum nitride does not form a liquid phase, and it grows only from a gas phase. In the classical view, this process requires low temperature gradients and small vapor supersaturation and should occur at low rates for a relatively long time [3]. Under high temperature gradients or large supersaturation, i.e., under nonequilibrium conditions, aluminum nitride whiskers are formed [2]. At the same time, combustion of aluminum nanopowder under the influence of a constant magnetic field produces aluminum nitride microcrystals of hexagonal shape [2]. In the combustion of aluminum powder with free access of air, the main final product is aluminum nitride in the form of an independent crystalline phase. In this phase, the weight content of aluminum nitride is 30–90% [1]. The combustion of an Al nanopowder sample in the form of a freely poured cone or a compacted cylinder occurs in two stages: the first is characterized by low temperatures due to burnout of the hydrogen absorbed by aluminum

nanoparticles, and the second corresponds to aluminum oxidation with oxygen and nitrogen in the mode of thermal explosion. The thermal explosion is characterized by a sharp increase in the sample temperature from 800 to 2400◦C for 5–10 s, and is not accompanied by expansion of the burning sample (combustion products) and formation of a high-velocity gas stream. The second stage of combustion is the formation of aluminum nitride in the form of whisker crystals [2]. Despite the studies performed, the stages of phase formation in the combustion of Al nanopowders have not been studied in sufficient detail. The purpose of this study is to establish the sequence of formation of product crystalline phases during combustion of pressed aluminum nanopowder in air using synchrotron radiation.

EXPERIMENTAL PROCEDURE The samples were prepared by compacting the aluminum nanopowder in a steel press mold under a pressure of 7.5 MPa. The diameter of the obtained cylinders was 10 mm, the height was 7 mm, and the weight 0.4 g. The experiments were performed in the Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, using the Station “Precision Diffractometry II” (SR channel No. 6 of the VEPP-3 electron storage ring), and the wavelength of the incident radiation was 1.0731 Å. Detailed information about the equipment and parameters and photographs of the diffractometer with the OD-3M one-coordinate detector are available on the Internet [4].

RESULTS AND DISCUSSION

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We placed the sample on the work table of the diffractometer, focused the synchrotron radiation on the sample surface, initiated combustion, and recorded diffractograms (fig. 1) of the surface of the burning compacted aluminum nanopowder [5]. According to the results obtained, aluminum initially reacts with air oxygen, which heats the sample. In the range of 8–15 s from the beginning of combustion, the combustion products are in the gas phase and are not detected using synchrotron radiation. Formation of the crystalline phases of the products on the sample surface starts at the 15th second after the initiation of combustion. Based on the ratio of the reflection intensities, the main products of combustion of aluminum on the sample surface and in the volume of the sample are Al2O3 and AlN, respectively. According to the diffractograms of the burning sample surface obtained using the synchrotron radiation (fig. 1), the formation of the crystalline phases goes through the following stages. 1. After initiation of the combustion and heating of the aluminum nanopowder, the intensity of the diffraction maxima of metallic aluminum decreased: the diffractogram shows the first

stage of the two-stage combustion process, which involved melting of, aluminum inside the powder nanoparticles at a temperature 660◦ C. 2. During the reaction of nitride formation, which corresponds to the second stage of combustion, the diffractogram did not show reflections of metallic aluminum and the temperature of the sample abruptly increased. 3. About 15 s after the initiation of combustion, the crystalline phases of aluminum oxide and silicon oxynitride (Al5O6N) began forming. 4. The formation of the crystalline phase of aluminum nitride and metallic aluminum was observed after about 22 s from the start of combustion. CONCLUSIONS 1. In the products of complete combustion of pressed samples of aluminum nanopowder, the main phase (100% reflex) is aluminum nitride, and the content of the remaining crystalline phases does not exceed 27% (fig. 2). 2. In the combustion of aluminum nanopowder, aluminum γ-oxide is the first to form. 3. The formation of aluminum probably occurs by successive displacement of oxygen by nitrogen from the aluminum oxide.

Fig. 1. Diffractograms of the burning aluminum

nanopowder sample (surface)

Fig. 2. Diffractogram of the final products (bulk)

REFERENCES 1. A. P. Il’in and L. T. Proskurovskaya, “Two-Stage Combustion of an Ultradispersed Aluminum Powder in Air”, Combust., Expl., Shock Waves, 26 (2), 190–192 (1990). 2. A. P. Il’in, A. V. Mostovshchikov, and L. O. Root, “Growth of Aluminum Nitride Single Crystals under Thermal Explosion Conditions”,

Technical Physics Letters, 2011, Vol. 37, No. 10, pp. 965–966. 3. A. Laudise and R. L. Parker, The Growth of Single Crystals, Vol. 25: Solid State Physics, Academic Press, NewYork–London, 1970). 4. Siberian Synchrotron and Terahertz Radiation Center, Budker Inst. of Nuclear Physics,

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Siberian Branch, Russian Academy of Sciences, Novosibirsk; http://ssrc.inp.nsk.su/CKP/. 5. A. P. Il’in, A. V. Mostovshchikov, N. A. Timchenko, “Phase Formation Sequence in

Combustion of Pressed Aluminum Nanopowder in Air Studied by Synchrotron Radiation”, Combust., Expl., Shock Waves, 49 (3), 320–324 (2013).

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Structure of supported catalysts: x-ray synchrotron diagnosticsin situ

Murzin V.Y.1, 2, Zubavichus Y.V.1, Veligzhanin A.A.1, Bruk L.G.3,Bukhtiyarov V.I.4

1 National Research Center «Kurchatov Institute» 2 Topchiev Institute of Petrochemical Synthesis RAS

3 Lomonosov Moscow State University of Fine Chemical Technologies 4 Boreskov Institute of Catalysis SB RAS

[email protected] INRODUCTION Catalysts play important role in many important industrial chemical processes. In order to improve their properties and get more active, selective, stable or environmentally friendly catalysts we should know how they work at different structure levels. Moreover, it is important to analyze the structure of catalysts during the process or in situ.

X-ray methods are the main tools for such structure analysis. But often there is a case that catalysts (especially supported) contain only a few percent of active component. Therefore, to analyze the structure of such components highly sensitive methods are required. The best choice is to use synchrotron radiation sources which

Fig.1. Photo of the Structural Materials Science end-station at the NRC “Kurchatov Institute”. SR – synchrotron radiation. I0 –current in the first ionization chamber (before the sample), It –current in the second ionization chamber (after the sample).

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have intensities orders of magnitude higher than conventional x-ray tubes. In this work two catalytic systems supported on gamma-alumina (containing 0.8 wt.% Pt and 1.5 wt.% Pd / 3.5 wt.% Cu correspondingly) were

analyzed in situ using XRD, XANES and EXAFS methods at the Structural Materials Science end-station of the National Research Center “Kurchatov Institute” [1] (Fig.1).

RESULTS In situ XANES studies of the Pt catalyst for methane oxidation have confirmed the concentration hysteresis in the effective Pt oxidation state (Fig. 2) [2]. Evidently, there are two forms of platinum stable within specific concentration ranges of oxygen in the initial reaction media (IRM). These stability ranges depend on the direction of the oxygen concentration variation. The Pt switches from fully metallic to partly oxidized state at 2.0-3.0

vol.% when increasing the oxygen concentration and at 1.5-1.0 vol.% when decreasing it. The transition of supported platinum to the active state is probably caused by partial reduction of PtO2 species under the fuel-rich conditions. In situ XRD, XANES and EXAFS studies of the PdCu catalyst for low-temperature CO oxidation have shown that the initial catalyst contain palladium in the complex form [PdHal4]

2- (Hal = Cl, Br) on the surface of gamma-Al2O3 and copper in the crystalline form Cu2(OH)3Hal. There was no evidence of Cu and Pd contacts in

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Fig.2. In situ XANES measurements of the Pt catalyst during methane oxidation. Increase of the O2 concentration in the IRM: a) 0.5% b) 1.0% c) 1.5% d) 2.0% e) 2.5% f) 3.0% g) 4.0% and subsequent decrease of the O2 concentration in the IRM: h) 3.0% i) 2.5% j) 2.0% k) 1.5% l) 1.0% m) 0.5%. Conditions: 400oC, 1% vol.% CH4. Inset shows enlarged view of XANES spectra for the catalyst d) (solid line) and j) (dashed line) compared to references Pt foil (filled circles) and K2Pt(NO2)4 (open circles).

60


the catalyst. During the reaction Pd reduces to metallic form and copper reduces to Cu+. In the oxygen environment the catalyst regenerates back to its initial form. ACKNOWLEDGMENTS The work was partially supported by Russian Foundation for Basic Research (projects № 11-03-00298, 11-03-00820, 13-03-01003)

REFERENCES [1] A.A. Chernyshov, A.A. Veligzhanin, Y.V. Zubavichus, Nucl. Instr. Meth. Phys. Res. A 603 (2009) 95. [2] I.Yu. Pakharukov, I.E. Bekk, M.M. Matrosova, V.I. Bukhtiyarov, V.N. Parmon Dokl. Phys. Chem. V439 (2011) 1, 131-134

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Pressure-induced phase transitions in the langasite structurecompound Ba3TaFe3Si2O14

P. G. Naumov1,2, I. S. Lyubutin1, V. Ksenofontov2, S. Medvedyev3

and C. Felser3

1Shubnikov Institute of Crystallography, Russian Academy of Sciences, 119333, Moscow, Russia 2Max-Planck Institut for Chemie, Mainz, 55020 Germany

3Anorganische Chemie, Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany.

[email protected]

INTRODUCTION Recently, a great interest was attracted to the langasite family compounds containing 3d ions as potential new type of multiferroics. The langasite La3Ga5SiO14 crystal famous by its unique piezoelectric properties exceeding quartz gave the name to the whole family [1]. Among such compounds, the materials with paramagnetic iron, cobalt and manganese ions A3BM3X2O14 (A = Ba, Sr, Ca, Pb; B = Sb, Nb, Ta, Te; M = Fe, Co, Mn, X = Si, Ge, P, V, As) were synthesized [2]. The magnetic [2-5] and Mössbauer spectroscopy [6,7] measurements revealed an antiferromagnetic ordering in a number of these compounds at temperatures between 7 and 38 K. Supposed coexistence of electric and magnetic order parameters in such materials would provide a creation of a new class of multiferroics [8,9]. The possible structural phase transitions initiated by temperature and pressure in the langasite-family compounds were discussed in [10]. The change of the trigonal symmetry (space group P321) to monoclinic (space group A2-C2) was found in La3SbZn3Ge2O14 with lowering temperature and in La3Nb0.5Ga5.5O14 and La3Ta0.5Ga5.5O14 under high pressure. We present the high-pressure X-ray diffraction and Mössbauer spectroscopy studies of structural properties of the Ba3TaFe3Si2O14

compound. RESULTS AND DISCUSSION

X-ray diffraction data High-pressure X-ray powder diffraction studies of Ba3Ta57Fe3Si2O14 were performed at the beamline BL01C of National Synchrotron Radiation Research Center (NSRRC, Taiwan) at photon energy 22 keV (λ=0.564 Å). The powder sample was loaded in in diamond anvil (500 µ culet size) cell (DAC) with silicon oil as pressure transmitting medium. A standard ruby fluorescence technique was used to measure pressure. Pressure evolution of X-ray diffraction patterns of Ba3Ta57Fe3Si2O14 is shown in Fig. 1. Diffraction patterns at low pressures can be unambiguously assigned to known trigonal langasite crystal structure with lattice parameters a = 8.54 Å, c = 5.24 Å at 0.5 GPa. This structure remains stable up to P = 18.4 GPa at which splitting of diffraction lines (e. g. at 2 4.3°) indicates a phase transition to high-pressure phase tentatively indexed with monoclinic unit cell. No further phase transitions are observed up to the highest experimental pressure 37 GPa.

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Fig. 1. X-ray patterns of Ba3Ta57Fe3Si2O14 recorded at ambient pressure and at P = 18 and 37GPa. Mössbauer spectroscopy data At room temperature and ambient pressure the Mössbauer spectra of Ba3Ta57Fe3Si2O14 are split by the electric quadrupole interaction into a doublet with narrow symmetrical lines. The quadrupole splitting parameter is ΔE = 1.255 ± 0.005 mm/s, which is very high for Fe3+ ions. This indicates that the oxygen tetrahedrons with iron ions are essentially distorted. The isomer shifts value is = 0.23 ± 0.1 mm/s (relative to metallic α-Fe) which supports the ferric iron state. ΔE value shows non-monotonous behaviour with pressure increase. At pressures below 5 GPa value of ΔE remains almost unchanged followed by rapid value decrease to about 0.85 mm/s at further pressure increase up to 7 GPa (Fig. 2). The origin of this decrease is apparently the pressure induced symmetrisation of local crystal field of Fe+3 ions. At further pressure increase at P < 18 GPa, the ΔE value remains almost stable at the level of 0.85 ± 0.03 mm/s. At pressure above 20 GPa ΔE suddenly increases with subsequent gradual increase reaching the value of about 1.3 mm/s at highest experimental pressure P = 30 GPa. The high pressure behaviour indicates of the quadrupole splitting parameter indicates structural phase transition in Ba3Ta57Fe3Si2O14 occurring at pressure above 18 GPa in

accordance with results of high-pressure structural studies.

