TY - CHAP A1 - Schreiber, Michael A1 - Hartmann, Michael T1 - Numerical Study of the Photoexcitation of Solitons in Conjugated Polymers T2 - 3rd International conference on excitonic processes in condensed matter (EXCON '98) N2 - Keine Angabe - No details KW - Excitonic processes KW - Condensed matter KW - EXCON Y1 - 1998 N1 - Online: http://books.google.de/books?id=eRhkFFqeWDUC&pg=PA71&lpg=PA71&dq=Numerical+Study+of+the+Photoexcitation+of+Solitons+in+Conjugated+Polymers&source=bl&ots=qUrItz2xA5&sig=M_kSx03VP1h1OOe_KGkel8BJnB4&hl=de&sa=X&ei=q2K1U_CBAqf54QSAlYCgDA&ved=0CC8Q6AEwAQ#v=onepage&q=Numerical%20Study%20of%20the%20Photoexcitation%20of%20Solitons%20in%20Conjugated%20Polymers&f=false ER - TY - JOUR A1 - Hartmann, Michael A1 - Schreiber, Michael A1 - Streitwolf, H.-W. A1 - Mukamel, Shaul T1 - Nonlinear optical excitations in femtosecond spectroscopy of conjugated polymers JF - Journal of Luminescence N2 - We have investigated the optical excitation of solitons and charge transfer excitons in polymer chains by solving the equations of motion for the reduced density matrix and the lattice displacement simultaneously in time. Electron-phonon coupling leads to polaron-exciton formation which can be identified in transient pump-probe signals. KW - Optical excitation KW - Femtosecond spectroscopy KW - Conjugated polymers Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5795 VL - 66-67 SP - 97 EP - 101 ER - TY - CHAP A1 - Hartmann, Michael A1 - Takahashi, Akira A1 - Mukamel, Shaul A1 - Schreiber, Michael T1 - Soliton and exciton effects in femtosecond spectroscopy of conjugated polymers T2 - International Conference on Excitonic Processes in Condensed Matter N2 - We introduce a concept which allows to study the nonlinear optical response of conjugated polymers taking into account many-body effects of the excitation process. The formation of charge transfer excitons and the creation of lattice distortions are studied in short polymer chains by solving the self consistent equations of motion for the reduced single electron density matrix and the lattice displacement. The coupling of electronic motions to lattice dynamics gives rise to the formation of excitonic polarons, which can be identified in the femtosecond pump-probe signal. KW - Engineering KW - Polymers KW - Spectroscopy Y1 - 1995 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER - TY - JOUR A1 - Glasberg, Ronald A1 - Hartmann, Michael A1 - Draheim, Michael A1 - Tamm, Gerrit A1 - Hessel, Franz T1 - Risks and Crises for Healthcare Providers: the Impact of Cloud Computing JF - The Scientific World Journal N2 - We analyze risks and crises for healthcare providers and discuss the impact of cloud computing in such scenarios. The analysis is conducted in a holistic way, taking into account organizational and human aspects, clinical, IT-related, and utilities-related risks as well as incorporating the view of the overall risk management. KW - Healthcare KW - Cloud Computing Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-9695 ER - TY - JOUR A1 - Schermuly, Carsten C. A1 - Draheim, Michael A1 - Glasberg, Ronald A1 - Stantchev, Vladimir A1 - Tamm, Gerrit A1 - Hartmann, Michael A1 - Hessel, Franz T1 - Human resource crises in German hospitals: an explorative study JF - Human Resources for Health N2 - The complexity of providing medical care in a high-tech environment with a highly specialized, limited labour force makes hospitals more crisis-prone than other industries. An effective defence against crises is only possible if the organizational resilience and the capacity to handle crises become part of the hospitals’ organizational culture. To become more resilient to crises, a raised awareness — especially in the area of human resource (HR) — is necessary. The aim of this paper is to contribute to the process robustness against crises through the identification and evaluation of relevant HR crises and their causations in hospitals. Qualitative and quantitative methods were combined to identify and evaluate crises in hospitals in the HR sector. A structured workshop with experts was conducted to identify HR crises and their descriptions, as well as causes and consequences for patients and hospitals. To evaluate the findings, an online survey was carried out to rate the occurrence (past, future) and dangerousness of each crisis. Six HR crises were identified in this study: staff shortages, acute loss of personnel following a pandemic, damage to reputation, insufficient communication during restructuring, bullying, and misuse of drugs. The highest occurrence probability in the future was seen in staff shortages, followed by acute loss of personnel following a pandemic. Staff shortages, damage to reputation, and acute loss of personnel following a pandemic were seen as the most dangerous crises. The study concludes that coping with HR crises in hospitals is existential for hospitals and requires increased awareness. The six HR crises identified occurred regularly in German hospitals in the past, and their occurrence probability for the future was rated as high. KW - Crises Management KW - Hospital Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-7288 VL - 40 IS - 13 ER - TY - CHAP A1 - Hartmann, Michael A1 - Takahashi, Akira A1 - Mukamel, Shaul A1 - Schreiber, Michael T1 - Soliton and Exciton Effects in Femtosecond Pump Probe Spectroscopy of Conjugated Polymers T2 - International Conference on Excitonic Processes in Condensed Matter, Darwin N2 - Keine Angabe - No details KW - Engineering KW - Femtosecond pump probe KW - Conjugated polymers Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5859 ER - TY - JOUR A1 - Schermuly, Carsten C. A1 - Draheim, Michael A1 - Flessa, Steffen A1 - Glasberg, Ronald A1 - Stantchev, Vladimir A1 - Tamm, Gerrit A1 - Hartmann, Michael A1 - Hessel, Franz T1 - Management of Crises and Risks in German Hospitals: Factors Influencing Medication Errors JF - Value in Health N2 - In German hospitals there is a need for optimized crisis- and risk management. About one third of all hospital-acquired patient damages are due to medication errors. The aim of our interdisciplinary project “Risk Management in Hospitals” is to analyze the behavior of the various key players in the fields of medical care, human resources, supply and IT-systems in the context of various simulated risk scenarios as well as to develop adequate risk management tools. In this abstract, the first Results on medication errors are presented. KW - Health Management KW - Crisis Management KW - Risk Management KW - Medication Errors Y1 - 2014 N1 - Online: https://www.researchgate.net/publication/280259250_PHP133_Management_of_Crises_and_Risks_in_German_Hospitals_-_Factors_Influencing_Medication_Errors VL - 17 IS - 7 SP - A426 ER - TY - CHAP A1 - Bonačić-Koutecký, Vlasta A1 - Hartmann, Michael A1 - Pittner, Jiřı́ A1 - Dam, Huub van ED - Barone, Vincenzo ED - Bencini, Alessandro ED - Fantucci, Piercarlo T1 - Theoretical exploration of single and multi state femtosecond nuclear dynamics of small metallic clusters using the DF method T2 - Recent Advances