@article{HolyStanglZerlauthetal.1999,
  author    = {Hol{\´y}, V{\´a}clav and Stangl, Jochen and Zerlauth, S. and Bauer, G{\"u}nther and Darowski, Nora and L{\"u}bbert, Daniel and Pietsch, Ullrich},
  title     = {Lateral arrangement of self-assembled quantum dots in an SiGe/Si superlattice},
  year      = {1999},
  language  = {en}
}
@article{JoshiPingelGrigorianetal.2009,
  author    = {Joshi, Siddharth and Pingel, Patrick and Grigorian, Souren and Panzner, Tobias and Pietsch, Ullrich and Neher, Dieter and Forster, Michael and Scherf, Ullrich},
  title     = {Bimodal temperature behavior of structure and mobility in high molecular weight p3ht thin films},
  issn      = {0024-9297},
  doi       = {10.1021/Ma900021w},
  year      = {2009},
  abstract  = {We report a temperature dependent crystalline structure of spin-coated thin films of high molecular weight regioregular poly(3-hexylthiophene) (P3HT) (M-n similar to 30000 g/mol) and its correlation with charge carrier mobility. These investigations show a reversible change of the crystalline structure, where the interlayer lattice spacing (100)along the alkyl side chains continuously increases up to a temperature of about 220 degrees C; in contrast, the in-plane pi-pi distance reduces with increasing temperature. These changes in structure are reversible and can be repeated several times. The temperature-induced structural properties differ for thick and thin films, pointing to a surface/interface role in stabilization of the layer morphology. In contrast to the structural changes, the carrier mobility is rather constant in the temperature range from room temperature up to 100-120 degrees C, followed by a continuous decrease. For thick layers this drop is significant and the transistor performance almost vanishes at high temperature, however, it completely recovers upon cooling back to roorn temperature. The drop of the charge carrier mobility at higher temperatures is in contrast with expectations front the structural studies, considering the increase of crystalline fraction of the polycrystalline layer. our electrical measurements Underscore that the reduction of the macroscopic mobility is mostly caused by it pronounced decrease of the intergrain transport. The thermally induced crystallization along(100) direction and the creation of numerous small crystallites at the film-substrate interface reduce the number of long polymer chain, bridging crystalline domains, which ultimately limits the macroscopic charge transport.},
  language  = {en}
}
@article{KarageorgievNeherSchulzetal.2005,
  author    = {Karageorgiev, Peter and Neher, Dieter and Schulz, Burkhard and Stiller, Burkhard and Pietsch, Ullrich and Giersig, Michael and Brehmer, Ludwig},
  title     = {From anisotropic photo-fluidity towards nanomanipulation in the optical near-field},
  issn      = {1476-1122},
  year      = {2005},
  abstract  = {An increase in random molecular vibrations of a solid owing to heating above the melting point leads to a decrease in its long-range order and a loss of structural symmetry. Therefore conventional liquids are isotropic media. Here we report on a light-induced isothermal transition of a polymer film from an isotropic solid to an anisotropic liquid state in which the degree of mechanical anisotropy can be controlled by light. Whereas during irradiation by circular polarized light the film behaves as an isotropic viscoelastic fluid, it shows considerable fluidity only in the direction parallel to the light field vector under linear polarized light. The fluidization phenomenon is related to photoinduced motion of azobenzene-functionalized molecular units, which can be effectively activated only when their transition dipole moments are oriented close to the direction of the light polarization. We also describe here how the photofluidization allows nanoscopic elements of matter to be precisely manipulated},
  language  = {en}
}
@article{KarcenkoEnglischGrenzeretal.2000,
  author    = {Karcenko, Anatolij V. and Englisch, Uwe and Grenzer, J{\"o}rg and Geue, Thomas and Pietsch, Ullrich and Siebrecht, R.},
  title     = {Investigation of partially deuterated multilayers by means of X-ray and polarized neutron reflectometry},
  issn      = {1044-8632},
  year      = {2000},
  language  = {en}
}
@article{LeitenbergerHartmannPietschetal.2008,
  author    = {Leitenberger, Wolfram and Hartmann, Robert and Pietsch, Ullrich and Andritschke, Robert and Starke, Ines and Str{\"u}der, Lothar},
  title     = {Application of a pnCCD in X-ray diffraction : a three-dimensional X-ray detector},
  doi       = {10.1107/S0909049508018931},
  year      = {2008},
  abstract  = {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.},
  language  = {en}
}
@article{LeitenbergerPietsch2007,
  author    = {Leitenberger, Wolfram and Pietsch, Ullrich},
  title     = {A monolithic Fresnel bimirror for hard X-rays and its application for coherence measurements},
  issn      = {0909-0495},
  doi       = {10.1107/S0909049507003846},
  year      = {2007},
  abstract  = {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.},
  language  = {en}
}
@article{LichanotAzavantPietsch1996,
  author    = {Lichanot, Albert and Azavant, P. and Pietsch, Ullrich},
  title     = {Ab-initio Hartree-Fock study of the electronic charge density of the cubic boron nitride and its comparison with the experiment},
  year      = {1996},
  language  = {en}
}
@article{LuebbertBaumbachPontietal.1999,
  author    = {L{\"u}bbert, Daniel and Baumbach, Tilo and Ponti, S. and Pietsch, Ullrich and Leprince, L. and Schneck, J. and Talneau, A.},