Fig. 2. Pressure dependences of the quadrupole splitting parameter in Ba3Ta57Fe3Si2O14. Solid lines are guide for eyes. CONCLUSION The high-pressure X-ray diffraction and Mössbauer spectroscopy measurements were performed in the iron containing langasire family compound Ba3Ta57Fe3Si2O14 in diamond anvil cells. The structural transition were found by all these methods at pressure of about 18–30 GPa. ACKNOWLEDGMENT We deeply thank Dr. B.V. Mill for his help in the synthesis the Ba3TaFe3Si2O14 sample with 57Fe isotope. This work is supported by the Russian Foundation for Basic Research (grants 13-02-12419-ofi-m and 11-02-00636-а) and by RAS programs “Strongly correlated electron systems”. REFERENCES [1] B. V. Mill, E. L. Belokoneva, and T. Fukuda, Russian J. Inorg. Chem. 43, 1168 (1998). [2] B. A. Maksimov, V. N. Molchanov, B. V. Mill, E. L. Belokoneva, M. K. Rabadanov, A. A. Pugacheva, Y. V. Pisarevsky, V. I. Simonov, Crystallography Reports 50, 751 (2005). [3] K. Marty, V. Simonet, E. Ressouche, R. Ballou, P. Lejay, P. Bordet, Phys. Rev. Lett. 101, 247201 (2008).

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[4] V. Yu. Ivanov, A. A. Mukhin, A. S. Prokhorov, B. V. Mill, Solid State Phenomena 152-153, 299 (2009). [5] K. Marty, V. Simonet, P. Bordet, R. Ballou, P. Lejay, O. Isnard, E. Ressouche, F. Bourdarot, P. Bonville, J. Magn. Magn. Mater. 321, 1778 (2009). [6] I.S. Lyubutin, P.G. Naumov, B.V. Mill’, Euro Phys. Lett. 90, 67005(1–6) (2010).

[7] I.S. Lyubutin, P.G. Naumov, B.V. Mill’ , K.V. Frolov, and E.I. Demikhov, Phys. Rev. B 84 (2011) 214425 (1–7). [8] S.A. Pikin and I.S. Lyubutin, Phys. Rev. B, 86 #6 (2012) 064414. [9] S.A. Pikin and I.S. Lyubutin, JETP Lett. 96, #4 (2012) 240–244. [10] B. V. Mill, B. A. Maksimov, Yu. V. Pisarevsky, N. P. Daniliva, A. Pavlovska, S. Werner, and J. Schneider, Crystallography Reports 49, 60 (2004)

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Grafted Polylactide particles and their Repulsive ForcesRobertus Wahyu N. Nugroho, Torbjörn Pettersson, Karin Odelius,

Anders Höglund, and Ann-Christine AlbertssonDepartment of Fibre and Polymer Technology, KTH Royal Institute of Technology,

SE-10044 Stockholm, Sweden [email protected]

ABSTRACT Agglomeration is a primary problem for small particles in the range of several tenths of nanometers to hundreds micrometers. This physical behavior reduces the particles numerous advantages for a wide range of applications. One way to prevent this problem is to graft hydrophilic polymer chains onto the surface of the particles, thus resulting in sterically stabile particles. There are numerous methods by which the surface modification can be attained, such as by a ‘grafting-from’ technique under UV-irradiation. In this work, polylactide (PLA) particles were surface grafted under UV-irradiation with the hydrophilic monomers: acrylic acid (AA), acrylamide (AAm), and maleic anhydride (MAH). The ‘grafting-from’ technique was initially developed and shown to be nondestructive for PLA particles with different geometries. The change in surface chemistry of the PLA particles, as confirmed by X-Ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infra-Red (FTIR), indicated the success of surface grafting technique. Force interaction between two grafted PLA substrates was measured by colloidal probe Atomic Force Microscope (AFM) in salt solutions with different concentrations to investigate repulsive forces due to steric stabilization. In order to evaluate force

interaction, AFM force profiles were compared to the Alexander de Gennes (AdG) model and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Repulsive forces were mainly detected in a long range interaction when hydrophilic polymers were covalently attached to the particles surface. On the contrary, attractive forces dominated the interaction when neat PLA particles approaching each other to agglomerate, even though short range repulsion was detected at small separation distance. The surface grafted particles can be used in biomedical field, e.g. drug delivery research to overcome particle aggregation. Keywords: Surface modification, AFM, hydrophilic polymers, steric stabilization, polylactide, acrylic acid, acrylamide, maleic anhydride. ACKNOWLEDGEMENTS The ERC Advanced Grant, PARADIGM (Grant agreement no: 246776) for financial support for this work. REFERENCES 1. Nugroho, R.W.N., Odelius, K., Höglund, A., Albertsson, A.-C., ACS Appl. Mater. Interfaces 2012, 4, 2978–2984. 2. Nugroho, R.W.N., Pettersson, T., Odelius, K., Höglund, A., Albertsson, A.-C., Langmuir 2013, 29, 8873–8881.

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The reaction of decomposition of MnB2H8

Pankin Ilya1, Guda Alexander 1, Filinchuk Yaroslav 2, Soldatov Alexander 1

1Nonoscale structure of matter, Southern Federal University, Sorge 5, Rostov-on-Don, Russia. 2 Institute of Condensed Matter and Nanosciences,

UniversitéCatholique de Louvain, Place L. Pasteur 1, B-1348, Louvain-la-Neuve, Belgium E-mail: [email protected] web: http://www.nano.sfedu.ru

STATEMENT OF PURPOSE The object of study is borohydride of manganese MnB2H8. This compound is a solid state hydrogen storage system. However the complete desorption of hydrogen destroys of initial material. Thus further use of this accumulator of hydrogen becomes not possible. The main purpose of this investigation is determination of possible reaction products decomposition process of initial material to study process of degradation. INTRODUCTION Due to the limited and non-renewable of conventional energy source humankind is interested in the search for alternative sources of energy e.g. hydrogen energetic. However the problem of storage of hydrogen fuel is not solved. The possible solutions to the problem — the use of solid-state hydrogen storage systems based on alanates and borohydrides of alkali and rare-earth metal. In our study we use borohydride of manganese MnB2H8. Due to its unique thermodynamic properties and possibility of in-sity measurement of Mn K-edge XANES spectra (in contrast to light elements such as Li or Mg) this compound has a great prospects.

APPROACH The conventional method which used for determination of structure of crystal and other solid-state matter is X-ray diffraction (XRD). But in our case initial material was degraded in the process of reaction of decomposition which was induced by heating the sample. XRD shows that with increasing temperature sample loses periodical crystal structure. To

determine the chemical composition and structure of reaction products we used XANES (X-ray absorption near edge structure) analysis. This method of spectroscopy is very sensitive both to the electronic state of absorbing atom and to its local environment. So it allows us investigate the local structure of nanoparticles, amorphous and bio-samples. t XANES experimental spectra indicate on phase transition which is observed by heating sample. Two different theoretical methods were used for modeling of XANES spectra. Both are implemented in the software package FDMnes. First is based on full multiple scattering theory and muffin-tin approximation. The basis approximation lies in the potential in which the potential is assumed to be spherically symmetric in the muffin tin region and constant in the intermediate region. However for unknown compound muffin-tin approximation failed to reproduce the XANES spectrum and time-consuming Finite Difference Methods (FDM) to was used instead which allows to avoid muffin-tin approximation. However in our both ways bring to similar result. RESULT AND DISCUSSION Firstly we have reproduced the spectra of initial compound to assess the acceptability of theoretical methods. Figure 1 shows experimental spectrum for initial compound MnB2H8 corrected on self-absorption. The curves under experimental spectrum represent theoretical simulations for different inequivalent positions of Mn. Therefore spectra calculated for different absorption atom were summed with weights corresponding concentration of non-

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equivalent manganese atoms in the unit cell Mn1 and Mn2.

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From stoichiometry of initial compound as a first model were calculated spectra for diboride of manganese MnB2 (Figure 2). Figure 2 shows experimental Mn K-edge XANES spectrum after sample was heated up to 140 degrees.

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As we see the theoretical spectra does not satisfactorily describes experimental curve — thus another manganese boride compounds should be taken into account. The result of modeling are shown in Figure 3. The spectra calculated for MnB, Mn2B and MnB4 in a good agreement with experimental data. Due this fact we can consider this compounds as a possible product the reaction of decomposition. However for more precise estimation we must use complementary methods of analysis. At present

time the EXAFS data analysis is in progress. In the future we plan to use the technique of molecular dynamic.

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CONCLUSIONS Mn K-egde XANES spectra were measured in situ during heating process of MnB2H8 in vacuum and hydrogen atmosphere. At 110 degrees diffraction patterns disappear and sample decomposition occurs. From theoretical analysis of XANES spectra we conclude that possible reaction products of decomposition process has local Mn structure similar to mixture of MnB, Mn2B and MnB4 while formation of MnB2 and Mn3B4 in the process of reaction are excluded. REFERENCES [1] Bugaev A.L., Guda A.A., Dmitriev V.P., Lomachenko K.A., Pankin I.A., Smolentsev N.Yu., Soldatov M.A.,Soldatov A.V. Operando dynamics of the nanoscale atomic and electronic structure of materials for hydrogen storage, Engineering Journal of Don, 4–1 (2012) [2] Filinchuk Y., Richter B., Jensen T.R., Dmitriev V., Chenryshov D., Hagemann H. Angew. Chem. Int. Ed. 2011. V. 50. No 47. P. 11162–166.

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Mössbauer study of the FeSeTe compound systemPerunov I.V. 1, Frolov K.V.1, Vasyukov D.M.1,Lyubutin I.S.1,

Korotkov N.Yu.1, Belikov V.V.2, Kasakov S.M.2, Antipov E.V.21Shubnikov Institute of Crystallography RAS, Moscow, Russia, 2 Lomonosov Moscow State University,

Moscow, Russia [email protected]

INTRODUCTION

The recent discovery of superconductivity in the iron-based pnictides and chalcogenides has generated considerable research interest and initiated a new discussion about possible magnetic mechanisms of the high temperature superconductivity1,3,4. The FeSeTe compounds are considered as a structural simplest compound system. Fe-based chalcogenides demonstrates high values of critical current and critical field Hc2. The remarkable fact is that FeSe compound undergoes superconducting transition at low temperatures while FeTe reveals antiferromagnetic ordering below 70 K. The investigations of structural, electron and spin states of Fe ions allow getting new important information about possible mechanisms of formation of the superconducting state.

STATEMENT OF PURPOSE

In our work we pursued two main purposes. First of all was to investigate structural, electron and spin states of Fe ions. Second goal was to studying of correlation between magnetic ordering of Fe ions and superconductivity.

APPROACH

We chose the absorption 57Fe Mossbauer spectroscopy as a method of investigation. The samples were synthesized by solid-state reaction process, phase composition were under control via x-ray methods2. As a result the majority of the samples were multiphased. We chose the purest samples for low temperature experiments.

RESULTS AND DISCUSSION

Our investigation of the samples of FeSeTe compound at 295-5 K temperatures yielded the next results. Mossbauer spectra at 295 K have paramagnetic shape, magnetic ordering is not observed. We reveal small magnetic ordering at the temperatures below critical one for the purest samples (FeSe0.5Te0.5, FeSe0.2Te0.8). The comparison of Mossbauer spectra of superconducting FeSeTe compound and non-superconducting Fe1+xTe showed that with increasing of portion of Te in FeSeTe system there’s no rise of magnetic ordering. This fact points out on probable crucial role of interplanar ions of Fe which may cause strong magnetic ordering.

ACKNOWLEDGMENTS

This present work was supported by Russian Fund of Fundamental Investigations (grants № 10-03-00681 and № 11-02-00636) and Project of Departure of Physical Sciences «Strongly correlated systems».

REFERENCES

1. Kamihara Y. et al. Iron-Based Layered Superconductor La[O1-xFx]FeAs (x=0.05-0.12) with Tc=26 K. J. Am. Chem. Soc. 130,3296-3297(2008).

2. Kasakov S.M. et al. A-site substitution in Fe1.1Te: synthesis, structure and properties. Chem.Met.Alloys //3,155-160 (2010).

3. Mizuguchi Y., Takano Y. J. Review of Fe Chalcogenides as the Simplest Fe-Based superconductor. J. Phys.Soc. Jpn. Vol. 79, 10.102001(2010).

4. Shermadini Z. et al. Coexistence of Magnetism and Superconductivity. In the Iron-Based Compound Cs0.8(FeSe0.98)2. Phys.Rev.Lett. 106,117602(2011).

