@article{40326, author = {{Baena, Maria J. and Buey, Julio and Espinet, Pablo and Kitzerow, Heinz-Siegfried and Heppke, Gerd}}, issn = {{0570-0833}}, journal = {{Angewandte Chemie International Edition in English}}, keywords = {{General Chemistry, Catalysis}}, number = {{8}}, pages = {{1201--1203}}, publisher = {{Wiley}}, title = {{{Metallomesogens with a Cholesteric Mesophase}}}, doi = {{10.1002/anie.199312011}}, volume = {{32}}, year = {{1993}}, } @article{43449, abstract = {{We present subpicosecond time-resolved four-wave-mixing studies on GaAs/AlAs short-period superlattices having different miniband widths. Photon echoes are observed as a consequence of the inhomogeneous broadening of the excitonic resonance. In addition, the photon-echo signal exhibits periodic modulations as a function of the time delay between the excitation laser pulses. Free excitons and excitons bound to neutral acceptors are identified as the underlying three-level system leading to the observed photon-echo quantum beats. From the beat period we can directly infer the dissociation energy of the bound exciton. In accordance with theory, we find that the dissociation energy decreases with increasing miniband width, i.e., when the excitons become less confined. In addition, we find that the dephasing rate of bound excitons is about one order of magnitude less than that of free excitons and is mainly determined by energy relaxation.}}, author = {{Meier, Torsten and Koch, M. and Weber, D. and Feldmann, J. and Göbel, E.O. and Schulze, A. and Thomas, P. and Schmitt-Rink, S. and Ploog, K.}}, journal = {{Physical Review B}}, number = {{3}}, pages = {{1532--1539}}, publisher = {{American Physical Society}}, title = {{{Subpicosecond photon-echo spectroscopy on GaAs/AlAs short-period superlattices}}}, doi = {{10.1103/PhysRevB.47.1532}}, volume = {{47}}, year = {{1993}}, } @inbook{43442, abstract = {{Femtosecond nonlinear laser spectroscopy is applied to study the dynamics of coherent optical excitations in semiconductors. In particular, beat phenomena of excitonic excitations in quantum wells and superlattice structures will be considered. We will demonstrate that four wave mixing experiments with time resolved detection of the nonlinear signal are able to distinguish between quantum beats and polarization interference. In addition, we report for a GaAs/AlAs superlattice the observation of quantum beats in the photon echo signal. The occurence of these beats is attributed to the simultaneous excitation of bound and localized excitons.}}, author = {{Meier, Torsten and Göbel, E.O. and Koch, M. and Feldmann, J. and von Plessen, G. and Schulze, A. and Thomas, P. and Schmitt-Rink, S. and Köhler, K. and Ploog, K.}}, booktitle = {{Optical Phenomena in Semiconductor Structures of Reduced Dimension}}, editor = {{Lookwood, D. and Pinczuk, A.}}, isbn = {{978-94-010-4845-3}}, pages = {{145--155}}, publisher = {{Springer}}, title = {{{Time resolved Four Wave Mixing in GaAs/AlAs Quantum Well Structures}}}, doi = {{10.1007/978-94-011-1912-2_14}}, year = {{1993}}, } @article{43448, abstract = {{We report on the coherent dynamics of excitonic wave packets observed in transient four-wave mixing experiments on strained InGaAs/GaAs quantum-well structures. The excitonic noneigenstates are created by using laser pulses shorter than the electron round trip time within the exciton orbital. A characteristic temporal modulation of the diffracted signal is observed, which resembles the coherent dynamics of an electron wave packet in a hydrogen atom expected for the case of a simultaneous excitation of all bound and the lowest continuum states.}}, author = {{Meier, Torsten and Feldmann, J. and von Plessen, G. and Koch, M. and Göbel, E.O. and Thomas, P. and Bacher, G. and Hartmann, C. and Schweizer, H. and Schäfer, W. and Nickel, H.}}, journal = {{Physical review letters}}, number = {{20}}, pages = {{3027--3030}}, publisher = {{American Physical Society}}, title = {{{Coherent Dynamics of Excitonic Wave Packets}}}, doi = {{10.1103/PhysRevLett.70.3027}}, volume = {{70}}, year = {{1993}}, } @article{43447, abstract = {{Exciton coupling is studied for double quantum wells, which are separated by thick barriers. Results are presented for the linear optical spectrum, stationary and transient luminescence as well as four-wave-mixing signals. Additionally, coherent and incoherent transport through the barrier is considered}}, author = {{Meier, Torsten and Batsch, M. and Thomas, P. and Lindberg, M. and Koch, S.W. and Shah, J.