in Density Functional Methods: Part 3 N2 - Keine Angabe - No details KW - Nuclear dynamics KW - Metallic clusters KW - DF method Y1 - 2000 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. SP - Keine Angabe - No details EP - Keine Angabe - No details PB - World Scientific CY - Singapore ER - TY - JOUR A1 - Andrianov, Igor A1 - Bonačić-Koutecký, Vlasta A1 - Hartmann, Michael A1 - Manz, Jörn A1 - Pittner, Jiřı́ A1 - Sundermann, K. T1 - Ab initio three-dimensional quantum dynamics of Ag3 clusters in the NeNePo process JF - Chemical Physics Letters N2 - The first three-dimensional quantum-dynamical ab initio simulation of the large amplitude vibrational dynamics of an Ag3 cluster initiated from its linear transition state is presented. This can be monitored by femtosecond pump-probe negative-ion to neutral-to-positive-ion spectroscopy with zero electron kinetic energy (NeNePo-ZEKE). The time evolution of the representative wavepacket confirms the dynamical effects which have been discovered previously by Wigner-type semiclassical simulations: the initial coherent bending and stretching from linear to near equilateral triangular configuration, followed by intracluster collision and intracluster vibrational relaxation with a weak fractional revival. In addition, the quantum wavepacket shows interferences and spreading. KW - Chemical physics KW - Three dimensional quantum dynamics Y1 - 2000 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5637 VL - 318 IS - 1-3 SP - 256 EP - 262 ER - TY - JOUR A1 - Hartmann, Michael A1 - Pittner, Jiřı́ A1 - Dam, Huub van A1 - Bonačić-Koutecký, Vlasta T1 - Theoretical study of femtosecond pump–probe signals of nonstoichiometric alkali halide clusters JF - The European Physical Journal D N2 - We present the outline of the ab–initio molecular dynamics method for adiabatic excited states which is suitable to treat the involved excited electronic states simultaneously with the motion of the nuclei. The method allows the simulation of time–resolved pump–probe signals and the analysis of the signals in terms of the underlying nuclear dynamics. Moreover, the timescales of the structural relaxation in excited electronic states vs. intramolecular vibrational relaxation processes can be estimated and the influence of the initial temperature of the cluster can be determined. The method is applied to the analysis of the timescales as well as of the dynamics of localized/delocalized electronic excitations in the Na2F molecule which represents a test example for nonstoichiometric alkali–halides with one excess electron. The aim is to develop a method for the investigation of time–dependent laser induced processes in clusters which is capable to extract the leading physical effects responsible for the controlled excitation dynamics and for the evolution of the non–equilibrium states. KW - Physics KW - Optical physics KW - Molecular physics Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5640 VL - 9 IS - 1 SP - 393 EP - 397 ER - TY - JOUR A1 - Hartmann, Michael A1 - Heidenreich, Andreas A1 - Pittner, Jiřı́ A1 - Bonačić-Koutecký, Vlasta A1 - Jortner, Joshua T1 - Ultrafast Dynamics of Small Clusters on the Time Scale of Nuclear Motion JF - The Journal of Physical Chemistry A N2 - We present a theoretical study of the multistate dynamics of the Ag3-/Ag3/Ag3+ system on the time scale of nuclear motion, as explored by femtosecond pump−probe negative ion-to neutral-to positive ion (NENEPO) spectroscopy. The dynamics of the Ag3 cluster initiated from its linear transition state involves configurational relaxation, intracluster collision, and onset of IVR, resonant and dissipative IVR and vibrational equilibration, whose time scales were determined. Our analysis reveals that theory is essential for the elucidation of the rich dynamic information regarding geometrical change, completion of IVR, and vibrational coherence effects in the NENEPO femtosecond signals. KW - Physical chemistry KW - Nuclear motion Y1 - 1998 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. VL - 102 IS - 23 SP - 4069 EP - 4074 ER - TY - JOUR A1 - Hartmann, Michael A1 - Pittner, Jiřı́ A1 - Dam, Huub van A1 - Veyret, Vincent A1 - Bonacic-Koutecký, Vlasta T1 - Theoretical exploration of stationary and of ultrafast spectroscopy of small clusters JF - Applied Physics B N2 - Stationary spectra offer information on the interplay between the structures and the nature of electronic excitations reflecting bonding properties, as shown by comparing Sin with Agn (n=4-6) clusters. In order to study the dynamical properties, simulations and analysis of femtosecond (fs) time-resolved pump–probe or pump–dump signals have been carried out, which allows us to determine the timescales and the nature of configurational changes versus internal vibrational relaxation (IVR) in electronic ground or excited states. For this purpose we have developed a multi-state ab initio molecular dynamics (involving ground as well as adiabatic or non-adiabatic excited electronic states) on the timescale of the nuclear motion, using the time evolution of a thermal ensemble in the Wigner representation. The combination of ab initio quantum-chemical methods used for the molecular dynamics ‘on the fly’ and the Wigner-distribution approach for the description of the motion of the nuclei also allowed the accurate determination of pump–probe and pump–dump signals under temperature-dependent initial conditions. We use this novel combination of methods to investigate the dynamics in excited states of non-stoichiometric NanFn-1 clusters with a single excess electron. The timescales of the structural relaxation in excited states versus intramolecular vibrational relaxation processes have been determined, as illustrated for the example of Na4F3. This is the first study of the system with 15 degrees of freedom for which the dynamics in the excited states has been carried out without the precalculation of the energy surfaces. KW - Physics KW - Laser technology KW - Engineering Y1 - 2000 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5693 VL - 71 IS - 3 SP - 343 EP - 349 ER - TY - JOUR A1 - Bonačić-Koutecký, Vlasta A1 - Hartmann, Michael A1 - Pittner, Jiřı́ A1 - Dam, Huub van T1 - Theoretical exploration of ultrafast spectroscopy of small clusters JF - International Journal of Quantum Chemistry N2 - The central issue in femtosecond (fs) time resolved spectroscopy of clusters is the investigation of geometric relaxation and internal vibrational redistribution (IVR) after optical excitation in a nonequilibrium configuration of nuclei by laser photoelectron excitation, and corresponding time delayed probing by multiphoton-ionization. For this purpose, we have developed multistate ab initio molecular dynamics involving adiabatic ground and excited electronic states, as well as nonadiabatic coupling between them, using the time evolution of initial thermal ensemble in Wigner representation. The combination of ab initio quantum chemical methods, used for the adiabatic and nonadiabatic molecular dynamics “on the fly,” and the Wigner distribution approach for