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Study of nanostructural organization of animal hair biologicalfiber with X-ray diffraction methods using synchrotron radiation

A.Yu. Gruzinov1, A.A. Vasilyeva2 G.S. Peters1, V.V. Stepanova2

I.A. Staroselskiy1,3 A.V. Zabelin1,2, A.G. Malygin4 A.A. Vazina1,2

1RRC “Kurchatov Institute”, Moscow, Russia, 2Institute of Theoretical and Experimental Biophysics RAS, Puschino, Russia,

3Lomonosov Moscow State University, 4Bach Institute of Biochemistry RAS, Moscow, Russia

[email protected];

STATEMENT OF OBJECTIVE The science of tissue structural biology is just starting, and conceptual and instrumental approaches for studying the structural biology of tissue are only going to be developed. X-ray diffraction patterns of various native tissues are of fibrillar type and can be attributed only to a few archetypes of diffraction patterns. The characteristic features of small-angle X-ray patterns are determined by the structure of major fibrillar cytoskeletal proteins, such as keratin, actin, myosin, tubulin etc., and extracellular matrix of the fibrous protein collagen and proteoglycan structures. Our previous analysis of diffraction patterns of native epithelial tissues reveals their similarity to the diffraction patterns of mucus [1, 2, 3]. The similarity of diffraction patterns of epithelial tissue and mucus allows to combine them into a completely new archetype of small-angle X-ray patterns, characteristic feature of which is presence of multiple Bragg reflexes of the Debye type with a major period 4.5 nm. As a model hair tissue (keratinized epithelial tissue) was chosen because it has a rich fibrillar type diffraction pattern, which is characterized by translational symmetry in two directions — lateral and axial. METHODS AND OBJECTS OF STUDY X-ray diffraction experiments were performed on the small-angle diffraction station DICSI [4] stated on the storage ring "Siberia-2" (RRC "Kurchatov Institute", Moscow) at λ = 0.162 nm. Semiconductor CCD-matrix (MAR CCD), being cooled to -80 degrees, was used as a

detector. Typical exposure times were 1-5 minutes, beam current = 70–100 mA. Standard diffraction patterns of silver behenate powder and samples of moist collagen from rat tail tendon were taken to calibrate the scale of scattering angles. Collections of the animal hair used in the hair studies: Collection 1 — several hundred samples of different species of animals (mice, rats, dogs) from the animal house of the FIB Chelyabinsk-40. These animals varied in age, sex, feeding and housing conditions. Collection 2 — mice from the Bach Institute of Biochemistry RAS (Prof. A.G. Malygin), which consisted of about 300 individuals, the descendants of normal females and males with an inherited mutation producing a dwarf phenotype. The criteria for mutations were body weight, growth retardation, life expectancy and mortality rate [5]); Collection 3 — rats of two age groups and housed in two different animal houses with significantly different conditions. RESULTS AND DISCUSSION Diffraction patterns from tissues of animals of these different collections show the presence of cytoskeleton (keratin) fibrillar structures as well as extracellular matrix (proteoglycan). Comparative analysis of the diffraction patterns shows considerable variation in diffraction line parameters and diffuse small-angle scattering, the intensity and symmetry of which was changed from radial and ellipsoidal to hexagonal.

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A preliminary conclusion from the comparative analysis is that the diffraction patterns of the mutants are characterized by a multitude of reflections produced by keratin fibrils (fig. 1, b). The diffraction patterns of samples of normal mice are significantly different from those of mutants and are more similar to the patterns from collection 1 samples, which have much fewer reflexes, poor intensity and contrast (fig. 1, a). This phenomenon can be attributed to the flexibility of keratin fibrils, resulting in a change of the chain conformation. It can be noted that in the diffraction patterns of normal mice, as well as rats and mice from collections 1 and 3, Bragg reflections of Debye type with 4.5 nm period are registered, which can be attributed to the presence of proteoglycan fibrils (fig. 1, а). Fig. 1. Small-angle diffraction patterns of mice hair tissue — normal (a) and mutant (b).

Diffraction patterns of mutant mice (b) have a clear set of meridional reflections attributed to supercoiling α-helical bundles packed in keratin intermediate filaments, which is the most intense reflex with 6.7 nm period a seventh order of the major 47 nm period. Diffraction pattern of samples of normal mice from collection 2 (a), which differ significantly from those described above, are similar to the patterns of control samples from collection 1 The role of element composition in the nanostructural transformation of the extracellular matrix consisting of proteoglycan fibrils is currently being discussed. A mechanism of conformational lability of

proteoglycan structures in the modifying adaptation of biological tissues to endogenous and exogenous influences is proposed. Our nanostructural studies of hair and fur tissues of animals allow raising the fundamental question of biophysics about the interdependence of “structure and function”. Hair tissue of animals in poor physiological state give a clearer small-angle diffraction pattern than tissue of healthy animals living in good conditions, which have a bigger adaptation potential to endogenous and exogenous influences. The obtained results of nanostructural research of biological tissues using synchrotron radiation can be applied to identification of morphological markers suitable for monitoring of the physiological state of tissues. REFERENCES 1. Aksirov A.M., Vazina A.A. et al., Biological and medical application of SR from the storage rings of VEPP-3 and “Siberia-2”. The origin of specific changes of small-angle X-ray diffraction pattern of hair and their correlation with the elemental content, Nucl. Instr. Meth. in Phys. Res., 2001, vol. A470, p. 380-387. 2. Vazina A.A., Bras A.Yu. et al., Peculiarities of human hair structural dynamics, Nucl. Instr. Meth. in Phys. Res., 2005, vol. A543, p. 153-157. 3. Vazina A.A., Budantsev, A.Yu., Bras et al., X-ray diffraction and spectral studies of biological native and modified tissues, Nucl. Instr. Meth. in Phys. Res., 2005, vol. A543, p. 297-301. 4. Ariskin N.I., Gerasimov V.S., Korneev V.N., Stankevich V.G., Vazina A.A. et al., System of primary collimators of SR beam at the small-angle station for KSRS, Nucl. Instr. Meth. in Phys. Res., 2001, vol. A470, p. 118-121. 5. Malygin A.G. Variations of mice life duration concerning processes of their increasing and ageing. Moscow Society of Naturalists conferences, Gerontology section, 2012, vol. 50, pp. 56-65.

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Prefocussing at PETRA II Beamline P06S. Ritter1, S. Hönig1, C. Baumbach1, J. Patommel1, M. Kahnt1, D.Samberg1, R. Hoppe1, F. Seiboth1, J. Reinhardt2, U. Bösenberg2,

N. Reimers2, G. Wellenreuther2, G. Falkenberg2

and C. G. Schroer1

[1] Institut für Strukturphysik, TU Dresden, D-01062 Dresden, Germany [2] HASYLAB@DESY, Notkestr. 85, D-22607 Hamburg, Germany

[email protected]

INTRODUCTION Hard x-ray microscopy is a powerful method to image structure of small objects. Microscopic setup at PETRA III beamline P06 [1] provides access to different contrast mechanisms such as absorption spectroscopy, fluorescence and (coherent) diffraction. The Beamline is designed to produce hard x-ray beams with sizes of 50 nm (FWHM) and even smaller. Ptychography [2] improves the resolution to below 10 nm for radiation hard samples. A higher flux at the sample can be achieved with prefocusing. It results in shorter exposure times and a better resolution in time and space. For characterize the prefocusing ptychographic scanning coherent diffraction imaging technique is used. RESULTS AND CONCLUSIONS The measurements results weak or no prefocusing leads to high degree of coherence and a low flux in focus. If prefocusing matches transverse coherence length lt to aperture of microscope optic, one capture the available coherent flux and gain high flux. With this setup coherence decreases as the coherent focus size. In addition the Prefocus secondary source shortly before microscope optic creates high flux but a larger incoherent focus. For all that our experiment shows the ptychographic reconstruction [2] with prefocusing is still possible.

In conclusion the theoretical predicts could be confirmed almost. The Beamline P06 at PETRA III provides 2D mapping and 3D scanning tomography, contrast mechanisms like fluorescence or transmission and prefocussing. In the energy range from 10 to 30 keV an resolution between 500 nm and 50 nm. or below with refractive optics [3,4] is feasible. ACKNOWLEDGMENT The authors thank the Beamline stuff for their excellent technical support. The experiments at DESY were carried out as part of the commissioning of Beamline P06 at PETRA III. This work was supported by the BMBF. REFERENCES [1] C. G. Schroer, et al. „Hard X-ray nanoprobe at beamline P06 at PETRA III“ Nucl. Instrum. Methods A, 616, (2009) [2] A. Schropp, et al. „Hard X-Ray Nanobeam Characterization by Coherent Diffraction Microscopy“ Appl. Phys. Lett., 96, (2010) [3] J. Patommel, „Hard X-Ray Scanning Microscope Using Nanofocusing Parabolic Refractive Lenses“, (2010) [4] C. G. Schroer, et al. „Hard x-ray nanoprobe based on refractive x-ray lenses“ Appl. Phys. Lett., 87, (2005)

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High-Resolution Chemical Imaging of Gold Nanoparticles UsingHard X-Ray Ptychography

Juliane Reinhardt(1*,2), Robert Hoppe(2), Georg Hofmann(3),Christian D. Damsgaard(4), Dirk Samberg(2), Jens Patommel(2),

Gerald Falkenberg(1), Gerd Wellenreuther(1), Preety Bhargava(1),Jan-Dierk Grunwaldt(3) and Christian G. Schroer(2)

(1)DESY Notkestraße 85, D-22607 Hamburg, Germany, (2) TU Dresden, Institute of Structural Physics, D-01062 Dresden, Germany,

(3) Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany, (4) Technical University of Denmark, DK-2800 Kgs Lyngby, Denmark

[email protected] INTRODUCTION Probing catalysts during their preparation, activation, and under operating conditions is of great importance for a better understanding and systematic advancements of catalytic reactions [1]. By recording a series of ptychograms at different energies around an absorption edge of an element of interest, the near-edge structure information in terms of absorption and phase shift can be obtained with the same high spatial resolution as seen in the ptychographic reconstruction. The phase shift is quantitively related to the energy-dependent refractive index, which is element specific and also sensitive to the oxidation state and the local chemical environment around an atomic species. As the refraction data has a better signal-to-noise ratio than the absorption for small objects, it is advantageous for chemical nano imaging to make use of the resonant dispersion to evaluate the chemical state of the element of interest. APPROACH In ptychography the sample is scanned through a coherent nanofocused beam (≈ 100 nm FWHM), recording a far-field diffraction pattern at each position of the scan. An appropriate overlap between the illumination at adjacent scan points allows for the unambiguous reconstruction of the complex transmission function of the object by numerical phase retrieval algorithms [2,3]. For this particular

experiment we used nanofocusing parabolic refractive x-ray lenses [4,5]. As proof of principles, we measured a simple model sample. This sample contains gold nanoparticles with a diameter of about 100 nm. A platinum ring serves as marker and reference. The material is located on a Si3N4 membrane window of a TEM grid. RESULTS & DISCUSSION We locally evaluated the phase shift of ptychograms of different energies at the Au-L3

edge. The resonant dispersion is seen for the gold particles in terms of a decrease in the negative phase shift. The phase shift of platinum remains constant, Fig. 1.

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Fig.1 Phase shift of gold and platinum at the Au-L3 edge and a reference absorption spectrum. The negative phase shift decrease is also shown in phase reconstructions at selected energies. Based on the Kramers-Kronig-Relation it is possible to calculate the phase shift from absorption reference data and compare these values to the phase shift in the ptychographic reconstructions. Spatial Resolution The sample geometry is known. Therefore the resolution was determined by comparing simulated gaussian-blurred spheres with the ptychographic reconstruction. The local resolution is about 20 nm. CONCLUSIONS & OUTLOOK It was shown, that it is possible to obtain chemical information from resonant ptychography with a spatial resolution of 20 nm. The maximum resolution depends on the scattering intensity in high scattering angles. Strong scattering features are advantageous. To improve the spatial resolution a high incident flux is required. Therefore prefocusing will be used in the future. To increase the accurancy of the phase shift values a better signal-to-noise ratio has to be achieved by using beamstops. Resonant scanning coherent diffraction imaging has significant advantages over conventional x-ray scanning microscopy, e.g., with transmission or fluorescence contrast. The spatial resolution is unaffected, independent of the chromaticity of the optics [6]. The long-term aim is to investigate nano particles in heterogeneous catalysts in-operando. ACKNOWLEDGMENT The authors thank P. Bhargava, N. Reimers, B. de Samber (DESY), D. Samberg (TU Dresden), A. Fuller, and J. B. Wagner (DTU) for their technical support. This work was supported by the German Ministry of Education and Research (BMBF) under Grant Nos. 05K10OD1 and 05K10VK1 and by VH-VI-403 of the Impuls- und Vernetzungsfonds (IVF) of the Helmholtz Association of German Research Centres. G.H.

was supported by the Helmholtz-Kolleg “Energy Related Catalysis”. Beamtime at beamline P06 at PETRA III was granted within the in-house program of DESY. Gold references were measured at beamline microXAS at synchrotron radiation source SLS at PSI. REFERENCES [1] J.-D. Grunwaldt and C.G. Schroer, Chem. Soc. Rev. 39, 4741 (2010) [2] P. Thibault et al., Ultramicroscopy 109, 338 (2009). [3] A.M. Maiden, J.M. Rodenburg, Ultramicro-scopy 109, 1256 (2009). [4] C.G. Schoer, et al., Appl. Phys. Lett. 82 (9), 1485 (2003). [5] C.G. Schroer et al., Appl. phy. Lett. 87 (12), 124103 (2005). [6] R. Hoppe et al., Appl. Phys. Lett. 102, 203104 (2013).

