@article{43581, abstract = {{The ultrafast dynamics of photoexcited carriers in semiconductor superlattices is studied theoretically on the basis of a Monte Carlo solution of the coupled Boltzmann transport equations for electrons and holes. The approach allows a kinetic description of the relevant interaction mechanisms such as intra- miniband and interminiband carrier-phonon scattering processes. The energy relaxation of photoexcited carriers, as well as their vertical transport, is investigated in detail. The effects of the multiminiband nature of the superlattice spectrum on the energy relaxation process are discussed with particular emphasis on the presence of Bloch oscillations induced by an external electric field. The analysis is performed for different superlattice structures and excitation conditions. It shows the dominant role of carrier–polar-optical-phonon interaction in determining the nature of the carrier dynamics in the low-density limit. In particular, the miniband width, compared to the phonon energy, turns out to be a relevant quantity in predicting the existence of Bloch oscillations.}}, author = {{Meier, Torsten and Rossi, F. and Thomas, P. and Koch, S.W. and Selbmann, P.E. and Molinari, E.}}, journal = {{Physical Review B}}, number = {{23}}, pages = {{16943--16953}}, publisher = {{American Physical Society}}, title = {{{Ultrafast carrier relaxation and vertical-transport phenomena in semiconductor superlattices: A Monte Carlo analysis}}}, doi = {{10.1103/PhysRevB.51.16943}}, volume = {{51}}, year = {{1995}}, } @article{43575, abstract = {{Optical transitions into discrete levels coupled to an optically active continuum lead to asymmetrical Fano lines in the linear absorption spectra, reflecting interference between the excitation channels. We investigate the corresponding four-wave-mixing spectra for the nonlinear optical response within a model of noninteracting electrons. Our results show that four-wave-mixing experiments provide a useful tool to identify Fano resonances.}}, author = {{Meier, Torsten and Schulze, A. and Thomas, P. and Vaupel, H. and Maschke, K.}}, journal = {{Physical Review B}}, number = {{20}}, pages = {{13977--13986}}, publisher = {{American Physical Society}}, title = {{{Signatures of Fano-resonances in four-wave mixing experiments}}}, doi = {{10.1103/PhysRevB.51.13977}}, volume = {{51}}, year = {{1995}}, } @inproceedings{43568, abstract = {{The effective dimensionality of excitons can be drastically changed by applying an alternating electric field. On the basis of a full three-dimensional description of both coherent and incoherent phenomena in anisotropic structures it is found that appropriate applied oscillating fields change the exciton wave function from anisotropic three dimensional to basically two dimensional. This effective-dimension change is caused by dynamic localization which leads to an increase of the exciton binding energy and of the corresponding oscillator strength.}}, author = {{Meier, Torsten and Rossi, F. and Je, K.-C and Hader, J. and Thomas, P. and Koch, S.W.}}, booktitle = {{Proceedings of IV International Conference on Optics of Excitons in Confined Systems}}, location = {{Cortona, Italy}}, pages = {{1693--1697}}, publisher = {{Kluwer Academic Publishers}}, title = {{{Linear and Non-linear Optical Properties of Semiconductor Superlattices: Excitonic and Field-Induced Effects}}}, doi = {{10.1007/BF02457265}}, volume = {{17}}, year = {{1995}}, } @inproceedings{43571, abstract = {{We study exciton ionization induced by an axial electric field in a strongly coupled GaAs/Al0.3 Ga0.7 As superlattice at low temperatures. The field-induced ionization times of the heavy-hole 1s exciton in the miniband field regime are determined from transient four-wave-mixing experiments and theoretical model calculations. They are found to lie between the field ionization times of excitons in bulk semiconductors, and in strongly confined quantum well systems.