the description of the motion of the nuclei allowed us the accurate determination of pump-probe and pump-dump signals also under temperature dependent initial conditions. The connection between simulated pump-probe signals and the underlying dynamics of nuclei involving adiabatic electronic ground states has been first established for the example of the Agequation image/Ag3/Agequation image systems, and compared with experimental negative-to-neutral-to-positive NeNePo pump-probe signals. Our simulations reproduced the experimental NeNePo results and determined, in addition to the timescales of geometric relaxation, the conditions under which the resonant or dissipative IVR, as well as vibrational coherence, should be found in the experimental pump-probe signals. This can be realized in the zero electron kinetic energy NeNePo-ZEKE experiments, which are in progress. The above combination of methods has been recently extended to the analysis of the timescales as well as of the dynamics in excited electronic states of the nonstoichiometric NanFn−1 (n=2–4) clusters with the single excess valence electron. Our approach allows the simulation of femtosecond NeExPo-pump-probe and NeExNe-pump-dump signals, based on an analytic formulation which utilizes temperature dependent ground state initial conditions of neutral system (Ne); an ensemble of trajectories carried out either on the adiabatic electronic excited state (Ex), or on both the excited and the ground states through nonadiabatic coupling in connection with the fewest switching hopping algorithm for the investigation of the dynamics of the system; and either the cationic (Po) or the neutral ground state (Ne) for the probing step. The choice of the systems has been made in order to determine the timescales of processes involving (1) fast geometric relaxation leaving the bonding frame intact versus IVR, as during the adiabatic dynamics in the first excited state of Na4F3, being the smallest prototype of F-colored centers in the bulk; and (2) the photo-isomerization process through the conical intersection during nonadiabatic dynamics due to the long amplitude motion, as in the Na3F2 cluster after breaking of one metallic and one ionic bond, representing the first example of a five atomic cluster in the gas phase exhibiting conical intersection between the ground and the first excited state. In both cases, full complexity of the problem has been considered taking into account all degrees of freedom. The investigated systems represent important test cases for providing the conceptual framework of ultrafast dynamics in finite systems. KW - Quantum chemistry KW - Ultrafast spectroscopy Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5712 VL - 84 IS - 6 SP - 714 EP - 739 ER - TY - JOUR A1 - Hartmann, Michael A1 - Pittner, Jiřı́ A1 - Bonačić-Koutecký, Vlasta A1 - Heidenreich, Andreas A1 - Jortner, Joshua T1 - Theoretical exploration of femtosecond multi-state nuclear dynamics of small clusters JF - The Journal of Chemical Physics N2 - We investigate ultrafast multi-state nuclear dynamics in a triatomic cluster. In particular, we explore how the intracluster nuclear dynamics of the Ag−3/Ag3/Ag+3 system is reflected in the femtosecond pump-probe negative ion-to neutral-to positive ion (NENEPO) signals. The nuclear dynamics is based on classical trajectories on the ground electronic adiabatic state potential hypersurfaces obtained from accurate ab initio quantum chemistry calculations. The nuclear dynamics of Ag3 initiated from the linear transition state involves distinct sequential processes of configurational relaxation to the triangular configuration, intracluster collisions, and the onset of IVR, resonant, and dissipative IVR, and vibrational equilibration. We determined the timescales for these processes and discussed their dependence on the initial cluster temperature. The Wigner representation of the density matrix was utilized to simulate the NENEPO-zero kinetic energy (NENEPO-ZEKE) signal and the total (integrated over the photoelectron energy) NENEPO signal. We show how geometrical change, completion of IVR and vibrational coherenceeffects can be identified in the NENEPO signals. A comparison of the calculated NENEPO signals with the available experimental data is presented. KW - Cluster dynamics KW - Femtosecond dynamics Y1 - 1998 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. VL - 108 IS - 8 SP - 3096 EP - 3113 ER - TY - JOUR A1 - Bonačić-Koutecký, Vlasta A1 - Pittner, Jiřı́ A1 - Pou-Amérigo, Rosendo A1 - Hartmann, Michael T1 - Ab-initio study of structural and optical properties of nonstoichiometric alkalimetal- oxides JF - Zeitschrift für Physik D N2 - Structural and optical properties of nonstoichiometric LinO and NanO (n = 3, 4) clusters containing one and two excess electrons are studied using ab-initio methods accounting for electron correlation. We show that calculated absorption patterns are excellent fingerprints of structural and bonding properties. The optical response of Li4O and Na4O clusters with the most stable tetrahedral type structures is characterized by a common feature, that is the appearance of a dominant intense transition in infrared regime although excess of electrons are not localized, as it is the case for small alkali-halide clusters, with cuboid corner vacancy (surface F-center in finite systems). KW - Inorganic Chemistry KW - Physical chemistry Y1 - 1997 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5748 VL - 40 IS - 1 SP - 445 EP - 447 ER - TY - JOUR A1 - Röseler, J. A1 - Hartmann, Michael T1 - An exactly solvable model for the large polaron JF - Zeitschrift für Physik B N2 - We present an exactly diagonalizable model Hamiltonian for the large polaron derived by analyzing the variational ansatz by Haga-Larsen (HL) for the Fröhlich Hamiltonian. The lowest energy eigenvalue of the model Hamiltonian for fixed wave numbers reproduces the energy of the variational ansatz by Haga-Larsen and is, therefore, an upper bound with respect to the corresponding energy eigenvalue of the Fröhlich Hamiltonian. This is valid for any momentum which is proven by extending the Haga-Larsen approach. Furthermore, since all integrations can be performed analytically, the model Hamiltonian is easily tractable. The energy eigenvalue spectrum of the model Hamiltonian is studied below and above the phonon-emission threshold. The quality of the model Hamiltonian is determined by the variational ansatz of Haga and Larsen. Incorporating an improved energy-momentum relation, a generalized model Hamiltonian is derived possessing a larger validity range with respect to the coupling strength. Furthermore, a second exactly diagonalizable model Hamiltonian based on improved Wigner-Brillouin perturbation theory due to Warmenbol, Peeters, and Devreese (WPD) is presented. It is briefly demonstrated that one is able to construct all mentioned model Hamiltonians also in the 2D polaron problem. In contrast to the 3D case, where the HL-type model Hamiltonian possesses the higher quality for any momentum, in the 2D case, it works well only