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Application of XAFS for study Cu, Zn in soilPodkovyrina Yu.S. 1, Soldatov A.V.1, Nevidomskaya D.G.2,

Minkina T.M.31 Southern Federal University, Facultyof Physics, Physics of nanosystems and spectroscopy Department,

040, 5, Sorge st., Rostov-on-Don, 344090, Russia, 2 Institute of Arid Zones of the Southern Scientific Centre RAS, 41,

Chekhov st., Rostov-on-Don, 344006 Russia, 3 Southern Federal University, Faculty of Biology, Soil Science Department, 813, 194/1, prosp. Stachki,

Rostov-on-Don, 344090, Russia [email protected]

INTRODUCTION At present, the growth of industrial production has a major influence on environment pollution. In particular, the soils near the industrial plants are susceptible to contamination by heavy metals. Heavy metals (TM) — are biochemically active technogenic substances that affect on living organisms. In natural conditions, most of these metals are essential trace elements for plants and animals. A toxic effect of TM is shown with an increase in concentration limit. Metals can accumulate in plants and organisms and transmitted in increasing quantities on the food chain. Mercury, zinc, lead, cadmium, arsenic are especially hazardous, since they penetrating with food in humans and higher animals can cause poisoning. The study of contaminated soils is reduced not only to the determination of the concentration of TM, but also identifying the type of compounds (mobile or stable) which the metal could form. X-ray techniques have played a crucial role in finding the answers to many questions related to biology and environment sciences [1]. Study of the extended fine structure of the X-ray absorption spectra (EXAFS) allows to obtain the information about metal-bearing soil phases and to distinguish the interaction type between the metal ions and soil components. In XANES region photoelectrons have a free path (without collision with neighboring atoms), which is longer than in EXAFS region, thus by a multiple scattering process on the surrounding atoms it is possible to determine the 3D atomic structure of metal

ion local environment. Moreover XANES provides information on an oxidation state of an absorbing atom. A combination of both the experimental investigations and the «first principle» calculations was proved as particularly effective [2].

APPROACH Samples. The samples of soil components (calcite, kaolinite, bentonite, preparations of humic acids isolated from ordinary chernozem) were saturated by Zn2+ and Cu2+ ions. The studied samples were placed in a saturated solution of Cu2+ and Zn2+ nitrates. The solution was changed twice a day during a week. The constant level of pH was maintained. One week later, the samples were extracted from the solution and dried. The incubation period of metals in soils and soil components lasted for one year. Experimental and theoretical data. The experimental XANES spectra at the Zn K-edge (9659 eV) and the Cu K-edge (8979 eV) were measured by the laboratory spectrometer Rigaku R-XAS Looper. The data were obtained in the fluorescence mode. Due to the low Cu concentration in the sample of humic acid, which was recovered from an ordinary chernozem, the experimental XANES spectra at the Cu K-edge were recorded at Kurchatov synchrotron radiation source. The calculations were performed using both the finite difference method in full potential FDMNES 2012 [3] and self- consistent method of full multiple scattering in the muffin-tin approximation for the potential FEFF9.54 [4].

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RESULTS AND DISCUSSION The morphology, size, and peculiarities of edge and near-edge areas on XANES spectra of soil samples contaminated by CuO and Cu(NO3)2 have clear differences mainly controlled by the differences in their local atomic structure around the central Cu ion. The spectra of soil samples contaminated by CuO demonstrate close similarity to experimental spectra of the initial copper-bearing compound CuO. By contrast, the spectra of soils treated by Cu(NO3)2 differ significantly from the spectra of the initial copper-bearing compound providing evidence for transformation of the environment of the copper ion introduced into the soil. Copper nitrate is well-soluble in water (pK Cu(NO3)2 = 0,40, pK CuO = — 7,66), because of this, copper ions during the one year of incubation were sorbed by the soil and formed various compounds, including organo-metallic complexes with different functional groups [5]. Analysis of the Zn K-edge XANES spectra for a carbonates soil phase showed that the Zn ions could replace the Ca ions in the octahedral sites, representing the 1s→4p transition. Moreover, they coordinate with Ca ions as ligands, forming an adsorbed complexes on a surface in defects and broken-edge sites. The experimental Cu K-edge XANES spectra for humic acid and Cu(NO3)2 are differs. The intensity of «white line» in the copper nitrate spectrum higher than in the humic acid spectrum. It is observed, that humic acid XANES spectra is broader than spectrum of reference compound. Should be noted that the first derivatives of the Cu XANES spectra reveal more detailed information and show obvious splitting of the and peaks in the edge region. Thus, it suggests that a weak shoulder structure exists in XANES spectra. It is mean that Cu-O and Cu-N distances changed. This fact allows to make a conclusion that octahedral Cu binding sites are tetragonally-distorted. The distortions may occur due to the ion exchange with humic acid functional groups and water molecules. They cannot be caused by the Jahn-Teller effect because it occurs only when all ligands are identical. The outer-sphere

unstable complexes are formed by interactions of Zn2+ ions with functional groups and ligands of humic acid. This result is confirmed with dates of fractionation and previously received results [6]. The research has shown that increasing soil contamination leads to domination of weakly bounded Zn compounds in strongly bounded compounds.

CONCLUSIONS Combining of XANES X-ray absorption spectroscopy and extractive fractionation is effective for establishing connections of metallic ions with soil compounds, as well as identifying the phases-carriers of metals in soils and their bonding strength. Humic acids interact with Zn2+ ions and could form outer-sphere complexes by interacting with the functional groups and ligands, while Cu2+ ions form inner-sphere organometallic complexes. Zn2+ ions replace Ca2+ ions in the octahedral positions and form absorption complexes as ligands with the CO3

2- ions on the surface of the calcite.

REFERENCES [1] A. Prange and H. Modrow, “X-ray absorption spectroscopy and its application in biological , agricultural and environmental research,” pp. 259–276, 2003. [2] Smolentsev G.Y., Soldatov A.V., 2009. Journal of Surface Investigation: X-Ray, Synchrotron and Neutron Techniques.Vol. 3.No 3. pp. 398-401. [3] Bunau O., Joly Y., 2009. J.Phys.:Condens. Matter , V.21, No.34 [4] Rehr J.J., Kas J.J., Vila F.D. Prange M.P. Prange, Jorissen K., (2010) Phys.Chem.Chem.Phys. 12 (21)5503-5513. [5] Minkina T.M., Soldatov A.V. Motuzova G.V., PodkovyrinaYu.S., Nevidomskaya D.G.,2013b. Doklady Earth Science. Vol. 449.Part 2. pp. 418-421. [6] Minkina T. M., Motuzova G. V, Nazarenko O. G., Mandzhieva S.Group. Eurasian Soil Science, 2009. Vol. 42, No. 13. pp. 1–10.

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Phase separation of complex half-doped154Sm0.32Pr0.18Sr0.5MnO3 manganite

G. Sarapin1,2, A. Kurbakov1,2, V. Ryzhov2, C. Martin3, A. Maignan3

1Neutron and Synchrotron Department, Physical Faculty, Saint-Petersburg State University, 2B.P. Konstantinov St. Petersburg Nuclear Physics Institute, National Research Center Kurchatov Institute,

3Laboratoire CRISMAT, Universite de Caen

[email protected]

Earlier, from researches of Sm0.5Sr0.5MnO3 and Pr0.5Sr0.5MnO3 compounds were obtained that the replacement of Sm by Pr or vice versa can drastically change the magneto-transport properties of manganites. By methods of neutron powder diffraction, neutron depolarization, temperature dependences of magnetization, its second harmonic and electrical resistivity was studied the phase separation and microscopic nature of the magnetoresistance in Sm0.32Pr0.18Sr0.5MnO3 manganite. Existence of structural phase transition at 170K from high temperature Pbnm orthorhombic phase to a mixture of two phases: orthorhombic Pbnm and monoclinic Р21/m, with coherently coupled by atomic in the unit cell, but with different lattice parameters was revealed.

Analysis of the magnetic contribution indicates that ground magnetic state is a phase separate with the mixture of three magnetic phases: ferromagnetic (TC ~300К), A-type antiferromagnetic (TN

A ≈ 170К) and

antiferromagnetic charge ordering pseudo-CE-type (TN

CE ≈ 120К) arising because of the strong

competition between the mechanisms of localization and delocalization of charges. F ordering corresponds to the weakly deformed high-temperature Pbnm phase. Both AF states correspond to monoclinic crystal structure, strongly compressed along c-axis. As a result, the microscopic nature of the magnetoresistance, which is reflected in decrease the ρ by several orders at applying magnetic field 7 T is described.

This work was supported by RFBR grant No. 12-02-00073.

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Development and characterization of a new magnetic sampleenvironment for experiments at P10 beamline of

PETRA III facilityAlexander Schavkan1, Fabian Westermeier1, Birgit Fischer1,

Alessandro Ricci1, Martin Schroer1, Gerhard Grübel1,Michael Sprung1

1DESY Deutsches Elektronen-Synchrotron, Hamburg [email protected]

INTRODUCTION The behavior of nanoparticle systems under influence of a tunable parameter is a topic of great interest (“smart nanoparticles”). The goal is to introduce a controlled macroscopic response of the nanoparticle system upon a change of an environmental parameter (e.g. temperature, pressure, magnetic or electric fields). The objective of the experiments described here was the development and characterization of a sample environment with tunable magnetic field.

Fig. 1: Design of the magnetic insert APPROACH The P10 beamline offers a flexible setup to implement special sample environments. The sample chamber is based on a DN100 cube with accessible flanges from 4 sides. Requirements for the magnetic insert design were given by the dimensions of the cube and the possibility to apply magnetic fields parallel and perpendicular to the beam direction as well as change field amplitude and direction. The design consists of

two electromagnets using crossed yokes (see Figure 1). THEORETICAL CALCULATIONS AND CHOICE OF MATERIALS Dimensions for a solenoid were estimated using this design idea. It was decided to manufacture solenoids with a length of and a maximum radius of . A wire with radius was chosen for the solenoid. The yoke can consist of different materials. The chosen material for the first prototype was a HiMu80-alloy by Cartech. This alloy needs only small field to be activated and offers a large permeability. The rods available had a diameter of defining the minimum radius of the coil to be . The magnetizing force of the solenoid was calculated by

(1),

where is the current, is the number of the loops in the solenoid, is the length of the solenoid, is the distance from the end of the coil to the measurement point (estimated in the middle of the solenoid) and are the radii of the different layer of the coil [1]. The magnetizing force of a solenoid with ,

and 23 layers was calculated to , which should provide a saturation

flux density of in the yoke. The flux density in the air gap is defined as

(2),

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where , is the length of the yoke and is the length of the air gap [1]. According to this equation a magnetic field strength of is expected for

. EXPERIMENTAL RESULTS The magnetic chamber was built and tested. The measurements provided the maximum field strength: and

Switching on fields in both directions provided a stronger field with

, which agrees with a theoretical prediction of a field with

under

Hematite particles are known to align under the influence of low magnetic fields starting from

Fig. 2 shows that hematite particles are aligning horizontally and perpendicular to the beam for both applied fields –perpendicular and parallel to the beam, which results in different images on the detector and gives the access to the different dimensions in the investigation of the dynamics[2].

On the other side, Goethite particles are aligning parallel to the field [3]. This is shown with the scattering pattern in fig. 3. CONCLUSIONS The calculations show that magnetic field strength of > 200mT should be possible with the presented design. The experimental results demonstrated that at the moment the design can provide a maximal field strength of

parallel to the beam and perpendicular to the beam. Applying a field of the same strength in both directions provides a field direction in respect to the x-ray beam with a strength of

. The strength of the provided field was enough to align Hematite and the Goethite particles in a water solvent. The design of the magnetic sample environment provides new experimental opportunities due to the implemented possibility to apply the magnetic field parallel to the beam, too. The prototype showed that the design is working according to predictions. Further work is planned to improve the strength of the magnetic field and to provide fast switching capabilities.

REFERENCES [1] L. Bergmann, C. Schäfer. (2006). Elektromagnetismus. Walter de Gruyter. [2] B. J. Lemaire et al. (2005). The complex phase behaviour of suspensions of goethite (α-FeOOH) nanorods in a magnetic field. Faraday Discuss. 128 [3] Ch. Märkert et al. (2010). Small angle scattering from spindle shaped colloidal hematite particles in external magnetic fields. IUCr ACKNOWLEDGEMENTS We want especially recognize the help of Mr. Bernd Hentschel from MKS group at DESY during the manufacturing of the coils and Mr. Kornowski from University Hamburg for the help during the synthesis of the samples and, especially, for the TEM analysis.