}}, journal = {{Physical Review B}}, number = {{16}}, pages = {{11817--11826}}, publisher = {{American Physical Society}}, title = {{{Dipole-dipole coupling of excitons in double quantum wells}}}, doi = {{10.1103/PhysRevB.48.11817}}, volume = {{48}}, year = {{1993}}, } @inproceedings{44286, abstract = {{In degenerate four-wave-mixing (DFWM) experiments the polarization of the incident laser pulses can have a strong influence on the measured signal. For GaAs quantum wells a number of DFWM experiments were performed by using either parallel or perpendicular polarization of the incident laser pulses. Experimentally, it turned out that some characteristic features of the signal differ appreciably for the two configurations. In particular, different dephasing times, phase shifts of the quantum beats, different time-resolved behavior (echoes versus free-induction decay), and intensity dependence of the measured signal have been reported}}, author = {{Meier, Torsten and Bennhardt, D. and Thomas, P. and Eccleston, R. and Mayer, E. and Kuhl, J.}}, booktitle = {{Quantum Electronics and Laser Science Conference}}, isbn = {{1-55752-302-9}}, location = {{Baltimore, Maryland United States}}, title = {{{Theory for polarization-dependent four-wave-mixing signals in quantum wells}}}, year = {{1993}}, } @inproceedings{44287, abstract = {{We investigate the coherent coupling of free and bound excitonic transitions, as wets as of distinct excitonic transitions arising from spatially separated quantum-well islands by means of time-resolved four-wave-mixing experiments.}}, author = {{Meier, Torsten and Koch, M. and Feldmann, J. and von Plessen, G. and Schulze, A. and Göbel, E.O. and Thomas, P. and Schmitt-Rink, S. and Shah, J. and Ploog, K. and Köhler, K.}}, booktitle = {{Quantum Electronics and Laser Science Conference}}, isbn = {{1-55752-302-9}}, location = {{Baltimore, Maryland United States}}, title = {{{Coherent coupling of exciton transitions in semiconductor quantum structures}}}, year = {{1993}}, } @article{13858, author = {{Schmidt, Wolf Gero and Wenzien, Bernd and Bechstedt, Friedhelm}}, issn = {{0011-4626}}, journal = {{Czechoslovak Journal of Physics}}, number = {{9-10}}, pages = {{1003--1007}}, title = {{{AB initio calculation of the atomic and electronic structure for Sb adsorbed on GaAs(110)}}}, doi = {{10.1007/bf01595293}}, volume = {{43}}, year = {{1993}}, } @article{13857, author = {{Schmidt, Wolf Gero and Srivastava, G P}}, issn = {{0953-8984}}, journal = {{Journal of Physics: Condensed Matter}}, number = {{49}}, pages = {{9025--9036}}, title = {{{Chemisorption of aluminium on GaAs(110)}}}, doi = {{10.1088/0953-8984/5/49/005}}, volume = {{5}}, year = {{1993}}, } @article{37467, author = {{Bigga, Regine}}, journal = {{Lehrplanrevision in Schleswig-Holstein}}, location = {{Kiel}}, pages = {{69 -- 78}}, publisher = {{Kultusministerium Schleswig-Holstein}}, title = {{{Forschungsergebnisse zur Geschlechterfrage - Konsequenzen für die Gestaltung von Unterricht sowie für die Aus- und Weiterbildung von Lehrkräften}}}, year = {{1992}}, } @article{40009, author = {{Kitzerow, Heinz-Siegfried and Crooker, P. P. and Heppke, G.}}, issn = {{0267-8292}}, journal = {{Liquid Crystals}}, keywords = {{Condensed Matter Physics, General Materials Science, General Chemistry}}, number = {{1}}, pages = {{49--58}}, publisher = {{Informa UK Limited}}, title = {{{Chromaticity of polymer-dispersed cholesteric liquid crystals}}}, doi = {{10.1080/02678299208029037}}, volume = {{12}}, year = {{1992}}, } @article{40013, author = {{Kitzerow, Heinz-Siegfried and Crooker, P. P.}}, issn = {{0267-8292}}, journal = {{Liquid Crystals}}, keywords = {{Condensed Matter Physics, General Materials Science, General Chemistry}}, number = {{4}}, pages = {{561--568}}, publisher = {{Informa UK Limited}}, title = {{{Behaviour of polymer dispersed cholesteric droplets with negative dielectric anisotropy in electric fields}}}, doi = {{10.1080/02678299208029010}}, volume = {{11}}, year = {{1992}}, } @article{40008, author = {{Kitzerow, Heinz-Siegfried and Xu, F. and Crooker, P. P.