for small momenta. For large momenta, only the WPD-type model Hamiltonian describes the energy-momentum relation correctly. We demonstrate the usefulness of the model Hamiltonian concept by exactly calculating the one-electron Green’s function for all mentioned model Hamiltonians and comment why significant advantages of the model Hamilton concept for the treating of low-dimensional systems (planar semiconducting quantum-well structures) can be expected. KW - Inorganic Chemistry KW - Engineering KW - Condensed Matter Physics Y1 - 1997 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5782 VL - 102 IS - 4 SP - 531 EP - 540 ER - TY - JOUR A1 - Hartmann, Michael A1 - Chernyak, Vladimir Y. A1 - Mukamel, Shaul T1 - Real-space coupled-oscillator approach to the radiative decay of conjugated polymers JF - Physical Review B N2 - The optical response of conjugated polymers is calculated using a one-dimensional tight-binding model with Coulomb interactions, and adopting the multipolar form for the electromagnetic field Hamiltonian. By formulating the problem using the reduced single-electron density matrix and its evolution in Liouville space, we obtain a real-space description for the elementary electronic excitations. A unified expression for the linear response including radiative decay, which is valid for arbitrary chain size compared with the optical wavelength, is described. For small sizes it shows exciton confinement effects on the radiative decay and for larger sizes it fully incorporates polariton effects. KW - Conjugated polymers Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5813 VL - 52 IS - 4 SP - Keine Angabe - No details EP - Keine Angabe - No details ER - TY - CHAP A1 - Santos, C. A1 - Suisky, D. A1 - Enders, P. A1 - Neugebauer, F. A1 - Hartmann, Michael A1 - Röseler, J. A1 - Knoch, R. A1 - Heimbrodt, Wolfram T1 - Magnetooptical Anisotropy in Semimagnetic Materials: the Interplay of Strain and Magnetic Field T2 - European Workshop on II-VI Semiconductors, Linz N2 - Keine Angabe - No details KW - Magnetooptical anisotropy KW - Semimagnetic material Y1 - 1994 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER - TY - CHAP A1 - Santos, C. A1 - Suisky, D. A1 - Neugebauer, F. A1 - Hartmann, Michael A1 - Heimbrodt, Wolfram A1 - Röseler, J. T1 - Magnetooptical Anisotropy in Superlattices and Quantum Wells T2 - 22nd International Conference on the Physics of Semiconductors, Vancouver N2 - Keine Angabe - No details KW - Engineering Y1 - 1994 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER - TY - CHAP A1 - Gocek, Pawel A1 - Hartmann, Michael A1 - Schleusener, Heinz A1 - Timčák, Geza T1 - Webportal using Web 2.0 Technology for the Špis Region T2 - 5th International Conference on Perspectives of rural tourism in the New Europe, Košice N2 - Portals are called web sites which are designed to offer services and/or an outline of special subjects. They have been developed as fast as information data bases and electronic communication facilities were extended. Recently, portals with geographically referenced information became important and popular for different fields like geo information systems of cities (see e. or the presentation of economically relevant data in the context of regional marketing, foreign direct investment or tourism by indicating important objects like public institutions, companies, hotels, sights, etc. on maps. In this manner they may contribute to the improvement of industrial structure and the marketing of a region. For representing geographical data on maps, applications with special client-server-architecture have to be developed. There are different solutions for the Internet using HTML and JavaScript, Flash or Java Applets. In our contribution we discuss currently available solutions and show an alternative approach. Our solution is based on the Java Applet technology and Asynchronous JavaScript and XML (Ajax). This technology is part of the web solutions known as Web 2.0 which is strongly discussed and developed in the present. Our results are demonstrated as a user-friendly web application with data of the Slovakian region Špis (Zips). An extended version of this web solution could be nicely incorporated into a modern concept for tourism of the Špis region. KW - Web 2.0 KW - Tourism Y1 - 2006 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Full text not available for copyright reasons. SP - 48 EP - 54 ER - TY - CHAP A1 - Kohler, L. A1 - Hartmann, Michael A1 - Schleusener, Heinz A1 - Timčák, Geza T1 - Web 2-presentation of regional data T2 - 5th International Conference on Perspectives of rural tourism in the New Europe, Košice N2 - Web portals and many Internet solutions contain objects with a geographical reference such as the position of a company or a tourist attraction. Existing maps are protected by copyright. The licence fee is high and it is very expensive and complicated to create own maps. Freely useable and suitable maps for presentations, such as open source, do not exist – although the project OpenGeoDB is growing day after day. Recently, however some changes occurred. After a registration, Yahoo and Google offer interfaces to their map data for non-commercial users. This can be used for free. The interfaces offer advanced user possibilities for accessing maps, which are mostly high resolution ones, using the Web 2 methods. We show how to integrate Google´s API interface into one's own web applications and finally, how regional data, stored in a database, can be presented by this solution. Currently, Google does not have sufficiently detailed maps for Eastern Europe yet. Nevertheless, our web solution uses data of the region Zips (Špis) in Slovakia. It demonstrates how geo-based data can be used for supporting regional marketing concepts by Web 2 in the future. KW - Regional data Y1 - 2006 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. SP - 55 EP - 58 ER - TY - CHAP A1 - Hartmann, Michael A1 - Lieberum, Uta A1 - Plewka, Tomas A1 - Sauer, Petra A1 - Schweikart, Joachim A1 - Yossa Nou b ikou, Jean-Jacques A1 - Schleusener, Heinz T1 - Development of Geo-Based interactive Web Portals for Joint Ventures-Problems and Challenges T2 - Informatika a felsőoktatásban, Debrecen N2 - Keine Angabe No details KW - Geo-based KW - Web portals Y1 - 2005 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER - TY - CHAP A1 - Hartmann, Michael A1 - Peuker, Sigrid A1 - Njinkeu, Jules T1 - Erneuerbare Energien für die Infrastrukturentwicklung ländlicher Regionen in Mosambik T2 - Armutsbekämpfung und Infrastrukturentwicklung in Mosambik, Bad Honnef N2 - Das Potential erneuerbarer Energien für die Infrastrukturentwicklung insbesondere der ländlichen Region. KW - Erneuerbare Energie KW - Infrastrukturentwicklung Y1 - 2006 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER - TY - JOUR A1 - Hartmann, Michael T1 - Non equilibrium Green's function approach to nonadiabetic molecular dynamics JF - Journal of Physical Chemistry A N2 - Keine Angabe - No details KW - Molecular Dynamics KW - Physical chemistry Y1 - 2002 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. VL - 106 SP - Keine Angabe - No details EP - Keine Angabe - No details ER - TY - JOUR A1 - Mitrić, Roland A1 - Hartmann, Michael A1 - Stanca, B. A1 - Bonačić-Koutecký, Vlasta A1 - Fantucci, P. T1 - Ab Initio Adiabatic Dynamics Combined with Wigner Distribution Approach to Femtosecond Pump−Probe Negative Ion to Neutral to Positive Ion (NeNePo) Spectroscopy of Ag2Au, Ag4, and Au4 Clusters JF - Journal of Physical Chemistry A N2 - Ultrafast ground state nuclear dynamics of small coinage metal clusters is theoretically explored in the framework of negative ion to neutral to positive ion (NeNePo) femtosecond pump−probe spectroscopy with the aim to determine the scope and perspective of this technique. This approach involves the preparation of an initial ensemble in the anionic ground state of the cluster, one-photon detachment by the pump pulse, the propagation of the system on the neutral electronic ground state, and detection via the cationic ground state by a time-delayed ionizing probe pulse. The calculations of the NeNePo-ZEKE signals under the condition of zero kinetic energy electrons are based on the combination of the Wigner distribution approach and ab initio molecular dynamics (MD) “on the fly” in the framework of gradient-corrected DFT for the propagation of an ensemble of classical trajectories and involves the average over the entire phase space. We have chosen examples of Ag2Au and Au4 to investigate time scales and the character of isomerization processes that are influenced by a local minimum corresponding to an energetically high-lying isomer with the structure related to the initial anionic structure. Capture of the nuclei within the local minimum takes place with dephased (Ag2Au) or nondephased (Au4) vibrational relaxation. Structural relaxations leading to isomerization processes are in both cases of delocalized nature and take place after 1 ps. In contrast, the Ag4 cluster represents an example for which isomerization processes do not occur, since rhombic structures with slightly different bond lengths are global minima of the anionic and neutral ground states. Therefore, the relaxation dynamics is characterized by regular oscillations, which serve as fingerprints of structural properties. On the basis of the analysis of pump−probe signals and underlying dynamics, this contribution provides information about conditions under which structural properties of gas-phase clusters (global and local minima) and isomerization processes can be observed in the framework of the NeNePo-ZEKE type of spectroscopy. The latter is important in the context of applicability of this technique to the investigation of cluster reactivity. KW - Physical chemistry Y1 - 2001 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. VL - 105 IS - 39 SP - 8892 EP - 8905 ER - TY - JOUR A1 - Bonačić-Koutecký, Vlasta A1 - Hartmann, Michael A1 - Pittner, Jiřı́ T1 - Theoretical exploration of ultrafast spectroscopy of small clusters JF - The European Physical Journal D N2 - We present the ultrafast multistate nuclear dynamics involving adiabatic and nonadiabatic excited states of non-stoichiometric halide deficient clusters (NanF) characterized by strong ionic bonding and one-excess electron for which the "frozen ionic bonds" approximation has been justified allowing to consider the optical response of the single excess electron in the effective field of the other electrons. We combined the Wigner-Moyal representation of the vibronic density matrix with the ab initio multi state molecular dynamics in the ground and excited electronic states including the nonadiabatic couplings calculated "on the fly" at low computational demand. This method allows the simulation of femtosecond pump-probe and pump-dump signals based on an analytical formulation, which utilizes temperature dependent ground state initial conditions, an ensemble of trajectories carried out on the electronic excited state as well as on the ground state after the passage through the conical intersection in the case of nonadiabatic dynamics and for probing either in the cationic state or in the ground state. The choice of the systems we presented has been made in order to determine the timescales of the fast geometric relaxation leaving the bonding frame intact as during the dynamics in the first excited state of Na4F3, and of the bond breaking processes leading to conical intersection between the first excited state and the ground state as in Na3F2. The former is the smallest finite system prototype for an surface F-center of bulk color centers. The latter allows to study the photo isomerization in full complexity taking into account all degrees of freedom. In the case of Na4F3 after the fast geometric relaxation in the excited state leading to deformed cuboidal structure without breaking of bonds, different types of internal vibrational redistribution (IVR) processes have been identified in pump-dump signals by tuning the dump laser. In contrast, from the analysis of the pump-probe signals of Na3F2 cluster, the timescales for the metallic and the ionic bond breaking, as well as for the passage through conical intersection have been determined. Finally the conditions under which these processes can be experimentally observed have been identified. KW - Optical Physics KW - Molecular Physics Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5536 VL - 16 SP - 133 EP - 138 ER - TY - JOUR A1 - Hartmann, Michael A1 - Mitrić, Roland A1 - Stanca, B. A1 - Bonačić-Koutecký, Vlasta T1 - Theoretical investigation of the ultrafast NeNePo spectroscopy of Au4 and Ag4 Clusters JF - The European Physical Journal D N2 - Ultrafast ground state nuclear dynamics of Au4 and Ag4 is theoretically explored in the framework of negative ion - to neutral - to positive ion (NeNePo) pump-probe spectroscopy based on the ab initio Wigner distribution approach. This involves the preparation of a nonequilibrium neutral ensemble by pump induced photodetachment of a thermal anionic ground state distribution, gradient corrected DFT classical trajectory simulations "on the fly" on the neutral ground state, and detection of the relaxation process of the ensemble in the cationic ground state by a time-delayed probe pulse. In Au4, the initially prepared linear structure is close to a local minimum of the neutral state giving rise to characteristic vibrations in the signals for probe wavelength near the initial Franck-Condon transition. A timescale of ~1 ps for the structural relaxation towards the stable rhombic D neutral isomer was determined by the increase of the signal for probe wavelength in vicinity of the vertical ionization energy of the rhombic structure. In contrast, the relaxation dynamics in Ag4 is characterized by normal mode vibrations since both the initially prepared anionic ground state and the neutral ground state have rhombic minimum geometries. Thus, time-resolved oscillations of pump-probe signals are fingerprints of structural behaviour which can be used experimentally for the identification of particular isomers in the framework of NeNePo spectroscopy. KW - Molecular physics KW - Optical physics Y1 - 2001 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5542 VL - 16 SP - 151 EP - 155 ER - TY - RPRT A1 - Hartmann, Michael A1 - Peuker, Sigrid A1 - Njinkeu, Jules T1 - Der Energiepark Berlin Marzahn/Hellersdorf: Studie und Abschlussdokumentation zum Entwicklungsprojekt "Erneuerbare Energien im Kontext der Entwicklungszusammenarbeit mit Unternehmen" N2 - Keine Angabe - No details KW - Erneuerbare Energien KW - Energiepark Y1 - 2004 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER - TY - JOUR A1 - Hartmann, Michael A1 - Pittner, Jiřı́ A1 - Bonačić-Koutecký, Vlasta T1 - Ab initio nonadiabatic dynamics involving conical intersection combined with Wigner distribution approach to ultrafast spectroscopy illustrated on Na3F2 cluster JF - The Journal of Chemical Physics N2 - We present a theoretical study of a femtosecond photo isomerization process due to a nonadiabatic radiationless decay from the first excited state through a conical intersection occurring in one of the nonstoichiometric halide-deficient clusters with one excess electron (Na3F2). This is an extension of the adiabatic dynamics study presented in the accompanying paper [J. Chem. Phys. 114, 2106 (2001)] for other members of the NanFn−1 series characterized by a strong ionic bonding for which the “frozen ionic bonds” approximation has been justified, allowing consideration of the optical response of the single excess electron in the effective field of the other electrons. In this contribution we outline the extension of the ab initio Wigner-distribution approach to nonadiabatic molecular dynamics which combines the Wigner–Moyal representation of the vibronic density matrix with the ab initio multistate molecular dynamics in the ground- and excited electronic states including the nonadiabatic coupling computed “on the fly” in connection with the fewest-switches hopping algorithm. This scheme allows accounting for temperature-dependent initial conditions, for the propagation in the excited state and in the ground state after the passage through the conical intersection, and for probing in the cationic ground state as well as for deriving analytic expressions for the pump–probe signals which utilize an ensemble of classical trajectories obtained at low computational demand. Our approach permits investigation of the photo isomerization through the conical intersection due to the long amplitude motion in the Na3F2 system in full complexity, taking into account all degrees of freedom. After breaking of one metallic and of one ionic bond the conical intersection occurs at the linear geometry and involves states of different symmetry which differ in the translocation of the one excess electron or positive charge localized at the Na atom from one end to the other of the system and separates two isomers with Cs and C2v structures. From the analysis of the nonadiabaticdynamics, the time scales for the metallic bond breaking of ∼90 fs and for the ionic bond breaking of ∼220 fs, for the passage through the conical intersection after ∼0.4 ps and for the internal vibrational energy redistribution (IVR) of more than 0.9 ps for the individual isomers, have been determined. The simulated fs pump–probe signals confirm the above results and provide the information about the experimental conditions such as laser frequencies and pulse duration under which bond breaking of different type as well as the population of each of the two isomers after the passage through the conical intersection can be identified. In this contribution we show that the mechanism of the photo isomerization at a conical intersection due to a long amplitude motion can occur in atomic clusters and is not necessarily limited to organic photochemistry. KW - Wigner distribution KW - Chemical physics Y1 - 2001 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. VL - 114 IS - 5 SP - 2123 EP - 2136 ER - TY - JOUR A1 - Hartmann, Michael A1 - Pittner, Jiřı́ A1 - Bonačić-Koutecký, Vlasta T1 - Ab initio adiabatic dynamics involving excited states combined with Wigner distribution approach to ultrafast spectroscopy illustrated on alkali halide clusters JF - The Journal of Chemical Physics N2 - We investigate the ultrafast multistate nuclear dynamics involving adiabatic electronic excited states of nonstoichiometric halide deficient clusters (NanFn−1) characterized by strong ionic bonding and one excess electron, which is localized either in the halide vacancy or on the alkali atom attached to the ionic subunit depending on the cluster size. For this purpose we developed an ab initio adiabatic nuclear dynamics approach in electronic excited and ground states “on the fly” at low computational demand by introducing the “frozen ionic bonds” approximation, which yields an accurate description of excited states considering the excitation of the one excess electron in the effective field of the other n−1 valence electrons involved in the ionic bonding. We combined this multistate dynamics approach with the Wigner–Moyal representation of the vibronic density matrix forming the ab initio Wigner distribution approach to adiabatic dynamics. This method allows the simulation of femtosecondNeExPo-pump–probe and NeExNe-pump–dump signals based on an analytic formulation which utilizes temperature-dependent ground-state initial conditions (Ne), an ensemble of trajectories carried out on the electronic excited state (Ex) for the investigation of the dynamics of the system, and either the cationic (Po) or the ground state (Ne) for the probing step. The choice of the systems has been made in order to determine the time scales of processes involving (i) metallic bond breaking such as during the dynamics in the first excited state of Na2F, and (ii) fast geometric relaxation leaving the bonding frame intact as during the dynamics in the first excited state of Na4F3. The bond-breaking process via a conical intersection involving nonadiabatic dynamics will be presented in the accompanying paper [Hartmann et al., J. Chem. Phys. 114, 2123 (2001)]. The dynamics in the first excited state of Na2F from triangular-to linear-to triangular structure gives rise to fast geometric relaxation due to Na–Na bond breaking at the time scale of ∼90 fs but no signature of internal vibrational energy redistribution (IVR) is present in NeExNe-pump–dump signals since the broken metallic bond prevents the coupling between stretching and bending modes. Instead, anharmonicities of the bending periodic motion have been identified. In contrast, in the case of Na4F3, which is the smallest finite system for a surface F-center prototype of bulk color centers, after the geometric relaxation in the excited state of ∼100 fs leading to the deformed cuboidal type of structure without breaking of bonds, different types of IVR have been identified in NeExNe signals by tuning the dump laser: one-mode selective energy leaving IVR, resonant, and restricted energy arriving IVR corresponding to the selection of different parts of the phase space. Dissipative IVR could not be identified in NeExNe signals of