Fig. 5: Goethite particles aligned in the field a) perpendicular and b) parallel to the field

Fig. 4: Hematite particles aligned in the field a) perpendicular and b) parallel to the beam

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Two ground states in mixed in mixed Mn1-xFexGe compoundsS.-A. Siegfried1, N. M. Potapova2, E. V. Altenbayev2,3,

V.A. Dyadkin4,2, E. V. Moskvin2,3, V. Dimitriev4, D. Menzel5,C. D. Dewhurst6, D. Chernyshov4, R. A. Sadykov7,8,

L.N. Formicheva7, A. V. Tsvyashchenko7, D. Lott1, A. Schreyer1

and S. V. Grigoriev2,3,1Helmholtz Zentrum Geesthacht, Geesthacht 21502, Germany,

2Petersburg Nuclear Physics Institute, 188300 Gatchina, Saint-Petersburg, Russia, 3 Saint-Petersburg State University, Ulyanovskaya 1, 198504 Saint-Petersburg, Russia,

4Swiss-Norwegian Beamlines at the European Synchrotron Radiation Facility, 38000 Grenoble, France, 5Institut fur Physik der Kondensierten Materie, TU Braunschweig, Braunschweig 38106, Germany,

6Institute Laue-Langevin, 38042 Grenoble Cedex 9, France, 7Institute for High Pressure Physics, Russian Academy of Sciences, 142190 Troitsk, Moscow, Russia,

8Institute for Nuclear Research, Russian Academy of Sciences, 117312 Moscow, Russia [email protected]

The cubic B20 monogermanides belong to the P213 space group. Below Tord pure MnGe and FeGe order in a one-handed helical structure with a propagation vector of k ≈ 2.3 nm-1 for MnGe and k ≈ 0.09 nm-1 for FeGe [1,2,3]. The magnetic properties of these systems are based on a hierarchy of different interactions: the strong ferromagnetic exchange interaction the Dzyaloshinskii-Moriya (DM) interaction, the Anisotropic Exchange (AE) and the cubic anisotropy. The helicity is induced by the DM exchange interaction, due the lack of symmetry of the magnetic atoms in these compounds. The orientation of the spiral is fixed along the principal interaction in these system by the AE interaction and the cubic anisotropy [4,5]. Polycrystalline Mn1-xFexGe samples (0.0 ≤ x ≤ 1.0) have been synthesized by high pressure method [6]. SQUID magnetization measurements were used to establish the magnetic ordering temperature. Tord decreases from x = 0.0 to x = 0.4 from 140 K to 120 K and increases linearly to 278 K for further Fe doping up to 1.0. Small angle neutron scattering (SANS) measurements were carried out the instrument D11 at the Institute Laue Langevin and the SANS-1 at the Meier-Leibnitz-Zentrum (MLZ). The field geometry was always

perpendicular to the incoming neutron beam. The samples with a Fe-doping x ≤ 0.4 behave similar to pure MnGe, while for x > 0.75 it behaves similar to pure FeGe. For the iron doping between 0.45 and 0.75 an additional second state appears. As example the samples with x = 0.6 will be discussed in more details. For field scans at low temperatures a transition from ring-like pattern (fig.1a) (which indicates the coexistence of randomly oriented wavevectors k) to a spot-like pattern with two spots (fig. 1b) in magnetic field direction (k1 || H) is observed due the reorientation of the wavevectors along the external magnetic field direction. The critical field strength is HC1 ≈ 0.15 T. For further field increasing the double scattering in field direction disappears and the remaining peak broads (fig.1c). In field region between HC1 ≈ 0.15 T and HC2 ≈ 0.45 T an intermixed helical state seems to exist. In this region the helical structure oscillates between two ground states with k1 and k2. Above HC2 up to HC3 ≈ 0.6 T the broadened peak contracts again to one thin peak (fig.3d) and just one single helix exists with k2. Finally for fields higher than 0.6 T the helical structures vanishes and the spin structure becomes field aligned. In conclusion we have

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observed a non-trivial field evolution of the magnetic structure in the intermixed compounds Mn1-xFexGe. While for high Fe/Mn concentration the compounds behave like pure FeGe/MnGe, the mean concentration range (0.45 ≤ x ≤ 0.75) giving rise for a second magnetic ground state. [1] N. Kanazawa, et al., Phys. Rev. Lett. 106, 156603 (2011) [2] O. L. Makarova, et al., Phys. Rev. B. 85, 205205 (2012). [3] B. Lebech, et al., J. Phys. Condens. Matter 1, 6105 (1989). [4] I. E. Dzyaloshinskii, Zh. Eksp. Teor. Fiz. 46, 1420 (1964). [5] P. Bak, M. H. Jensen, J. Phys. C13, L881, (1981). [6] A. Tsvyashchenko, et al., Journal of Less Common Metals 99, 2, L9 (1984).

Figure 1: SANS maps for Mn0.4Fe0.6Ge at 30 K: a) 0 T, b) 0.15 T, c) 0.35 T, d) 0.5 T

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Study of the temperature dependencies in ferromagneticinverted opal-like structures by the SQUID-magnetometry

I.S. Shishkin1, A.A. Mistonov1, N.A. Grigoryeva1, D. Menzel2, K.S.Napolskii3, N.A. Sapoletova3, A.A. Eliseev3, S.V. Grigoriev1,4

1Faculty of Physics, Saint Petersburg State University,Russia,2Institut für Physik der Kondensierten Materie Technische Universität,Germany,3Department of Materials Science, Moscow State

University,Russia,4Petersburg Nuclear Physics Institute, Gatchina,Russia [email protected]

The investigations of the magnetic properties of ferromagnetic crystals with the inverted opal structure by the SQUID-magnetometry were performed. Temperature dependencies of the magnetization at the different values of external magnetic field for structured films based on nickel and cobalt with different thicknesses were measured. INTRODUCTION Inverse opal-like structure (IOLS) is a metamaterial, which is producing by the filling of the voids in template opal structure with desired material and subsequent removing of the template. The size and chemical composition of the IOLS are tunable by varying the size of the colloids and the infiltration materials, respectively. IOLS based on ferromagnetic materials are so interesting, because they can be presented as three-dimensional nanoscale analogue of conventional spin ice [1]. Since the spin ice is characterized by the frustrated states of magnetic moments, temperature study of the IOLS magnetic properties is the important fundamental task. Some experiments have already been performed in 2011, and it was shown, that SQUID-magnetometry allows to obtain information about the total magnetization behavior in the IOLS as a function of the angle between the external magnetic field and sample’s plane. SAMPLES AND METHODS Inverse opal-like structures (IOLS) were fabricated by using electrodeposition technique and utilizing a colloidal crystal film as a

template [2]. The colloidal crystal film was prepared by the vertical deposition of monodisperse polystyrene microspheres (D = 530 ± 10 nm) onto a Si(100) wafer coated with a 100 nm-thick gold layer [3]. IOLS as well as the template artificial opal possesses presumably face-centered cubic (fcc) ordering. Thus, all the directions in IOLS are strongly determined. One can consider IO as an assembly of small metallic particles duplicating the shape of the voids between the spheres and connected to each other via thin (several tens of nanometers) and long (several hundreds of nanometers) crosspieces (Fig. 1).

Li et al. Angew. Chem. Int. Ed. 2007, 46

Fig. 1 The base element of an OLS

Fig. 2 The experimental setup –

SQUID-magnetometer

Due to this complicated spatial structure, IOLS possess amazing magnetic properties. Inverse opal-like structures based on Ni and Co were studied. For both materials there were several samples of different thickness – from 0.5 to 26 hexagonal close-packed layers or thickness from 0.25 mkm to 13 mkm. Measurements were carried out with the SQUID-magnetometer

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Quantum Design MPMS-5S, which is located at the Institute Physics of Condensed Matter, Braunschweig, Germany. The scheme of the setup is presented in Fig. 2. Temperature measurements were carried out by the zero-field cooling (ZFC), field-cooling (FC) procedure, when the sample is cooling in zero magnetic field, then heating in some certain field H and after that cooling again in the same field H. The values of magnetic field H of 30, 120 and 200 mT were used. Cooling and heating were done in the temperature range from 3 to 350 K.

RESULTS AND DISCUSSION Temperature dependencies of the magnetization for the sample based on nickel with the thickness of 13 mkm are presented in Fig. 3a.

0 50 100 150 200 250 300 350 4000,0025

0,0050

0,0075

0,0100

0,0125

0,0150

0,0175

0,0200

Ma

gne

tizat

ion

(em

u)

Temperature (K)

ZFC 30 mT FC 30 mT ZFC 120 mT FC 120 mT ZFC 200 mT FC 200 mT

a

0 50 100 150 200 250 300 350 400

0,000

0,002

0,004

0,006

0,008

Mag

netiz

atio

n (e

mu)

Temperature (K)

ZFC 200mT FC 200mT ZFC 120mT FC 120mT ZFC 30mT FC 30mT

b

Fig. 3 Temperature dependence the sample based on nickel (26 layers) (a) and on cobalt (11

layers) (b) One can see, that they have the stepped character. Each curve has its own rate of change of the magnetization, since they have different slope. At low temperatures (3 - 25 K), there is a

feature in the form of magnitude divergence ZFС and FC curves, which decreases with increasing magnetic field. On the ZFC curves in the temperature range 30–55 K the magnetization «jump» is observed. The magnitude of this jump decreases with increasing magnetic field, but its position remains unchanged at the different fields. For all value of fields in the temperature range 60 - 225 K, there is a monotonic increase of the magnetization. For the field of 30 mT in a temperature range 230-270 K is observed the plot with decrease of velocity of magnetization. For fields 120 mT and 200 mT in the same range of temperatures observed constancy of values of magnetization. In Fig. 3b the temperature dependencies of the magnetization for the sample based on cobalt with the thickness of 5.5 mkm are presented. Like in case of the Ni-based sample, these dependencies have the stepped character. At low temperatures, there is a divergence ZFC and FC curves, the value of which depends on the magnetic field. Herewith the larger field leads to the smaller magnitude of the divergence. At the field of 30 mT, the magnetization increases monotonically in the temperature range from 3 to 240 K, when in the range from 240 to 270 K the magnetization «jumps». After that, in the range of 270–350 K the magnetization continues to increase, but with the higher rate. At the field value of 120 mT and 200 mT ZFC curves increase monotonically in the all range of temperature. Enlarging the value of the magnetic field leads to moving of the point of intersection of the ZFC and FC curves to lower temperatures. Unlike the sample based on nickel, which has been described above, in this case the dependence have not a jump in magnetization at the temperature range 30–55 K. CONCLUSION In general, current investigations have shown the influence of the presence of nanostructured material (IOLS), the type of material and the thickness of structure on the total magnetization behavior depending on the temperature. Nature

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of the detected feature is not absolutely clear at the moment, but it seems, that further analysis of the data and additional research will help to resolve this problem.

REFERENCES

[1] A. A. Mistonov, N. A. Grigoryeva, et al., Phys. Rev. B 87, 220408 (2013). [2] K. S. Napolskii, A. Sinitskii, et al., Physica B 397, 23 (2007). [3] S. V. Grigoriev, K. S. Napolskii, N. A. Grigoryeva, et al, Phys. Rev. B 79, 045123 (2009)

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Transverse coherence measurements at P04 beamlineat PETRA III

A.Singer1, P.Skopintsev1,5, J.Bach2, L.Müller1, B.Beyersdorf2,S.Schleitzer1, O.Gorobtsov1, A.Shabalin1, R.Kurta1, D.Dzhigaev1,6,

O.M.Yefanov1, L.Glaser1, A.Sakdinawat3, Y.Liu4, D.Attwood4,G.Grübel1, R.Fromter2, H.P.Oepen2, J.Viefhaus1,

I.A.Vartanyants1,6

1Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany, 2Universität Hamburg, Institut für Angewandte Physik, 20355 Hamburg, Germany,

3SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA, 4University of California, Berkeley, CA 94720, USA,

5NRC “KurchatovInstitute”, 123182 Moscow, Russia, 6National Research Nuclear University, “MEPhI”, 115409 Moscow, Russia

[email protected] INTRODUCTION The experiment for measuring transverse coherence of soft x-ray beam was conducted on P04 Variable Polarization XUV Beamline Station of PETRA III Synchrotron Radiation Source at DESY in Hamburg during commissioning. The undulator period length was adjusted to have resonant energy at 400 eV and the monochromator exit slits separation was varied. We measured vertical transverse coherence of the synchrotron beam with double pinholes apertures, like in classical Young’s experiment. We then have demonstrated that transverse coherence of the beam can be successfully measured with an advanced method utilizing non-redundant arrays (NRA) of slits. THEORY Transverse coherence. An important measure directly related to interference phenomena and describing correlation between two complex values of the electric field E1, E2 at two points in space is complex degree of coherence (CDC). By definition, it is expressed by [1]:

where is the ensemble average and * denotes the complex conjugate. This parameter is a normalized version of the mutual coherence function (MCF) or correlation function of the light field. In the presence of low effects of temporal coherence, i.e. , CDC becomes

or simply and is thereby called the degree of transverse coherence. Multiple slits diffraction. It can be shown [2]

that Fourier transform of the interference pattern observed in N slits diffraction experiment is:

, where is beam intensity at slit , — slits

and separation, — Dirac delta function is Fourier transform of the intensity distribution for single slit diffraction, —

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relative phase, denotes convolution and | | is transverse coherence. If all the distances between the slits are unique, then peaks would be observed in the reciprocal space of the diffraction pattern intensity. If

heights (i.e. maxima of |) of the peaks and and intensities at the slits are known, then a following system of equations might be solved and found for all slits

Figure 1. Typical diffraction image of non-redundant set of five slits at 400 eV and exit slits separation of 50 µm.

