@article{StoemmerMartinGeueetal.1998, author = {St{\"o}mmer, Ralph and Martin, C. R. and Geue, Thomas and G{\"o}bel, H. and Hub, W. and Pietsch, Ullrich}, title = {Comparative studies of fractal parameters of Si(100) surfaces measured by X-ray scattering and atomic force microscopy}, year = {1998}, language = {en} } @article{StumpeGeueFischeretal.1995, author = {Stumpe, Joachim and Geue, Thomas and Fischer, Thomas M. and Menzel, Henning}, title = {Photochemically induced changes of structures in LB-multilayers of amphotropic polymers}, year = {1995}, language = {en} } @article{StillerKarageorgievGeueetal.2004, author = {Stiller, Burkhard and Karageorgiev, Peter and Geue, Thomas and Morawetz, Knut and Saphiannikova, Marina and Mechau, Norman and Neher, Dieter}, title = {Optically induced mass transport studied by scanning near-field optical- and atomic force microscopy}, issn = {0204-3467}, year = {2004}, abstract = {Some functionalised thin organic films show a very unusual property, namely the light induced material transport. This effect enables to generate three-dimensional structures on surfaces of azobenzene containing films only caused by special optical excitation. The physical mechanisms underlying this phenomenon have not yet been fully understood, and in addition, the dimensions of structures created in that way are macroscopic because of the optical techniques and the wavelength of the used light. In order to gain deeper insight into the physical fundamentals of this phenomenon and to open possibilities for applications it is necessary to create and study structures not only in a macroscopic but also in nanometer range. We first report about experiments to generate optically induced nano structures even down to 100 nm size. The optical stimulation was therefore made by a Scanning Near-field Optical Microscope (SNOM). Secondly, physical conditions inside optically generated surface relief gratings were studied by measuring mechanical properties with high lateral resolution via pulse force mode and force distance curves of an AFM}, language = {en} } @article{StillerKarageorgievBuchsteineretal.2003, author = {Stiller, Burkhard and Karageorgiev, Peter and Buchsteiner, Andrea and Geue, Thomas and Henneberg, Oliver and Brehmer, Ludwig and Natansohn, Almeria and Hollricher, Olga}, title = {Using light as a tool : optically Induced mass transport generated in Near-Fields}, issn = {0038-7355 -}, year = {2003}, language = {en} } @article{StillerGeueMorawetzetal.2005, author = {Stiller, Burkhard and Geue, Thomas and Morawetz, Knut and Saphiannikova, Marina}, title = {Optical patterning in azobenzene polymer films}, issn = {0022-2720}, year = {2005}, abstract = {Thin azobenzene polymer films show a very unusual property, namely optically induced material transport. The underlying physics for this phenomenon has not yet been thoroughly explained. Nevertheless, this effect enables one to inscribe different patterns onto film surfaces, including one- and two-dimensional periodic structures. Typical sizes of such structures are of the order of micrometers, i.e. related to the interference pattern made by the laser used for optical excitation. In this study we have measured the mechanical properties of one- and two-dimensional gratings, with a high lateral resolution, using force-distance curves and pulse force mode of the atomic force microscope. We also report on the generation of considerably finer structures, with a typical size of 100 nm, which were inscribed onto the polymer surface by the tip of a scanning near-field optical microscope used as an optical pen. Such inscription not only opens new application possibilities but also gives deeper insight into the fundamentals physics underlying optically induced material transport}, language = {en} } @article{StahnPucherGeueetal.1998, author = {Stahn, Jochen and Pucher, Andreas and Geue, Thomas and Daniel, A. and Pietsch, Ullrich}, title = {Electric field induced electron density response of GaAs and ZnSe}, year = {1998}, language = {en} } @article{StahnGeueGrenzeretal.2000, author = {Stahn, Jochen and Geue, Thomas and Grenzer, J{\"o}rg and Pietsch, Ullrich}, title = {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}, year = {2000}, language = {en} } @article{SaphiannikovaGeueHennebergetal.2004, author = {Saphiannikova, Marina and Geue, Thomas and Henneberg, Oliver and Morawetz, Knut and Pietsch, Ullrich}, title = {Linear viscoelastic analysis of formation and relaxation of azobenzene polymer gratings}, doi = {10.1063/1.1642606}, year = {2004}, abstract = {Surface relief gratings on azobenzene containing polymer films were prepared under irradiation by actinic light. Finite element modeling of the inscription process was carried out using linear viscoelastic analysis. It was assumed that under illumination the polymer film undergoes considerable plastification, which reduces its original Young's modulus by at least three orders of magnitude. Force densities of about 10(11) N/m(3) were necessary to reproduce the growth of the surface relief grating. It was shown that at large deformations the force of surface tension becomes comparable to the inscription force and therefore plays an essential role in the retardation of the inscription process. In addition to surface profiling the gradual development of an accompanying density grating was predicted for the regime of continuous exposure. Surface grating development under pulselike exposure cannot be explained in the frame of an incompressible fluid model. However, it was easily reproduced using the viscoelastic model with finite compressibility. (C) 2004 American Institute of Physics}, language = {en} } @article{ReinholdGeueHuberetal.2009, author = {Reinhold, Beate and Geue, Thomas and Huber, Patrick and Sant, Tushar and Pietsch, Ullrich and Sztucki, Michael}, title = {In situ and ex situ SAXS investigation of colloidal sedimentation onto laterally patterned support}, issn = {0743-7463}, doi = {10.1021/La803078b}, year = {2009}, abstract = {We report on in situ investigations of colloidal ordering during gravity sedimentation from a colloidal suspension onto a prepatterned support using a polymeric surface relief grating (SRG) as the support. The ordering of colloids with a diameter of 420 nm was investigated by means of grazing-incidence small-angle X-ray scattering (GISAXS) and transmission SAXS using a preparation cell guaranteeing stable temperature and humidity. GISAXS was used for in situ monitoring of the time evolution of colloidal ordering within the whole illuminated sample area. The onset of ordering was indicated by the increase of integrated intensity within a small time frame shortly before complete evaporation of the dispersant. Single domains of coated samples were investigated ex situ by SAXS in transmission geometry where the irradiated sample area was 200 x 200 mu m(2) only. Domains with the typical size of a few millimeters were observed varying in orientation and crystallographic structure for various positions at the sample. They were mainly oriented along the grooves of the grating, confirming the influence of the underlying grating on colloidal ordering.}, language = {en} } @article{ReichePenacoradaGeueetal.1995, author = {Reiche, J{\"u}rgen and Penacorada, Florencio and Geue, Thomas and Pietsch, Ullrich and Brehmer, Ludwig}, title = {In-plane structure of uranylarachidate multilayers}, year = {1995}, language = {en} }