Na4F3 at low initial temperature on the time scale up to 2 ps in spite of 15 degrees of freedom. Due to similar structural and electronic properties such as F centers in bulk, these findings can serve as guidance for establishing the time scales for geometric relaxation and IVR in excited states of larger systems. KW - Wigner distribution KW - Chemical physics Y1 - 2001 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. VL - 114 IS - 5 SP - 2106 EP - 2122 ER - TY - JOUR A1 - Gocek, Pawel A1 - Hartmann, Michael A1 - Schleusener, Heinz T1 - Modern Technologies in Client-Server Architecture for Geo-based Interactive Web Portals JF - Journal of Universal Computer Science N2 - The internet is an unlimited growing and most comfortable information and communication base. In this context, web portals on the internet play an important role created for combining communication facilities and information data bases. An increasing number of portals involve web-based map applications to integrate geographic information for the representation of economical and other records. Web-based map applications are typically designed in a client-server architecture. Different solutions exist using especially HTML and JavaScript, Flash or Java applets. We discuss these possibilities and point out an alternative solution. Particularly, we show how to use Java Applet Technology and Asynchronous JavaScript and XML (Ajax) in this field. Finally, we report about our results as a complete, flexible map service solution which is available on the internet. An adapted kind of solution will be used by a geo-based marketing portal for offering information about the economic situation, social and cultural aspects and natural facts of regions to support joint-ventures inside the European Union. KW - Web-based services KW - Map services KW - XML KW - Geo-base KW - Java Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5335 VL - 12 IS - 9 SP - 1208 EP - 1214 ER - TY - CHAP A1 - Gocek, Pawel A1 - Hartmann, Michael A1 - Schleusener, Heinz T1 - Modern Technologies in client-server Architecture for Geo-Based Webportals: represented by examples for Companies in Food Technology and Food Industry T2 - Proceedings of the 7th International Conference on Food Science, Szeged N2 - In the last decade, portals on the WWW have been extensively developed for different applications in e-business, e-commerce, e-government or science and are used as an information and communication base. Recently, due to the progression of web- technologies, new user-friendly features could be added into portals. Among them the incorporation of geographic informations became most important since many relevant data are related to space. In such a way the value and the appropriate visualization of the relevant information as well as the ability to investigate the interrelation between different data could be reached (Bernhardt, 02). Geo-based web portals combine the features of common portals like searching for keywords or navigating with geo information systems (GIS). For a certain target group they provide a unique presentation of all relevant information within a region or a market, and provide user specific communication tools. In this context, providing maps is one of the main characteristics of geo-based web portals. Creating a geo-referenced map is a challenging and complex task since all relevant geo data like streets, objects, information of the landscape etc. have to be known and incorporated into the GIS. Therefore, a geo-object in the geo-based web portal has to contain both the geo-data and the content related data. Geo-data describe the structure of an object in space whereas the content related data provide additional attributes associated with the properties of the object (Dickmann & Zehner 2001). From the point of the architecture, a web-based map application consists of two essential components - the server and the client part. Typically, the server component is responsible for providing geographical information according to the client's request and returns the data and images suitable for the visualization back to the client application. The client component provides the user with a graphical user interface (GUI). Its main tasks are collecting the user input data and communicating with the server in order to retrieve the information as well as to provide interactive mechanisms for representing analyzing the results. The communication between the client and the sever component via a HTTP port is based on a defined request-response protocol. Typical solutions are implemented using JavaScript, Java applets or Flash and are discussed in more detail in the next section. In this contribution we describe an alternative approach using the Java Applet Technology, Asynchronous JavaScript and XML (Ajax). It's application for offering informations of companies operating in the field of food technology and food industry is shown. In such a way it represents a realization of our recently developed concept of a geo-based web portal (Hartmann et al, 05). KW - Geo-base KW - Web-based services KW - Food technology KW - Food industry Y1 - 2006 ER - TY - CHAP A1 - Hartmann, Michael A1 - Takahashi, Akira A1 - Mukamel, Shaul T1 - Soliton and Exciton Effects on Photoexcited Conjugated Polymers T2 - 2nd International Topical Conference on Optical Probes of Conjugated Polymers and Fullerenes, Salt Lake City N2 - Keine Angabe - No details KW - Engineering KW - Conjugated polymers Y1 - 1994 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER - TY - JOUR A1 - Hartmann, Michael A1 - Mukamel, Shaul T1 - Femtosecond four wave mixing spectroscopy of conjugated polymers JF - The Journal of Chemical Physics N2 - Time‐resolved four wave mixing (4WM) signals of conjugated polymers are calculated using a density matrix approach and the Hartree–Fock approximation. The influence of the Coulomb interaction as well as size effects on the nonlinear optical response are examined. For the Hückel model (no Coulomb interaction), quantum beats due to the coherent excitation of several band states are found for small sizes, and photon echo‐like behavior is obtained for infinite size. The Coulomb interaction changes the nature of the response and gives rise to a broad delayed signal whose temporal profile is determined by the dephasing time. KW - Optical polymers KW - Dephasing KW - Band models Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5897 VL - 99 IS - 3 SP - 1597 EP - 1606 ER - TY - CHAP A1 - Wang, Hong Xiang A1 - Takahashi, Akira A1 - Hartmann, Michael A1 - Mukamel, Shaul T1 - Quantum Confinement and Nonlinear Optical Response of Conjugated Molecules T2 - International Symposia on Optoelectronic Packaging and Interconnects, Los Angeles N2 - Keine Angabe - No details KW - Engineering KW - Conjugated molecules Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5911 ER - TY - JOUR A1 - Kim, Dai-Sik A1 - Shah, Jagdeep A1 - Cunningham, J. E. A1 - Damen, T. C. A1 - Schäfer, Wilfried A1 - Hartmann, Michael A1 - Schmitt-Rink, Stefan T1 - Giant excitonic resonance in time-resolved four-wave