Figure 2. Fourier transform of the diffraction pattern. The slits used in the experiment are shown in the upper-right corner of the figure in a box. RESULTS The undulator period length was tuned to have resonant energy at 400 eV. The monochromator slits were separated by 50 or 200 µm. Five and six slits NRA and double pinholes diffraction patterns were collected with a CCD camera and then Fourier transformed (see Fig.1 and 2). Then the degree of vertical transverse coherence was retrieved. In case of diffraction from two apertures the transverse coherence was found on a single distance, whereas in case of multiple apertures (e.g. 5 slits) the transverse coherence was found on several distances (e.g. at ten distances). It was found that exit slits opening reduces the coherence length. For 400 eV beam and slits separation of 50 µm, the coherence length was 8.9 µm (beam FWHM was 20 µm), whereas for slits separation of 200 µm the coherence length was 4.5 µm (beam FWHM 38 µm). The results for beam diffraction on NRA's of slits were identical to those found with double pinholes aperture (see Fig. 3).

Figure 3. Spatial coherence found for 400 eV beam and slits separation of 200 µm measured with double pinholes (gray curve) and five slits NRA (red curve). Beam FWHM is 38 µm. CONCLUSIONS The non-redundant array of slits offer a very useful and rapid method for determination of

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synchrotron beam coherence properties. The technique allows one to measure transverse coherence at several distances at a single exposure. The NRA approach holds correct for undulator radiation and gives the same results as in classical Young’s double pinholes experiment. The NRA method could hold

extremely useful for unstable radiation sources such as free-electron lasers. REFERENCES 1. J.W. Goodman, Statistical optics (Wiley, New York, 1985). 2. Y. Mejia and A. I. Gonzalez, Opt. Commun. (2007), 273, 428

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Spatially resolved orientational order in binary colloid filmsstudied by nano-beam X-ray cross correlation analysis

Martin A. Schroer1, Christian Gutt1, Felix Lehmkühler1, BirgitFischer1, Ingo Steinke1, Alessandro Ricci1, Fabian Westermeier1,

Sebastian Kalbfleisch2, Michael Sprung1, Gerhard Grübel11Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany

2Georg-August-Universität Göttingen, Friederich-Hund-Platz 1,37077 Göttingen, Germany [email protected]

ABSTRACT Scattering techniques are powerful methods for studying soft matter systems. As these samples often lack long range order usual approaches to analyze the two-dimensional scattering patterns only focus on the radially averaged signal. However, often there is a subtle variation of this azimuthal intensity that is lost by the averaging process. Accessing this information allows it to learn more about the underlying orientational order within the sample. Especially, the local heterogeneity of the structure can be explored. This type of information can be determined by the X-ray cross correlation analysis (XCCA) technique [1]. This XCCA approach was used to investigate the local structures of thin films made out of dried binary mixtures of colloids. These films are special types of colloidal crystals. The interest in these structures has increased recently as they can exhibit exciting new properties. For instance, three-dimensional colloidal crystals made out of uniformly-sized colloids can be used as photonic crystals [2]. Their functional properties are related to the underlying crystal structure. Variation of the building-blocks of these artificial crystals allows to tune the characteristic responses to external fields and thus to fabricate tailored materials. Special examples are crystals made out of two types of colloids with different sizes. Such binary colloidal mixtures of particles are known to show a richer phase diagram of crystal structures than single component systems [3]. A detailed knowledge of the local structures of

these ‘colloidal alloys’ is mandatory for the fabrication of materials with dedicated functional properties. In order to investigate the local structure of colloidal films, nano-beam X-ray scattering measurements on dried binary colloidal films of different mixing ratios were performed. The so-obtained two-dimensional small angle X-ray scattering (SAXS) patterns were analyzed with the XCCA technique. This approach allows us to study the local orientational correlations within the colloidal films made out of particles with radius of 11 nm and 19 nm. Due to the nanometer size of the X-ray beam (< 400 x 400 nm2), the orientational correlations of the colloidal films can be spatially resolved. Thus, real space maps of the electron density [4] based on the total scattering intensity, and of local correlations and orientations within the nanoparticle films (based on XCCA) can be obtained. Using such spatial maps the average correlation length within a sample can be measured [5]. This was performed for both the intensity and the cross correlation maps and allows to determine the average extent of correlated regions. In summary, by studying these maps with this ’orientation weighted’ contrast the local structure of the mixtures can be extracted. This information is completely inaccessible by the usual scattering approaches.

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REFERENCES [1] P. Wochner, C. Gutt, T. Autenrieth, T. Demmer, V. Bugaev, A. Diaz Ortiz, A. Duri, F. Zontone, G. Grübel, and H. Dosch, Proc. Natl. Acad. Sci. USA 106, 1151 (2009). [2] A. Blanco et al., Nature 405, 437 (2000). [3] M.H. Kim,S. Hyuk, and O.O. Park, Adv. Mater 17, 2501 (2005).

[4] M. Fratini, N. Poccia, A.Ricci, G. Campi, M. Burghammer, G. Aeppli, A. Bianconi, Nature 466, 841 (2010) [5] A.C.Y. Liu, M.J. Neish, G. Stokol, G.A. Buckley, L.A. Smillie, M.D. de Jonge, R.T. Ott, M.J. Kramer, and B.J. Bourgeois, Phys. Rev. Lett. 110, 205505 (2013)

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Adiabatically Focusing LensesM. Scholz1, J. Patommel1, S. Hönig1, S. Ritter1, A. Jahn2,

C. Richter2, J. W. Bartha2,U. Bösenberg3, G. Falkenberg3

and C. G. Schroer1

1Institute of Structural Physics, TU Dresden, D-01062 Dresden, Germany 2Institute for Semiconductors and Microsystems, TU Dresden, D-01062 Dresden, Germany

3Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany Focusing optics for hard x rays lack of relatively small numerical apertures. In fact, the numerical aperture of all x-ray optics applied so far is limited by the critical angle of total reflection, i. e., their numerical aperture is lower than the square root of twice the refractive decrement. There was the discussion in the x-ray optics community whether this is a fundamental physical limit for any focusing x-ray optic [1]. In [2] the design of a so-called Adiabatically Focusing Lens (AFL) was proposed, a new kind of x-ray lens with a numerical aperture that, at least in theory, exceeds the size of the critical angle of total reflection. The AFL is composed of many single refractive lenses with apertures that are gradually adapted to the size of the converging x-ray beam, allowing to increase the refractive power per length without compromizing the incident aperture of the whole lens. The fabrication of such an AFL is quite challenging, since the size of the single lenses becomes very small. For this reason, no AFL had been realized for quite a long time.

During a cooperation with the Institute for Semiconductors and Microsystems, TU Dresden, we finally succeeded in manufacturing Adiabatically Focusing Lenses made of silicon. We performed an experiment at the nanoprobe endstation of the beamline P06 at PETRA III, where we combined an AFL with a Nanofocusing Lens (NFL) and investigated the beam profile by scanning coherent x-ray diffraction imaging (ptychography). We demonstrated a focus size of 17.1 nm in the vertical direction (generated by the AFL) by 53.4 nm in the horizontal direction (generated by the NFL) at a photon energy of 20 keV. This alone is an outstanding result, as this was is one of the smallest foci that has ever been achieved for hard x rays. Beyond that, the vertical numerical aperture of 1.64 mrad exceeds the critical angle of total reflection of 1.56 mrad for silicon at the used x-ray energy. REFERENCES [1] C. Bergemann, H. Keymeulen, and J. F. van der Veen, Phys. Rev. Lett. 91, 204801 (2001). [2] C. G. Schroer and B. Lengeler, Phys. Rev. Lett. 94, 054802 (2005). * [email protected]

Figure 1: Caustic and beam profile of the focus generated by the AFL/NFL.

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Field induced chirality in helix structure ofmagnet/nonmagnet multilayers

V. Tarnavich1, D. Lott2, S. Mattauch3, V. Kapaklis4, S. Grigoriev1,5

1Petersburg Nuclear Physics Institute, 188300 Gatchina, Russia, [email protected] 2Helmholtz Zentrum Geesthacht, 21502 Geesthacht, Germany

3Jülich Centre for Neutron Science (JCNS), 85747 Garching, Germany 4Uppsala University, Uppsala, Sweden

5 Saint-Petersburg State University, Ulyanovskaya 1, 198504 Saint-Petersburg, Russia Corresponding Author’s Email: [email protected]

The rare-earth magnetism attracted much attention in the light of the discovery of 3D long range order, which can occur in rare earth/yttrium superlattice (SL) structures [1,2,3]. A few years ago we have demonstrated that Dy/Y magnetic multilayer structures (MMLs) possess a coherent spin helix with a preferable chirality induced by the magnetic field [1]. A magnetic field applied in the plane of the sample upon cooling below TN is able to repopulate the otherwise equal population numbers for the left- and right-handed helixes. The experimental results strongly indicate that the chirality is caused by Dzyaloshinskii-Moriya (DM) interaction due to the lack of the symmetry inversion on the interfaces. The polarized neutron reflectometry is used to show that metal magnetic/nonmagnetic (Ho/Y) multilayer structures posses a coherent spin helix propagating through many Ho/Y bilayers. The samples of different thicknesses of Ho and Y layers were grown by molecular-beam-epitaxy techniques: [Ho45Å/Y30Å] (S1), [Ho25Å/Y20Å] (S2), [Ho20Å/Y30Å] (S3), [Ho60Å/Y30Å] (S4), [Ho25Å/Y40Å] (S5). We measured the chirality parameter γ=(I+- I-)/(I+ + I-) of the multilayers as a function of the temperature and magnetic field. This parameter is directly related to the imbalance between the left- and right-handed spiral, where I+/- is the integrated intensity of the helical peak with up (+) and down (-) neutrons. The chirality γ is

equal to 0 for all samples cooled in zero field. The magnetic field of 1 T, applied in the plane of the sample upon cooling below TN, induces non-zero chirality, which almost independent on the temperature for the samples S1, S2, S3. Opposite to it the field does not induce any chirality for samples S4 and S5.

We assume the net chirality in Ho/Y systems appears due to symmetry breaking on magnetic-non-magnetic interface. We expect that the interfacial defects, emerging due to the overlap between magnetic Ho and nonmagnetic Y atoms, can produce a DM interaction normal to the interface in magnetic heterostructures what leads to the predominant chirality, based on the theoretical work of Haraldsen and Fishman [4]. REFERENCES [1] Ross W. Erwin, J. J. Rhyne, M. B. Salamon, J. Borchers, S. Sinha, R. Du, J. E. Cunningham, C. P. Flynn, Phys. Rev. B 35, 6808 (1987). [2] R. A. Cowley, D. F. McMorrow, A. Simpson, D. Jehan, P. Swaddling et al., J. Appl. Phys., Vol. 76, p. 6274-6377 (1994). [3] C. de la Fuente, R. A. Cowley, J. P. Go_; R. C. C. Ward, M. R.Wells, D. F. McMorrow, J. Phys. Condens. Matter, Vol. 11, p. 6529-6541 (1999). [4] J. T. Haraldsen and R. S. Fishman, Phys. Rev. B 81, 020404(R) (2010).

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Structural Investigation of Glasses with MagneticNanoprecipitates

N.N. Trofimova, 1I.S. Edelman,2 O.S. Ivanova,2 R.D. Ivantsov,2E.A. Petrakovskaja,2 D.A. Velikanov,2 V.N. Zabluda,2

and Y.V. Zubavichus2

1 National Research Center “Kurchatov Institute”, Moscow, Russia 2 L.V. Kirensky Institute of Physics SB RAS, Krasnoyarsk, Russia

[email protected] INTRODUCTION Magnetic properties together with optical transparency are remarkable features of oxide glass materials containing magnetic nanoparticles. The nanoparticles are formed during a specific heat treatment and their structure is strongly dependent on initial glass composition and thermal regime. On the other hand, it is the structure of magnetic particles that determines the functional properties of a glass sample. The previous study [1] has revealed that the difference in the magnetic properties of glasses is due to the local order around Fe atoms and size of maghemite (γ-Fe2O3) nanocrystallites. With increasing treatment temperature a distinct long-range order in environment of Fe atoms emerges, whereas the local structure around other dopant atoms (e.g., rare-earth) remains virtually unchanged. Thus, a clear correlation between the local structure of iron atoms and magnetic properties is established. APPROACH The samples under investigation are similar to those previously analyzed. The glass matrix contain Al2O3, GeO2, K2O and B2O3 doped with various additives, including iron, bismuth, yttrium, and rare-earth elements. The XRD data were collected in the Kurchatov Synchroton Radiation Centre in the transmission geometry using Imaging Plate detector, wavelength of radiation was 0.68886 Å, exposure time was about 20 minutes. Also room temperature EMR spectra were recorded.

RESULTS AND DISCUSSION According to the EMR spectra, all samples can be formally divided into three groups (Fig.1) whereas XRD reveals that the glasses can be classified into four groups with different composition of nanocrystalline phase (Fig.2). These groups are A (only maghemite); B1 (maghemite and K2Al2B2O7); B2 (maghemite, YBO3 and δ-Bi2O3); B3 (maghemite and, presumably, PbO).