}}, issn = {{0267-8292}}, journal = {{Liquid Crystals}}, keywords = {{Condensed Matter Physics, General Materials Science, General Chemistry}}, number = {{6}}, pages = {{1019--1024}}, publisher = {{Informa UK Limited}}, title = {{{Microscopic observations of axial and radial nematic droplets for a dual-frequency addressable liquid crystal}}}, doi = {{10.1080/02678299208032817}}, volume = {{12}}, year = {{1992}}, } @article{40075, author = {{Kitzerow, Heinz-Siegfried and Crooker, P. P. and Rand, J. and Xu, J. and Heppke, G.}}, issn = {{1155-4312}}, journal = {{Journal de Physique II}}, keywords = {{Physics and Astronomy (miscellaneous), General Engineering, Atomic and Molecular Physics, and Optics}}, number = {{3}}, pages = {{279--284}}, publisher = {{EDP Sciences}}, title = {{{Electrostriction dynamics of blue phase II crystallites}}}, doi = {{10.1051/jp2:1992132}}, volume = {{2}}, year = {{1992}}, } @article{40077, author = {{Dolganov, V. K. and Heppke, G. and Kitzerow, Heinz-Siegfried}}, issn = {{1155-4312}}, journal = {{Journal de Physique II}}, keywords = {{Physics and Astronomy (miscellaneous), General Engineering, Atomic and Molecular Physics, and Optics}}, number = {{10}}, pages = {{1803--1809}}, publisher = {{EDP Sciences}}, title = {{{Dynamic response of a blue phase to an applied field}}}, doi = {{10.1051/jp2:1992236}}, volume = {{2}}, year = {{1992}}, } @article{40078, author = {{Kitzerow, Heinz-Siegfried and Rand, J. and Crooker, P. P.}}, issn = {{1155-4312}}, journal = {{Journal de Physique II}}, keywords = {{Physics and Astronomy (miscellaneous), General Engineering, Atomic and Molecular Physics, and Optics}}, number = {{2}}, pages = {{227--234}}, publisher = {{EDP Sciences}}, title = {{{Dynamics of polymer-dispersed cholesteric liquid crystals}}}, doi = {{10.1051/jp2:1992126}}, volume = {{2}}, year = {{1992}}, } @article{40331, author = {{Xu, F. and Kitzerow, Heinz-Siegfried and Crooker, P. P.}}, issn = {{1050-2947}}, journal = {{Physical Review A}}, keywords = {{Atomic and Molecular Physics, and Optics}}, number = {{10}}, pages = {{6535--6540}}, publisher = {{American Physical Society (APS)}}, title = {{{Electric-field effects on nematic droplets with negative dielectric anisotropy}}}, doi = {{10.1103/physreva.46.6535}}, volume = {{46}}, year = {{1992}}, } @article{40329, author = {{Kitzerow, Heinz-Siegfried and Molsen, Henning and Heppke, Gerd}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, keywords = {{Physics and Astronomy (miscellaneous)}}, number = {{25}}, pages = {{3093--3095}}, publisher = {{AIP Publishing}}, title = {{{Linear electro‐optic effects in polymer‐dispersed ferroelectric liquid crystals}}}, doi = {{10.1063/1.106762}}, volume = {{60}}, year = {{1992}}, } @article{40330, author = {{Kitzerow, Heinz-Siegfried and Molsen, Henning and Heppke, Gerd}}, issn = {{1042-7147}}, journal = {{Polymers for Advanced Technologies}}, keywords = {{Polymers and Plastics}}, number = {{5}}, pages = {{231--235}}, publisher = {{Wiley}}, title = {{{Helical unwinding in polymer-dispersed ferroelectric liquid crystals}}}, doi = {{10.1002/pat.1992.220030506}}, volume = {{3}}, year = {{1992}}, } @article{40328, abstract = {{ We investigated the switching behavior of the well-known antiferroelectric liquid crystal (R)-4-(1-methylheptyloxycarbonyl)phenyl-4'-octyloxybiphenyl-4-carboxylate (MHPOBC), embedded in a polymer matrix. The alignment of the liquid crystal in the UV-cured adhesive was controlled by mechanical shear during the polymerization-induced phase separation. Multistable switching with time constants down to 150 µs indicates that antiferroelectric PDLC devices are promissing for electrooptic application as flexible displays. }}, author = {{Molsen, Henning and Kitzerow, Heinz-Siegfried and Heppke, Gerd }}, issn = {{0021-4922}}, journal = {{Japanese Journal of Applied Physics}}, keywords = {{General Physics and Astronomy, General Engineering}}, number = {{8A}}, publisher = {{IOP Publishing}}, title = {{{Antiferroelectric Switching in Polymer-Dispersed Liquid Crystals}}}, doi = {{10.1143/jjap.31.l1083}}, volume = {{31}}, year = {{1992}}, }