  title     = {Strain investigation of low strained buried gratings by grazing incidence X-Ray diffraction and the theory of elasticity},
  year      = {1999},
  language  = {en}
}
@article{MahlerBodensteinPietsch1995,
  author    = {Mahler, Willy and Bodenstein, G. and Pietsch, Ullrich},
  title     = {Phasentransformationen in Cd-Stearat-Multischichten bei unterschiedlichen Metallionenkonzentrationen},
  year      = {1995},
  language  = {de}
}
@article{MetzgerPietschGarstein1999,
  author    = {Metzger, T. H. and Pietsch, Ullrich and Garstein, E.},
  title     = {High-resolution lattice parameter measurement by x-ray grazing incidence diffraction: Application to the interface of silicon on sapphire},
  year      = {1999},
  language  = {en}
}
@article{MukherjeeBhattacharyaSanyaletal.2000,
  author    = {Mukherjee, M. and Bhattacharya, M. K. and Sanyal, M. K. and Geue, Thomas and Grenzer, J{\"o}rg and Pietsch, Ullrich},
  title     = {Temperature dependent thickness and surface tension of polymer films},
  isbn      = {81-7371295-6},
  year      = {2000},
  language  = {en}
}
@article{MukhopadhyayDattaSanyaletal.2001,
  author    = {Mukhopadhyay, M. K. and Datta, A. and Sanyal, M. K. and Geue, Thomas and Pietsch, Ullrich},
  title     = {Synchrotron Studies of Melting of Langmuir-Blodgett Films},
  year      = {2001},
  language  = {en}
}
@article{NeissendorferBolmPietsch1997,
  author    = {Neißendorfer, Frank and Bolm, A. and Pietsch, Ullrich},
  title     = {Energy dispersive X-ray reflectometry and X-ray grazing incidence diffraction from organic multilayers},
  year      = {1997},
  language  = {en}
}
@article{NeissendorferPietschBreszisinskietal.1999,
  author    = {Neißendorfer, Frank and Pietsch, Ullrich and Breszisinski, G. and M{\"o}hwald, Helmuth},
  title     = {Energy-dispersive reflectometry and diffractometry at the WLS of BESSY-I},
  year      = {1999},
  language  = {en}
}
@article{NeumannBuchsteinerMahleretal.2000,
  author    = {Neumann, Werner and Buchsteiner, Alexandra and Mahler, Willy and Geue, Thomas and Pietsch, Ullrich},
  title     = {Dielectric loss spectroscopy at fatty acid salt multilayers},
  year      = {2000},
  abstract  = {Dielectric loss spectroscopy (DLS) was performed at compact samples and lamellary organized Langmuir-Blodgett (LB) films from various fatty acid salts. Previous thermoanalytical measurements at compact samples revealed the appearance of two different phase transition temperatures; the lower one is related to the acid the second one to the acid salt molecules. In spite of ill defined electrical contacts with the film the characteristic DLS frequencies obtained from about 100nm thick multilayer films are similar to those recorded from bulk samples. No significant variations of frequencies were found changing the counter ions. Besides conductivity influence at low frequncies we found two relaxations related to the mobility of the dipolar carboxylat-metal group at about 100 and 10000Hz. One of these frequencies is related to the rotation around the chain axis. The strength of this relaxation increases significantly with increasing the sample temperature above 105°C. This temperature is connected with a structural phase transition observed by X-ray reflectometry. In case of Pb-stearate the results of the dielectric measurements help to interprete this structural change as a transition from an orthorhombic into a free-rotator phase. The uncorrelated rotation of molecules around their molecular axes initiates a much increased relaxation strength at the carboxylat-metal sites.},
  language  = {en}
}
@article{PanznerGleberSantetal.2007,
  author    = {Panzner, Tobias and Gleber, Gudrun and Sant, Tushar and Leitenberger, Wolfram and Pietsch, Ullrich},
  title     = {Coherence experiments at the white-beam beamline of BESSYI},
  doi       = {10.1016/j.tsf.2006.12.002},
  year      = {2007},
  abstract  = {The third-generation X-ray source BESSYII (Berlin, Germany) provides coherent X-ray radiation which can be used for static and dynamic speckle analysis. Recently we have demonstrated that one can perform experiments with coherent white radiation provided by a bending magnet (5 < E < 20 keV). In this paper we show that the diffraction figure of the initial pinhole must be considered for the interpretation of coherent experiments. The reflectivity spectrum of a sample results from the Fresnel diffraction of the incident pinhole deformed by the static speckle features of the sample surface. For dynamical experiments all speckle like features alter with time whereas the pure Fresnel fringes remain constant. (c) 2007 Published by Elsevier B.V.},
  language  = {en}
}
@article{PaschkeGeueBarberkaetal.1997,
  author    = {Paschke, K. and Geue, Thomas and Barberka, Thomas Andreas and Bolm, A. and Pietsch, Ullrich and R{\"o}sch, M. and Batke, Edwin and Faller, F. and Kerkel, K. and Oshiniwo, J. and Forchel, Alfred},
  title     = {Characterization of lateral semiconductor nano structures by means of x-ray grazing-incidence diffraction},
  year      = {1997},
  language  = {en}
}
@article{Pietsch2003,
  author    = {Pietsch, Ullrich},
  title     = {Evidence of a density grating under light induced formation of surface relief gratings at polymers containing azobenzene moieties},
  year      = {2003},
  language  = {en}
}
@article{Pietsch2003,
  author    = {Pietsch, Ullrich},
  title     = {Thin Layers of columns of an amphiphilic hexa-peri-hexabenzocoronene at silicon wafer surfaces},
  year      = {2003},
  language  = {en}
}
@article{Pietsch2002,
  author    = {Pietsch, Ullrich},
  title     = {X-ray reflectivity from sinusoidal surface relief gratings},
  year      = {2002},
  language  = {en}
}