0 100 200 300 400 500 600

0

500

1000

1500

2000

Inte

nsity

, a.u

.

B, mT

1

2

3

Fig.1- Three types of room temperature EMR spectra.

10 20 30 40

50

100

150

200

250

300

Inte

nsity

, a.u

.

2θ,°

AB1

B2B3

Fig.2 –Four types of diffraction patterns. We observe no clear dependence between the crystallite size, lattice parameter and temperature of treatment. We assume that this is

91


due to the varied composition of the glasses obtained at different temperature and complex effect of additives on the structure formation of maghemite nanoprecipitates. Nonetheless, some common trends in the shape of EPR signal and size of crystallite is observed (Fig.3).

Fig.3 — Correlation between the crystallite size of maghemite phase in group A (top graph) and groups B1, B2, B3 (bottom graph) with the shape of the EMR signal. The value of 2.5 on the abscissa used for samples that have a transitional (between group 2 and group 3) shape of the EMR signal.

CONCLUSIONS XRD data confirm the earlier suggested influence of the crystallite size of maghemite nanoprecipitates on the magnetic properties of the glass samples. Simultaneous modification of glass composition and treatment temperature complicates the analysis to reveal clear correlations. A further study using multi-edge XAFS (EXAFS and XANES) spectroscopy is planned to clarify the «structure-property» relationships. REFERENCES [1] I. Edelman, O. Ivanova, R. Ivantsov, D. Velikanov, V. Zabluda, Y. Zubavichus, A. Veligzhanin,V. Zaikovskiy, S. Stepanov, A. Artemenko, J. Curély and J. Kliava, J. Appl. Phys. 2012, V.112, 084331.

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Fluorescence Properties of CdSe/CdS Nanorods on GoldNanoparticles

Wiebke Friedrich1, Kathrin Hoppe1, and Horst Weller1

1Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany [email protected]

INTRODUCTION Nanoparticles exhibit fascinating optical properties that can be used in various applications. The increasing understanding of these properties opens the door for advanced nanomaterial design.1 Among other areas, the research field on optical properties of gold and semiconductor nanocrystals on the single particle level, such as blinking, quenching and surface plasmon resonances, has grown in the last decades.2,3,4 Although knowledge in this respect has extended greatly, the processes of radiative and non-radiative decay in fluorescing semiconductor nanorods (SNR) on a single particle level still represent a topic with tremendous scientific potential. The investigation of distance dependent electromagnetic field enhancement and quenching sets the basis for further application in photovoltaic technologies. In this work the distance dependent fluorescence intensity of CdSe/CdS nanorods on a gold nanoparticle (GNP) film is studied. The distance dependence of electromagnetic field enhancement by surface plasmon resonances (SPR) of the GNP and quenching by Förster resonance energy transfer (FRET) is determined. FRET describes the mechanism of non-radiative energy transfer between an excited donor and an acceptor in the ground state.5 When looking at metal nanoparticles another effect, the enhancement of the electromagnetic field due to SPR, has to be considered.2,3,4 APPROACH Gold nanoparticle films are prepared by a layer-by-layer spin-coating technique on a glass substrate.6 The highly luminescent SNR are

synthesized by a seeded-growth based hot-injection method.7

A diluted solution of SNR is spin-coated on a glass substrate half covered with a GNP film. The fluorescence intensity of the single SNR is determined using a confocal laser scanning microscope with a single photon counting unit and a spectrometer. Via a polymer film between SPR and GNP film the distance can be adjusted. The polymer film thickness is measured by atomic force microscopy (AFM). In order to study the anisotropic fluorescing properties and geometrical effects on photoluminescence of the SNR it is necessary to determine the energy transfer between an ordered gold nanorod (GNR) assembly –in contrast to GNP films — and the semiconductor nanocrystals. Hence, highly monodisperse GNR are synthesized by a wet-chemical seeded-growth approach.8 Standing assemblies of the GNR are manufactured by a drop-casting technique.9 These arrays represent the substrate for the ongoing measurements on the fluorescence enhancement and quenching of single SNR. RESULTS AND DISCUSSION Depending on the polymer film thickness the fluorescence intensity of the SNR on GNP films

is either enhanced or quenched in comparison to the intensity on glass . The fluorescence intensity is given by:

with the radiative emission rate and the non-radiative energy transfer rate .2,3

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Due to the plasmon resonances, the fluorescence intensity of the SNR on GNP depends on the electromagnetic enhancement factor 2,3:

The normalized intensity is for this system is given by2,3

This correlation leads to the following results of the fluorescence intensity:

Figure 3 graph of the distance dependence of the blinking corrected normalized intensity . Since the SNR show on and off states, the normalized intensity had to be corrected by the respective blinking behavior on GNP films and glass.

As shown in Figure 1, the normalized intensity increases with increasing film thickness. The fluorescence intensity of the SNR on the GNP film exceeds the fluorescence on glass in the measurements with a GNP-SNR distance of roughly above 50 nm. This observation is in accordance to the suggested process of the fluorescence enhancement due to plasmon resonances, although measurements have to be extended to determine the maximum critical distance for the effect. At small SNR-GNP distances the fluorescence is quenched, which confirms the concept of FRET.

CONCLUSIONS AND OUTLOOK A distance dependent quenching and fluorescence enhancement of single SNR on a GNP film was measured. The results are consistent with theoretical concepts.3,4,10 Measurements of the determined effect have to be further evaluated. Currently, the distance dependent quenching and fluorescence enhancement of CdSe/CdS nanorods on ordered GNR assemblies is investigated. Thus, polarization effects or even an angular dependence of the optical properties can be determined using the concept of Chance, Prock and Silbey and the presented setup.11 REFERENCES (1) Guerrero-Martínez, A.; Grzelczak, M.; Liz-Marzán, L. ACS Nano 2012, 6, 3655-3662. (2) Govorov, A.O.; Bryant, G.W.; Zhang, W.; Skeini, J.L.; Kotov, N.A.; Slocik, J.M.; Naik, R.R. Nano Lett. 2006, 6, 984-994. (3) Ito, Y.; Matsuda, K.; Kanemitsu, Y. Phys. Rev. B 2007, 75, 033309-033313. (4) Fu, Y; Lakowicz, J.R. Laser & Photon. Rev. 2009, 3, 221-232. (5) Forster, T Discuss. Faraday Soc. 1959, 27, 7-17. (6) Schlicke, H.; Schröder, J.H.; Trebbin, M.; Petrov, A.; Ijeh, M.; Weller, H. Vossmeyer, T. Nanotechnology 2011, 22, 305303-305312. (7) Carbone, L.; Nobile, C.; De Giorgi, M.; Della Sala, F.; Morello, G.; Pompa, P.; Hytch, M.; Snoeck, E.; Fiore, A.; Franchini, I.R.; Nadasan, M.; Silvestre, A.F.; Chiodo, L.; Kudera, S.; Cingolani, R.; Krahne, R.; Manna, L. Nano Lett. 2007, 7, 2942-2950. (8) Ye, X.; Zheng, C.; Chen, J.; Gao, Y.; Murray, C.B. Nano Lett. 2013, 13, 765-771. (9) Sreeprasad, T.S.; Samal, A.K.; Pradeep, T. Langmuir 2008, 24, 4589-4599. (10) Jander, S.; Kornowski, A.; Weller, H. Nano Lett. 2011, 11, 5179-5183. (11) Chance, R.R.; Prock, A.; Silbey, R. J, Chem. Phys. 1976, 65, 2527-2531.

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................................................................................................................................- 5 -

RACIRI SUMMER SCHOOL-PROGRAM.......................................................................................................................- 5 -

TWO ASPECTS OF MY RESEARCH IN THE FIELD OF SCATTERING ................................................................... 10

ADLMANN FRANZ1 ................................................................................................................................................................ 10

MAGNETIC STRUCTURE OF MNGE IN A WIDE TEMPERATURE RANGE........................................................... 11

E. V. ALTYNBAYEV1,2, S.-A. SIEGFRIED

3, N.M. POTAPOVA1, V. A. DYADKIN

1,4, E. V. MOSKVIN1,2, D. MENZEL

5, CH. DEWHURST

6, R.A. SADYKOV7,8, L.N. FOMICHEVA

8, A.V. TSVYASHCHENKO8, S. V. GRIGORIEV

1,2....................................... 11

STRUCTURE OF THE VANADIUM — DOPED ND5MO3OY SINGLE CRYSTAL.................................................... 13

A.M. ANTIPIN1, O.A. ALEKSEEVA

1, N.I. SOROKINA1, E.P. KHARITONOVA

2, V.I. VORONKOVA2 .......................................... 13

APPLICATION OF THE METHOD OF NEUTRON ACTIVATION ANALYSIS FOR DETERMINATION OF NANOPARTICLES TRANSPORT PROPERTIES IN BIOLOGICAL TISSUES IN VIVO.......................................... 14

А.А. ANTSIFEROVA¹.............................................................................................................................................................. 14

INDUSTRIAL APPLICATIONS OF SYNCHROTRON RADIATION............................................................................ 16

G.A. APPLEBY....................................................................................................................................................................... 16

DEVELOPMENT OF THE METHOD FOR TIME RESOLVING OBSERVATION OF ROCKING CURVES BY ULTRASONIC MODULATION OF THE LATTICE PARAMETER.............................................................................. 17

A.E. BLAGOV1, A.V. TARGONSKY

1, P.A. PROSEKOV1, YU. V. PISAREVSKY

1, M.V. KOVALCHUK 1,2 ................................... 17

TRANSPORT PROPERTIES OF THE LA0.75CA0.25MNO3 MANGANITE ................................................................ 18

I.A. BONDAREV1 AND N.V. VOLKOV

1,2 ................................................................................................................................. 18

DIELECTRIC GLASS-CERAMICS FOR MOBILE APPLICATIONS IN THE GHZ FREQUENCY RANGE......... 19

HUBERTUS BRAUN1,2,3, MARTIN LETZ

1, HANS-JOACHIM ELMERS2,3, MARTUN HOVHANNISYAN

1,4 ....................................... 19

POROSITY CHARACTERIZATION OF UHMWPE-DERIVED MATERIALS FOR MEDICAL APPLICATION. 20

IU.BYKOVA 1, V.ALTAPOVA

1,3, S.LEBEDEV 1, T.BAUMBACH

2,3, I.KHLUSOV 1,4

AND V.F. PICHUGIN 1 .................................. 20

STRUCTURE AND SELF-ORGANIZATIONIN MAGNETIC LIQUIDS....................................................................... 23

HAUKE CARSTENSEN, MAX WOLFF, VASSILIOS KAPAKLIS................................................................................................... 23

COMPARATIVE MORPHOLOGY OF MACROMOLECULES OF IMMUNOGLOBULIN-M AND HUMAN RHEUMATOID FACTOR FROM SAXS DATA ................................................................................................................ 24

DENIZA I. CHEKRYGINA1, VLADIMIR V. VOLKOV

1, VICTOR A. LAPUK2, ELENA YU. VARLAMOVA

3 .................................... 24

SURFACE MODIFICATION OF METAL OXIDE NANOPARTICLES THROUGH CONTROLLED RADICAL POLYMERIZATION FOR IMPROVING ELECTRICAL INSULATION IN HVDC CABLES .................................. 27

CARMEN COBO SÁNCHEZ, MARTIN WÅHLANDER, LINDA FOGELSTRÖM, ANNA CARLMARK, ULF GEDDE, EVA

MALMSTRÖM1 ....................................................................................................................................................................... 27

SAXS DERIVED 3D-MODEL OF THE NOVEL BACTERIAL FRUCTOSE 1,6-BISPHOSPHATE ALDOLASE.... 28

L.A. DADINOVA1, E.V. RODINA

2, N.N. VOROBIEBA2, E.V. SHTYKOVA

1 ............................................................................... 28

95


STRUCTURAL, OPTICAL AND ELECTRICAL PROPERTIES OF AMORPHOUS SILICON MODIFIED BY FEMTOSECOND LASER RADIATION ............................................................................................................................. 30

A.V. EMELYANOV1,2, P.A. FORSH

1,2, P.K., A.G. KAZANSKII2, M.V. KHENKIN

2, KASHKAROV1,2, P.G. KAZANSKY

3 .............. 30

STRUCTURE OF LUMINESCENT GLUCONACETOBACTER XYLINUS CELLULOSE NANOCOMPOSITES INVESTIGATED BY SMALL ANGLE SCATTERING .................................................................................................... 33

EZDAKOVA K1, KOPITSA G.1, SMYSLOV R.2, BUGROV A.2, NEKRASOVA T.2, KHRIPUNOV A.2 , ANGELOV B.3 PIPICH V.4, SZEKELY N.4 ......................................................................................................................................................................... 33

ORIENTATIONAL ORDERING AND PACKING EFFECTS OF SPINDLE SHAPED PARTICLES INVESTIGATED BY SPATIALLY RESOLVED COHERENT SAXS ............................................................................ 35

B. FISCHER 1,2, C.GUTT

1,2, J. WAGNER 3, F. LEHMKÜHLER

1,2, C. PASSOW 3, M. SPRUNG

1,G. GRÜBEL12, .............................. 35

HIGHLY ORDERED MOLECULAR MATERIALS STUDIED BY SYNCHROTRON TECHNIQUES .................... 37

STEFAN FISCHER, JOSEF HIRTE, BERT NICKEL1..................................................................................................................... 37

