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Dissertation
Many-body theory of laser-induced ultrafast demagnetization and angular momentum transfer in ferromagnetic transition metals
(2014-08-07)
An electronic theory is developed, which describes the ultrafast demagnetization in itinerant ferromagnets following the absorption of a femtosecond laser pulse. The present work intends to elucidate the microscopic physics of this ultrafast phenomenon by identifying its fundamental mechanisms. In particular, it aims to reveal the nature of the involved spin excitations and angular-momentum transfer between spin and lattice, which are still subjects of intensive debate. In the first preliminary part of the thesis the ...
Dissertation
Theory of Vesicle Motion and Interpretation of Electrophysiological Experiments in Chromaffin Cells, Hippocampal Neurons and Neuromuscular Junctions
(2018-07-16)
Communication among secretory cells, neurons and other related cells is accompanied by a
process called exocytosis, which consists in the release of neurotransmitters into the intercellular space. The neurotransmitter molecules are transported inside vesicles, which move
towards the cell membrane. Once at an active site of the membrane, vesicles can undergo
fusion with the membrane. As a result of fusion, a pore in the membrane is produced, through
which neurotransmitter molecules leave the cell. Exocytosis is ...
Dissertation
Excitation of Phonons in Solids and Nanostructures by Intense Laser and XUV Pulses and by Low Energy Atomic Collision
(2016-02-17)
Intensive, ultrakurze Laserpulse regen Festkörper in einen Zustand an, in dem die Elektronen hohe Temperaturen erlangen, während das Gitter kalt bleibt. