TY - JOUR A1 - Reiche, Jürgen A1 - Pietsch, Ullrich A1 - Fink, Hans-Peter A1 - Lemmetyinen, Helge T1 - A comparison fo x-ray methods for structure refinement of Langmuir-Blodgett multilayers N2 - The possibilities and limits of structure refinement of Langmuir-Blodgett films by means of symmetrical reflection of X- rays are described using the example of a stearic acid multilayer. Three different techniques for the determiantion of the electron density profile from reflectivity data are compared; a Fourier method, a Patterson method, and model calculations. The important role of the a priori information for finding the besft structure model is outlined. Y1 - 1992 ER - TY - JOUR A1 - Pietsch, Ullrich A1 - Hansen, N. K. T1 - A critical review of the valence charge density in GaAs Y1 - 1996 ER - TY - JOUR A1 - Leitenberger, Wolfram A1 - Pietsch, Ullrich T1 - A monolithic Fresnel bimirror for hard X-rays and its application for coherence measurements N2 - Experiments using a simple X-ray interferometer to measure the degree of spatial coherence of hard X-rays are reported. A monolithic Fresnel bimirror is used at small incidence angles to investigate synchrotron radiation in the energy interval 5-50 keV with monochromatic and white beam. The experimental setup was equivalent to a Young's double-slit experiment for hard X-rays with slit dimensions in the micrometre range. From the high-contrast interference pattern the degree of coherence was determined. Y1 - 2007 UR - http://journals.iucr.org/s/issues/2007/02/00/wl5137/wl5137.pdf U6 - https://doi.org/10.1107/S0909049507003846 SN - 0909-0495 ER - TY - JOUR A1 - Lichanot, Albert A1 - Azavant, P. A1 - Pietsch, Ullrich T1 - Ab-initio Hartree-Fock study of the electronic charge density of the cubic boron nitride and its comparison with the experiment Y1 - 1996 ER - TY - JOUR A1 - Stahn, Jochen A1 - Möhle, Marcus A1 - Pietsch, Ullrich T1 - Accurate structure determination for GaAs using Pendellösung oscillation Y1 - 1996 ER - TY - JOUR A1 - Herrmann, A. A1 - Kaupp, G. A1 - Geue, Thomas A1 - Pietsch, Ullrich T1 - AFM and GID investigations of the gas-solid diazotation of 4-sulfanil-acid-monohydrat single crystals Y1 - 1997 ER - TY - JOUR A1 - Send, Sebastian A1 - Abboud, Ali A1 - Leitenberger, Wolfram A1 - Weiss, Manfred S. A1 - Hartmann, Robert A1 - Strüder, Lothar A1 - Pietsch, Ullrich T1 - Analysis of polycrystallinity in hen egg-white lysozyme using a pnCCD JF - Journal of applied crystallography N2 - A crystal of hen egg-white lysozyme was analyzed by means of energy-dispersive X-ray Laue diffraction with white synchrotron radiation at 2.7 angstrom resolution using a pnCCD detector. From Laue spots measured in a single exposure of the arbitrarily oriented crystal, the lattice constants of the tetragonal unit cell could be extracted with an accuracy of about 2.5%. Scanning across the sample surface, Laue images with split reflections were recorded at various positions. The corresponding diffraction patterns were generated by two crystalline domains with a tilt of about 1 degrees relative to each other. The obtained results demonstrate the potential of the pnCCD for fast X-ray screening of crystals of macromolecules or proteins prior to conventional X-ray structure analysis. The described experiment can be automatized to quantitatively characterize imperfect single crystals or polycrystals. Y1 - 2012 U6 - https://doi.org/10.1107/S0021889812015038 SN - 0021-8898 VL - 45 IS - 6 SP - 517 EP - 522 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Pietsch, Ullrich A1 - Darowski, Nora A1 - Ulyanenkov, A. A1 - Grenzer, Jörg A1 - Wang, K. H. A1 - Forchel, Alfred T1 - Analysis of the strain distribution in lateral nanostructures for interpreting photoluminescence data Y1 - 2000 ER - TY - JOUR A1 - Leitenberger, Wolfram A1 - Hartmann, Robert A1 - Pietsch, Ullrich A1 - Andritschke, Robert A1 - Starke, Ines A1 - Strüder, Lothar T1 - Application of a pnCCD in X-ray diffraction : a three-dimensional X-ray detector N2 - The first application of a pnCCD detector for X-ray scattering experiments using white synchrotron radiation at BESSY II is presented. A Cd arachidate multilayer was investigated in reflection geometry within the energy range 7 keV < E < 35 keV. At fixed angle of incidence the two-dimensional diffraction pattern containing several multilayer Bragg peaks and respective diffuse-resonant Bragg sheets were observed. Since every pixel of the detector is able to determine the energy of every incoming photon with a resolution Delta E/E similar or equal to 10(-2). a three-dimensional dataset is finally obtained. In order to achieve this energy resolution the detector was operated in the so-called single-photon- counting mode. A full dataset was evaluated taking into account all photons recorded within 10(5) detector frames at a readout rate of 200 Hz. By representing the data in reciprocal-space coordinates, it becomes obvious that this experiment with the pnCCD detector provides the same information as that obtained by combining a large number of monochromatic scattering experiments using conventional area detectors. Y1 - 2008 UR - http://onlinelibrary.wiley.com/iucr/10.1107/S0909049508018931 U6 - https://doi.org/10.1107/S0909049508018931 ER - TY - JOUR A1 - Henneberg, Oliver A1 - Chi, Li Feng A1 - Geue, Thomas A1 - Saphiannikova, Marina A1 - Pietsch, Ullrich A1 - Rochon, Paul A1 - Natansohn, Almeria T1 - Atomic force microscopy inspection of the early state of formation of polymer surface relief grating Y1 - 2001 ER -