TY - JOUR A1 - Saphiannikova, Marina A1 - Henneberg, Oliver A1 - Gene, T. M. A1 - Pietsch, Ullrich A1 - Rochon, Paul T1 - Nonlinear effects during inscription of azobenzene surface relief gratings N2 - Surface relief gratings were inscribed on azobenzene polymer films using a pulselike exposure of an Ar+ laser. The inscription process was initiated by a sequence of short pulses followed by much longer relaxation pauses. The development of the surface relief grating was probed by a He-Ne laser measuring the scattering intensity of the first- order grating peak. The growth time of the surface relief grating was found to be larger than the length of the pulses used. This unusual behavior can be considered as a nonlinear material response associated with the trans-cis isomerization of azobenzene moieties. In this study the polymer stress was assumed to be proportional to the number of cis-isomers. One-dimensional viscoelastic analysis was used to derive the polymer deformation. The rate of trans-cis isomerization increases with the intensity of the inscribing light; in the dark it is equal to the rate of thermal cis- trans isomerization. The respective relaxation times were estimated by fitting theoretical deformation curves to experimental data Y1 - 2004 SN - 1520-6106 ER - TY - JOUR A1 - Send, Sebastian A1 - Abboud, Ali A1 - Hartmann, Robert A1 - Huth, M. A1 - Leitenberger, Wolfram A1 - Pashniak, N. A1 - Schmidt, J. A1 - Strüder, Lothar A1 - Pietsch, Ullrich T1 - Characterization of a pnCCD for applications with synchrotron radiation JF - Nuclear instruments & methods in physics research : a journal on accelerators, instrumentation and techniques applied to research in nuclear and atomic physics, materials science and related fields in physics ; A, Accelerators, spectrometers, detectors and associated equipment N2 - In this work we study the response of a pnCCD by means of X-ray spectroscopy in the energy range between 6 key and 20 key and by Laue diffraction techniques. The analyses include measurements of characteristic detector parameters like energy resolution, count rate capability and effects of different gain settings. The limit of a single photon counting operation in white beam X-ray diffraction experiments is discussed with regard to the occurrence of pile-up events, for which the energy information about individual photons is lost. In case of monochromatic illumination the pnCCD can be used as a fast conventional CCD with a charge handling capacity (CHC) of about 300,000 electrons per pixel. If the CHC is exceeded, any surplus charge will spill to neighboring pixels perpendicular to the transfer direction due to electrostatic repulsion. The possibilities of increasing the number of storable electrons are investigated for different voltage settings by exposing a single pixel with X-rays generated by a microfocus X-ray source. The pixel binning mode is tested as an alternative approach that enables a pnCCD operation with significantly shorter readout times. KW - pnCCD KW - X-ray spectroscopy KW - X-ray imaging KW - Energy-dispersive Laue diffraction Y1 - 2013 U6 - https://doi.org/10.1016/j.nima.2013.01.044 SN - 0168-9002 VL - 711 IS - 5 SP - 132 EP - 142 PB - Elsevier CY - Amsterdam 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 - Send, Sebastian A1 - von Kozierowski, Marc A1 - Panzner, Tobias A1 - Gorfman, Semen A1 - Nurdan, Kivanc A1 - Walenta, Albert H. A1 - Pietsch, Ullrich A1 - Leitenberger, Wolfram A1 - Hartmann, Robert A1 - Strüder, Lothar T1 - Energy-dispersive Laue diffraction by means of a frame-store pnCCD Y1 - 2009 UR - http://journals.iucr.org/j/journalhomepage.html U6 - https://doi.org/10.1107/S0021889809039867 SN - 0021-8898 ER - TY - JOUR A1 - Siebrecht, R. A1 - Schreyer, A. A1 - Englisch, Uwe A1 - Pietsch, Ullrich A1 - Zabel, Hartmut T1 - The new reflectometer ADAM at the ILL Y1 - 1997 ER - TY - JOUR A1 - Stahn, Jochen A1 - Geue, Thomas A1 - Grenzer, Jörg A1 - Pietsch, Ullrich T1 - Interaction of short-chain alkanes with surface and interfaces of multilayer films built from amphiphilic molecules: an in-situ X-ray and neutron scattering probe Y1 - 2000 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 - Stahn, Jochen A1 - Möhle, Marcus A1 - Pietsch, Ullrich T1 - Comparison of theoretical and experimental structure amplitudes of GaAs Y1 - 1998 ER - TY - JOUR A1 - Stahn, Jochen A1 - Pietsch, Ullrich A1 - Blaha, Pawel A1 - Schwarz, K. H. T1 - Electric field induced charge-density variations in covalently bonded compounds Y1 - 2001 ER - TY - JOUR A1 - Stahn, Jochen A1 - Pucher, Andreas A1 - Geue, Thomas A1 - Daniel, A. A1 - Pietsch, Ullrich T1 - Electric field induced electron density response of GaAs and ZnSe Y1 - 1998 ER -