mixing in quantum wells JF - Physical Review Letters N2 - We report a strong (300:1) excitonic resonance in time-resolved (100 fs) four-wave mixing in GaAs quantum wells as a function of the incident photon energy and show that it results from the large difference in the dephasing rates of excitons and free carriers. We conclude that excitons dominate even when they make up only a small fraction of the excited states. These results, in conjuction with new results in exciton-phonon scattering, provide new insights into previous studies performed with spectrally broad ultrashort pulses. KW - Physics Y1 - 1992 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. VL - 68 SP - 1006 EP - Keine Angabe - No details ER - TY - JOUR A1 - Hartmann, Michael A1 - Schäfer, Wilfried T1 - Real Time Approach to Relaxation and Dephasing Processes in Semiconductors JF - Physica Status Solidi (B) N2 - Starting from the kinetic equations for the nonequilibrium Green's functions, a practical method is proposed which allows to solve the set of equations for the two-time propagators numerically. In contrast to the usual semiconductor Bloch equations with phenomenological damping relaxation and dephasing processes are treated microscopically for the case of coupling to a bath of LO-phonons. Beside a standard approximation for the treatment of LO-phonon scattering, no further approximations are performed. For the low-density limit we compare exact results with approximate treatments, as the Marcovian and non-Marcovian approximations resulting from a density matrix approach. First results concerning nonlinear optical properties are presented. KW - Physics KW - Real time approach KW - Semiconductors Y1 - 1992 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-5980 VL - 173 IS - 1 SP - 165 EP - 176 ER - TY - CHAP A1 - Hartmann, Michael A1 - Schäfer, Wilfried A1 - Schmitt-Rink, Stefan T1 - Time-resolved and time-integrated four-wave-mixing signals of two-dimensional magneto-excitons T2 - International Meeting on Optics of Excitons in Confined Systems, Giardini Naxos N2 - Keine Angabe - No details KW - Physics KW - Optics Y1 - 1991 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Full text due to copyright not available. ER - TY - THES A1 - Hartmann, Michael T1 - Realzeitkinetik und Kinetik der Abschirmung optisch hochangeregter Halbleiter N2 - Keine Angabe - No details KW - Physik KW - Kinetik KW - Halbleiter Y1 - 1991 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER - TY - JOUR A1 - Hartmann, Michael A1 - Zimmermann, R. A1 - Stolz, Heinrich T1 - Kinetics of Screening in Optically Excited Semiconductors JF - Physica Status Solidi (B) N2 - Kinetic equations for the density correlation and density-density response function are derived. Solving these equations numerically and comparing its solution with the adiabatic approximation the change in the transmitted spectrum of a single electronic transition is calculated where a red-shift can be observed. Es werden kinetische Gleichungen für die Di Dichtekorrelationsfunktion und die Dichte-Dichte-Responsefunktion abgeleitet. Die numerische Lösung dieser Gleichungen wird mit der adiabatischen Approximation verglichen. Die Berechnung der Änderung im Transmissionsspektrum für einen einzelnen elektronischen Übergang ergibt eine Rotverschiebung. KW - Physics KW - Kinetics Y1 - 1990 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-6028 VL - 159 IS - 1 SP - 35 EP - 42 ER - TY - JOUR A1 - Zimmermann, R. A1 - Hartmann, Michael T1 - Theory of the dynamical stark effect of excitons in CdS JF - Journal of Crystal Growth N2 - The dynamical Stark effect of excitons in CdS bulk crystals has been measured recently using differential transmission spectroscopy (DTS). A general DTS formula is derived taking into account exciton-exciton interaction. A perculiar influence of the pump and test polarization on its magnitude is predicted. Concerning the dephasing (transverse relaxation), coupling to optical phonons is treated on a microscopic level. A density-matrix approach leads to the imaginary part of the exciton-phonon self energy. Its strong frequency dependence which shows up as a non-Markoff relaxation strongly suppresses the relaxation for the pump pulse at large detuning. A more sophisticated approach using the non-equilibrium Green function gives deeper insight into the underlying scattering processes. KW - Physics Y1 - 1990 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Full text due to copyright not available. VL - 101 IS - 1-4 SP - 341 EP - 345 ER - TY - JOUR A1 - Zimmermann, R. A1 - Hartmann, Michael T1 - Resonant and Off-Resonant Light–Matter Interaction in Semiconductors Kinetics and Transients JF - Physica Status Solidi (B) N2 - Kinetic problems for off-resonance excitation (dynamical Stark effect) and resonant excitation (laser-induced gaps) are studied. Within the Hartree-Fock theory, Stark shift and bleaching of the exciton line are evaluated. The influence of photon statistics on light-induced gaps is investigated. Open questions concerning the transient response are clarified. Es werden kinetische Probleme für nichtresonante Anregung (dynamischer Stark-Effekt) und resonante Anregung (laserinduzierte Lücken) betrachtet. Im Rahmen der Hartree-Fock-Theorie werden Stark-Verschiebung und Oszillatorstärkenänderung für die Exzitonlinie berechnet. Der Einfluß der Photon-Statistik auf die lichtinduzierten Lücken wird untersucht. Einige offene Fragen des Kurzzeit-Response werden geklärt. KW - Physics KW - Kinetics KW - Semiconductors Y1 - 1988 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0298-opus4-6048 VL - 150 IS - 2 SP - 365 EP - 378 ER - TY - JOUR A1 - Hartmann, Michael A1 - Zimmermann, R. A1 - Stolz, Heinrich T1 - Carrier Kinetics in a Semiconductor with Light-Induced Gaps JF - Physica Status Solidi (B) N2 - Due to the influence of a strong electromagnetic field an induced gap is expected to occur in the band structure of a semiconductor. In this paper the influence of the damping by electron–phonon collisions and by recombination on the new band structure is investigated. Taking into account damping kinetic equations for the electrons are derived and discussed with the help of calculations. Unter dem Einfluß eines starken elektromagnetischen Feldes kommt es in der Bandstruktur eines Halbleiters zur Ausbildung eines Zusatzgaps. In dieser Arbeit wird der Einfluß der Dämpfung durch Elektron–Phononstöße und Rekombination auf die neue Bandstruktur untersucht. Weiterhin werden kinetische Gleichungen unter Berücksichtigung der Dämpfung abgeleitet und an Hand von numerischen Berechnungen diskutiert. KW - Physics KW - Kinetics KW - Semiconductors Y1 - 1988 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. VL - 146 IS - 1 SP - 357 EP - 369 ER - TY - THES A1 - Hartmann, Michael T1 - Ladungsträgerkinetik und Kinetik der Abschirmung optisch hochangeregter Halbleiter N2 - Keine Angabe - No details KW - Realzeitkinetik KW - Kinetik KW - Halbleiter Y1 - 1991 N1 - Volltext aus urheberrechtlichen Gründen nicht verfügbar. Fulltext due to copyright not available. ER -