TY - JOUR A1 - Sulyanova, Elena A. A1 - Shabalin, Anatoly A1 - Zozulya, Alexey V. A1 - Meijer, Janne-Mieke A1 - Dzhigaev, Dmitry A1 - Gorobtsov, Oleg A1 - Kurta, Ruslan P. A1 - Lazarev, Sergey A1 - Lorenz, Ulf A1 - Singer, Andrej A1 - Yefanov, Oleksandr A1 - Zaluzhnyy, Ivan A1 - Besedin, Ilya A1 - Sprung, Michael A1 - Petukhov, Andrei V. A1 - Vartanyants, Ivan A. T1 - Structural Evolution of Colloidal Crystal Films in the Process of Melting Revealed by Bragg Peak Analysis JF - Langmuir N2 - In situ X-ray diffraction studies of structural evolution of colloidal crystal films formed by polystyrene spherical particles upon incremental heating are reported. The Bragg peak parameters, such as peak position, integrated intensity, and radial and azimuthal widths were analyzed as a function of temperature. A quantitative study of colloidal crystal lattice distortions and mosaic spread as a function of temperature was carried out using Williamson-Hall plots based on mosaic block model. The temperature dependence of the diameter of polystyrene particles was obtained from the analysis of Bragg peaks, and the form factor contribution extracted from the diffraction patterns. Four stages of structural evolution in a colloidal crystal upon heating were identified. Based on this analysis, a model of the heating and melting process in the colloidal crystal film is suggested. Y1 - 2015 U6 - https://doi.org/10.1021/la504652z SN - 0743-7463 VL - 31 IS - 19 SP - 5274 EP - 5283 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Gorobtsov, Oleg Yu. A1 - Lorenz, Ulf A1 - Kabachnik, Nicolai M. A1 - Vartanyants, Ivan A. T1 - Theoretical study of electronic damage in single-particle imaging experiments at x-ray free-electron lasers for pulse durations from 0.1 to 10 fs JF - Physical review : E, Statistical, nonlinear and soft matter physics N2 - X-ray free-electron lasers (XFELs) may allow us to employ the single-particle imaging (SPI) method to determine the structure of macromolecules that do not form stable crystals. Ultrashort pulses of 10 fs and less allow us to outrun complete disintegration by Coulomb explosion and minimize radiation damage due to nuclear motion, but electronic damage is still present. The major contribution to the electronic damage comes from the plasma generated in the sample that is strongly dependent on the amount of Auger ionization. Since the Auger process has a characteristic time scale on the order of femtoseconds, one may expect that its contribution will be significantly reduced for attosecond pulses. Here we study the effect of electronic damage on the SPI at pulse durations from 0.1 to 10 fs and in a large range of XFEL fluences to determine optimal conditions for imaging of biological samples. We analyzed the contribution of different electronic excitation processes and found that at fluences higher than 1013-1015 photons/mu m(2) (depending on the photon energy and pulse duration) the diffracted signal saturates and does not increase further. A significant gain in the signal is obtained by reducing the pulse duration from 10 to 1 fs. Pulses below a duration of 1 fs do not give a significant gain in the scattering signal in comparison with 1-fs pulses. We also study the limits imposed on SPI by Compton scattering. Y1 - 2015 U6 - https://doi.org/10.1103/PhysRevE.91.062712 SN - 1539-3755 SN - 1550-2376 VL - 91 IS - 6 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Pietsch, Ullrich A1 - Grigorian, Souren A. A1 - Grenzer, Jörg A1 - Vartanyants, Ivan A. T1 - Thermal diffuse scattering in grazing incidence diffraction Y1 - 2003 ER - TY - JOUR A1 - Pietsch, Ullrich A1 - Panzner, Tobias A1 - Leitenberger, Wolfram A1 - Vartanyants, Ivan A. T1 - Coherence experiments using white synchrotron radiation N2 - Experiments at the bending magnet beamline at BESSY II (EDR beamline) profit from the excellent coherence properties of third generation synchrotron sources. Considering the exponentially decaying incident spectrum, and because no optical elements are installed except slits and vacuum windows, coherence experiments can be performed between 5 keV < E < 15 keV. First, the energy dependence of spatial coherence properties were determined measuring diffraction at single and double pinholes. Next, the coherent white radiation was used to probe the morphology of thin films in reflection geometry. The recorded intensity maps (reflectivity versus sample position) provide speckle patterns which reveal the locally varying sample morphology. Setting the incident angle, alpha(i), smaller or larger than the critical angle of total external reflection, alpha(c), one should be able to separate the surface height profile from the subsurface density modulation of a sample. The validity of this approach is verified at the example of reciprocal space maps taken from a polymer surface where we could reconstruct the lateral height profile from speckle data. (C) 2004 Elsevier B.V. All rights reserved Y1 - 2005 ER - TY - JOUR A1 - Pietsch, Ullrich A1 - Panzner, Tobias A1 - Leitenberger, Wolfram A1 - Vartanyants, Ivan A. T1 - Coherence experiments at the EDR-beamline of BESSY II Y1 - 2005 ER -