SPECTROMETER FOR HARD XFEL BASED ON DIFFRACTION FOCUSING........................................................ 38

O. Y. GOROBTSOV1,2, V. G. KOHN

1 AND I. A. VARTANYANTS

2,3 ........................................................................................... 38

EXAFS AND XRD STUDIES OF TI50NI25CU25 SHAPE MEMORY ALLOY AT THE MARTENSITIC TRANSFORMATION ............................................................................................................................................................ 39

ALEXEY MENUSHENKOV1, OLGA GRISHINA

1, ALEXANDER SHELYAKOV, ALEXANDER YAROSLAVTSEV, NIKOLAY

SITNIKOV1, YAN ZUBAVICHUS

2, ALEXEY VELIGZHANIN2, JOSEPH BEDNARCIK

3, ROMAN CHERNIKOV3................................ 39

COMBINED ELECTRICAL AND GRAZING INCIDENCE X-RAY MEASUREMENTS OF POLY(3-HEXYLTHIOPHENE) THIN FILM FORMATION........................................................................................................... 41

LINDA GRODD1, ULLRICH PIETSCH

1, SOUREN GRIGORIAN1................................................................................................... 41

THERMOTROPIC PHASE TRANSITIONS IN MODEL LIPID MEMBRANES BASED ON CERAMIDE 6: PH INFLUENCE ........................................................................................................................................................................... 43

A.YU. GRUZINOV1, M.A.KISELEV

2, E.V. ERMAKOVA2, A.V. ZABELIN

1................................................................................ 43

HARD X-RAY NANOPROBE AT BEAMLINE P06 AT PETRA III................................................................................ 44

R.HOPPE1, A. GOLDSCHMIDT

1, F. SEIBOTH1, P. BOYE

1, J.M. FELDKAMP1, J. PATOMMEL

1, D. SAMBERG1, A. SCHROPP

1, S. RITTER

1, V. MEIER1, S. HÖNIG

1, C. BAUMBACH1, A. SCHWAB

1, S. STEPHAN1, G. FALKENBERG

2, G. WELLENREUTHER2, N.

REIMERS2, P. BHARGAVA

2, T. CLAUßEN2, J. REINHARDT

2 AND C.G. SCHROER

1,.................................................................... 44

FABRICATION AND QUALITY CONTROL OF THE X-RAY DIFFRACTION GRATINGS AT ANKA ................ 45

D. KARPOV1, V. WEINHARDT

1,2, D. KUNKA3, F. CHEN

1, T. BAUMBACH1............................................................................... 45

STUDY OF SILICON-ON-SAPPHIRE STRUCTURAL QUALITY BY X-RAY DIFFRACTOMETRY, REFLECTIVITY AND TEM METHODS............................................................................................................................ 48

BLAGOV A.E.1, VASILIEV A.L.1, KONDRATEV O.A.1, PISAREVSKIY YU.V.1, PROSEKOV P.A.1, SEREGIN A.YU.1 ................. 48

MONTE-CARLO SIMULATIONS OF THERMAL NEUTRON FILTER AND NEUTRON GUIDE SYSTEM FOR REVERANS REFLECTOMETER ....................................................................................................................................... 50

P. KONIK1, E. MOSKVIN

1,2 ..................................................................................................................................................... 50

INFLUENCE OF RADIATION DOSE ON THE STRUCTURE OF CYTOCHROME C NITRITEREDUCTASE.... 51

LAZARENKO VLADIMIR1, POLYAKOV KONSTANTIN

2............................................................................................................. 51

PHASE DYNAMICS OF JOSEPHSON JUNCTIONS........................................................................................................ 53

S. YU. MEDVEDEVA1,2

AND YU. M. SHUKRINOV 1 ................................................................................................................. 53

THREE-DIMENSIONAL ARTIFICIAL SPIN ICE IN NANOSTRUCTURED CO ON AN INVERSE OPAL-LIKE LATTICE................................................................................................................................................................................. 55

96


A.A. MISTONOV1, N.A. GRIGORYEVA

1, H. ECKERLEBE2, N.A. SAPOLETOVA

3, K.S. NAPOLSKII3, A.A. ELISEEV

3, D. MENZEL

4, S.V. GRIGORIEV1,5 ........................................................................................................................................... 55

APPLYING THE SYNCHROTRON RADIATION FOR THE STUDYING PHASE-FORMATION DURING COMBUSTION OF THE ALUMINUM NANOPOWDER IN AIR................................................................................... 57

ANDREY V. MOSTOVSHCHIKOV, ALEXANDER P. ILYIN, NIKOLAY A. TIMCHENKO............................................................... 57

STRUCTURE OF SUPPORTED CATALYSTS: X-RAY SYNCHROTRON DIAGNOSTICS IN SITU ...................... 60

MURZIN V.Y.1, 2, ZUBAVICHUS Y.V.1, VELIGZHANIN A.A.1, BRUK L.G.3, BUKHTIYAROV V.I.4............................................ 60

PRESSURE-INDUCED PHASE TRANSITIONS IN THE LANGASITE STRUCTURE COMPOUND BA3TAFE3SI2O14.................................................................................................................................................................. 63

P. G. NAUMOV1,2, I. S. LYUBUTIN

1, V. KSENOFONTOV2, S. MEDVEDYEV

3 AND C. FELSER

3................................................... 63

GRAFTED POLYLACTIDE PARTICLES AND THEIR REPULSIVE FORCES ......................................................... 66

ROBERTUS WAHYU N. NUGROHO, TORBJÖRN PETTERSSON, KARIN ODELIUS, ANDERS HÖGLUND, AND ANN-CHRISTINE

ALBERTSSON......................................................................................................................................................................... 66

THE REACTION OF DECOMPOSITION OF MNB2H8 ................................................................................................... 67

PANKIN ILYA1, GUDA ALEXANDER

1, FILINCHUK YAROSLAV 2, SOLDATOV ALEXANDER

1 ................................................... 67

MÖSSBAUER STUDY OF THE FESETE COMPOUND SYSTEM................................................................................. 69

PERUNOV I.V. 1, FROLOV K.V.1, VASYUKOV D.M.1,LYUBUTIN I.S.1, KOROTKOV N.YU.1, BELIKOV V.V.2, KASAKOV S.M.2, ANTIPOV E.V.2 ...................................................................................................................................................................... 69

STUDY OF NANOSTRUCTURAL ORGANIZATION OF ANIMAL HAIR BIOLOGICAL FIBER WITH X-RAY DIFFRACTION METHODS USING SYNCHROTRON RADIATION ........................................................................... 70

A.YU. GRUZINOV1, A.A. VASILYEVA

2 G.S. PETERS

1, V.V. STEPANOVA2 I.A. STAROSELSKIY

1,3 A.V. ZABELIN

1,2, A.G. MALYGIN

4 A.A. VAZINA

1,2.................................................................................................................................................... 70

PREFOCUSSING AT PETRA II BEAMLINE P06............................................................................................................. 72

S. RITTER1, S. HÖNIG

1, C. BAUMBACH1, J. PATOMMEL

1, M. KAHNT1, D. SAMBERG

1, R. HOPPE1, F. SEIBOTH

1, J. REINHARDT2,

U. BÖSENBERG2, N. REIMERS

2, G. WELLENREUTHER2, G. FALKENBERG

2 AND C. G. SCHROER

1 ........................................... 72

HIGH-RESOLUTION CHEMICAL IMAGING OF GOLD NANOPARTICLES USING HARD X-RAY PTYCHOGRAPHY ................................................................................................................................................................ 73

JULIANE REINHARDT(1*,2), ROBERT HOPPE

(2), GEORG HOFMANN(3), CHRISTIAN D. DAMSGAARD

(4), DIRK SAMBERG(2), JENS

PATOMMEL(2), GERALD FALKENBERG

(1), GERD WELLENREUTHER(1), PREETY BHARGAVA

(1), JAN-DIERK GRUNWALDT(3)

AND

CHRISTIAN G. SCHROER(2) ..................................................................................................................................................... 73

APPLICATION OF XAFS FOR STUDY CU, ZN IN SOIL ............................................................................................... 75

PODKOVYRINA YU.S. 1, SOLDATOV A.V.1, NEVIDOMSKAYA D.G.2, MINKINA T.M.3 ............................................................ 75

PHASE SEPARATION OF COMPLEX HALF-DOPED 154SM0.32PR0.18SR0.5MNO3 MANGANITE............................. 77

G. SARAPIN1,2, A. KURBAKOV

1,2, V. RYZHOV2, C. MARTIN

3, A. MAIGNAN3 ......................................................................... 77

DEVELOPMENT AND CHARACTERIZATION OF A NEW MAGNETIC SAMPLE ENVIRONMENT FOR EXPERIMENTS AT P10 BEAMLINE OF PETRA III FACILITY .................................................................................. 78

ALEXANDER SCHAVKAN1, FABIAN WESTERMEIER

1, BIRGIT FISCHER1, ALESSANDRO RICCI

1, MARTIN SCHROER1, GERHARD

GRÜBEL1, MICHAEL SPRUNG

1 ............................................................................................................................................... 78

TWO GROUND STATES IN MIXED IN MIXED MN1-XFEXGE COMPOUNDS........................................................... 80

S.-A. SIEGFRIED1, N. M. POTAPOVA

2, E. V. ALTENBAYEV2,3, V.A. DYADKIN

4,2, E. V. MOSKVIN2,3, V. DIMITRIEV

4, D. MENZEL

5, C. D. DEWHURST6, D. CHERNYSHOV

4, R. A. SADYKOV7,8, L.N. FORMICHEVA

7, A. V. TSVYASHCHENKO7, D.

LOTT1, A. SCHREYER

1 AND S. V. GRIGORIEV

2,3, .................................................................................................................... 80

STUDY OF THE TEMPERATURE DEPENDENCIES IN FERROMAGNETIC INVERTED OPAL-LIKE STRUCTURES BY THE SQUID-MAGNETOMETRY...................................................................................................... 82

97


I.S. SHISHKIN1, A.A. MISTONOV

1, N.A. GRIGORYEVA1, D. MENZEL

2, K.S. NAPOLSKII3, N.A. SAPOLETOVA

3, A.A. ELISEEV3,

S.V. GRIGORIEV1,4................................................................................................................................................................. 82

TRANSVERSE COHERENCE MEASUREMENTS AT P04 BEAMLINE AT PETRA III ........................................... 85

A.SINGER1, P.SKOPINTSEV

1,5, J.BACH2, L.MÜLLER

1, B.BEYERSDORF2, S.SCHLEITZER

1, O.GOROBTSOV1, A.SHABALIN

1, R.KURTA

1, D.DZHIGAEV1,6, O.M.YEFANOV

1, L.GLASER1, A.SAKDINAWAT

3, Y.LIU4, D.ATTWOOD

4, G.GRÜBEL1,

R.FROMTER2, H.P.OEPEN

2, J.VIEFHAUS1, I.A.VARTANYANTS

1,6 ........................................................................................... 85

SPATIALLY RESOLVED ORIENTATIONAL ORDER IN BINARY COLLOID FILMS STUDIED BY NANO-BEAM X-RAY CROSS CORRELATION ANALYSIS....................................................................................................... 88

MARTIN A. SCHROER1, CHRISTIAN GUTT

1, FELIX LEHMKÜHLER1, BIRGIT FISCHER

1, INGO STEINKE1, ALESSANDRO RICCI

1, FABIAN WESTERMEIER

1, SEBASTIAN KALBFLEISCH2, MICHAEL SPRUNG

1, GERHARD GRÜBEL1 ........................................... 88

ADIABATICALLY FOCUSING LENSES........................................................................................................................... 90

M. SCHOLZ*1, J. PATOMMEL1, S. HÖNIG

1, S. RITTER1, A. JAHN

2, C. RICHTER2, J. W. BARTHA

2,U. BÖSENBERG3, G.

FALKENBERG3 AND C. G. SCHROER

1 ..................................................................................................................................... 90

FIELD INDUCED CHIRALITY IN HELIX STRUCTURE OF MAGNET/NONMAGNET MULTILAYERS........... 91

V. TARNAVICH1, D. LOTT

2, S. MATTAUCH3, V. KAPAKLIS

4, S. GRIGORIEV1,5 ........................................................................ 91

STRUCTURAL INVESTIGATION OF GLASSES WITH MAGNETIC NANOPRECIPITATES ............................... 92

N.N. TROFIMOVA, 1I.S. EDELMAN,2 O.S. IVANOVA,2 R.D. IVANTSOV,2 E.A. PETRAKOVSKAJA,2 D.A. VELIKANOV,2 V.N. ZABLUDA,2 AND Y.V. ZUBAVICHUS

2..................................................................................................................................... 92

FLUORESCENCE PROPERTIES OF CDSE/CDS NANORODS ON GOLD NANOPARTICLES.............................. 94

WIEBKE FRIEDRICH1, KATHRIN HOPPE

1, AND HORST WELLER1 ............................................................................................ 94

98

Advanced Materials Design at X-ray and Neutron Facilities

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