}}, author = {{Meier, Torsten and von Plessen, G. and Koch, M. and Feldmann, J. and Koch, S.W. and Thomas, P. and Göbel, E.O. and Goosen, K.W. and Kuo, J.M. and Kopf, R.F.}}, booktitle = {{Proceedings of IV International Conference on Optics of Excitons in Confined Systems}}, location = {{Cortona, Italy}}, pages = {{1759--1762}}, title = {{{Electric-Field-Induced Exciton Ionization in a GaAs/AlGaAs Superlattice}}}, doi = {{10.1007/BF02457276}}, volume = {{17}}, year = {{1995}}, } @inproceedings{44278, abstract = {{Transient four-wave mixing (TFWM) has been extensively used during the last few years to study exciton dynamics in semiconductors and in semiconductor heterostructures. These studies have provided significant insight into exciton dynamics in both ordered and disordered systems. There are, nevertheless, still certain aspects of the excitonic TFWM response that are not completely understood. In particular, a complete understanding of the polarization and intensity dependences of the signai strength, the decay of the time-integrated signal, and the temporal characteristics of the time-resolved signal has proven elusive. Recent theoretical and experimental work has indicated that exciton-exciton interactions are important.1·2 Such interactions include incoherent processes, such as excitation-induced dephasing, and the formation of biexcitons. Additionally, some of the phenomena result from disorder, making them sample dependent.}}, author = {{Meier, Torsten and Albrecht, T.F. and Schulze, A. and Koch, M. and Bott, K. and Feldmann, J. and Stolz, W. and Kuhl, J. and Mayer, E.J. and Koch, S.W. and Göbel, E.O. and Cundiff, S.T.}}, booktitle = {{Quantum Electronics and Laser Science Conference}}, isbn = {{1-55752-402-5}}, location = {{Baltimore, Maryland United States}}, publisher = {{Optical Society of America}}, title = {{{Quantum beats from biexcitons in narrow quantum wells: polarization and density dependence}}}, year = {{1995}}, } @inproceedings{44277, abstract = {{The appearance of quantum beats (QBs) between heavy-hole (hh) and light-hole (lh) excitons in GaAs quantum wells (QWs) has been observed in many degenerate-four- wave-mixing (DFWM) experiments with subpicosecond optical pulses. Although the variation of the beat amplitude and phase with polarization of the incident pulses was recognized early on, a consistent theoretical interpretation of exciton coherence for the case of simultaneous excitation of hh and lh excitons is still missing.}}, author = {{Meier, Torsten and Kuhl, J. and Mayer, E.J. and Smith, G.O. and Bott, K. and Heuckeroth, V. and Thomas, P. and Koch, M. and Hey, R. and Ploog, K.}}, booktitle = {{Quantum Electronics and Laser Science Conference}}, isbn = {{1-55752-402-5}}, location = {{Baltimore, Maryland United States}}, publisher = {{Optical Society of America}}, title = {{{Polarization dependence of quantum beats between light-hole and heavy-hole excitons in GaAs quantum wells}}}, year = {{1995}}, } @article{13796, author = {{Santos, Paulo V. and Esser, N. and Groenen, J. and Cardona, M. and Schmidt, Wolf Gero and Bechstedt, F.}}, issn = {{0163-1829}}, journal = {{Physical Review B}}, number = {{24}}, pages = {{17379--17385}}, title = {{{Hydrogen interaction with Sb-terminated GaAs and InP (110) surfaces}}}, doi = {{10.1103/physrevb.52.17379}}, volume = {{52}}, year = {{1995}}, } @article{13798, author = {{Schmidt, Wolf Gero and Bechstedt, F. and Srivastava, G. P.}}, issn = {{0163-1829}}, journal = {{Physical Review B}}, number = {{3}}, pages = {{2001--2007}}, title = {{{III-V(110) surface dynamics from anab initiofrozen-phonon approach}}}, doi = {{10.1103/physrevb.52.2001}}, volume = {{52}}, year = {{1995}}, } @article{13797, author = {{Santos, Paulo V. and Esser, N. and Cardona, M. and Schmidt, Wolf Gero and Bechstedt, F.}}, issn = {{0163-1829}}, journal = {{Physical Review B}}, number = {{16}}, pages = {{12158--12167}}, title = {{{Optical properties of Sb-terminated GaAs and InP (110) surfaces}}}, doi = {{10.1103/physrevb.52.12158}}, volume = {{52}}, year = {{1995}}, } @article{13799, author = {{Schmidt, Wolf Gero and Bechstedt, Friedhelm}}, issn = {{0039-6028}}, journal = {{Surface Science}}, number = {{Part A}}, pages = {{557--563}}, title = {{{Se/GaAs(110): energetics and structure}}}, doi = {{10.1016/0039-6028(95)00317-7}}, volume = {{331-333}}, year = {{1995}}, } @article{13850, author = {{Kress, C. and Fiedler, M. and Schmidt, Wolf Gero and Bechstedt, F.}}, issn = {{0163-1829}}, journal = {{Physical Review B}}, number = {{23}}, pages = {{17697--17700}}, title = {{{Geometrical and electronic structure of the reconstructed diamond (100) surface}}}, doi = {{10.1103/physrevb.50.17697}}, volume = {{50}}, year = {{1995}}, } @article{13800, author = {{Kress, Clemens and Fiedler, Marion and Schmidt, Wolf Gero and Bechstedt, Friedhelm}}, issn = {{0039-6028}}, journal = {{Surface Science}}, pages = {{1152--1156}}, title = {{{Quasi-particle band structure of C(111)2 × 1 and C(100)2 × 1 surfaces}}}, doi = {{10.1016/0039-6028(95)00160-3}}, volume = {{331-333}}, year = {{1995}}, } @article{13851, author = {{Schmidt, Wolf Gero and Bechstedt, F.}}, issn = {{0163-1829}}, journal = {{Physical Review B}}, number = {{23}}, pages = {{17651--17654}}, title = {{{Exchange reactions versus adsorption geometries for Se/GaAs(110)}}}, doi = {{10.1103/physrevb.50.17651}}, volume = {{50}}, year = {{1995}}, } @article{13801, author = {{Schmidt, Wolf Gero and Srivastava, G.P.}}, issn = {{0039-6028}}, journal = {{Surface Science}}, number = {{Part A}}, pages = {{540--545}}, title = {{{III-V(110)/Sb(1 ML): structural and dynamical properties}}}, doi = {{10.1016/0039-6028(95)00304-5}}, volume = {{331-333}}, year = {{1995}}, } @article{13852, author = {{Schmidt, Wolf Gero and Bechstedt, F.}}, issn = {{0163-1829}}, journal = {{Physical Review B}}, number = {{23}}, pages = {{17280--17291}}, title = {{{Se/GaAs(110): Atomic and electronic structure}}}, doi = {{10.1103/physrevb.50.17280}}, volume = {{50}}, year = {{1995}}, } @article{35384, author = {{Kratzat, Krystyna and Schmidt, Claudia and Finkelmann, Heino}}, issn = {{0021-9797}}, journal = {{Journal of Colloid and Interface Science}}, keywords = {{Colloid and Surface Chemistry, Surfaces, Coatings and Films, Biomaterials, Electronic, Optical and Magnetic Materials}}, number = {{1}}, pages = {{190--198}}, publisher = {{Elsevier BV}}, title = {{{A Doubly Branched Nonionic Oligooxyethylene V-Amphiphile: Effect of Molecular Geometry on Liquid-Crystalline Phase Behavior, 3}}}, doi = {{10.1006/jcis.1994.1095}}, volume = {{163}}, year = {{1994}}, } @article{35386, author = {{Grabowski, D. A. and Schmidt, Claudia}}, issn = {{0024-9297}}, journal = {{Macromolecules}}, keywords = {{Materials Chemistry, Inorganic Chemistry, Polymers and Plastics, Organic Chemistry}}, number = {{9}}, pages = {{2632--2634}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Simultaneous Measurement of Shear Viscosity and Director Orientation of a Side-Chain Liquid-Crystalline Polymer by Rheo-NMR}}}, doi = {{10.1021/ma00087a037}}, volume = {{27}}, year = {{1994}}, } @article{35385, author = {{Disch, Stefan and Schmidt, Claudia and Finkelmann, Heino}}, issn = {{1022-1336}}, journal = {{Macromolecular Rapid Communications}}, keywords = {{Materials Chemistry, Polymers and Plastics, Organic Chemistry}}, number = {{4}}, pages = {{303--310}}, publisher = {{Wiley}}, title = {{{Nematic elastomers beyond the critical point}}}, doi = {{10.1002/marc.1994.030150402}}, volume = {{15}}, year = {{1994}}, } @article{35383, author = {{Schnepp, Werner and Schmidt, Claudia}}, issn = {{0005-9021}}, journal = {{Berichte der Bunsengesellschaft für physikalische Chemie}}, keywords = {{General Chemical Engineering}}, number = {{2}}, pages = {{248--252}}, publisher = {{Wiley}}, title = {{{Conformational order of amphiphilic chain molecules in lyotropic liquid-crystalline phases}}}, doi = {{10.1002/bbpc.19940980219}}, volume = {{98}}, year = {{1994}}, } @book{27958, author = {{Bigga, Regine and Braun, F. and Hoffmann, L.}}, title = {{{Die Gleichstellung der Geschlechter im Lehrplan. Anregungen für Schule und Unterricht. }}}, year = {{1994}}, }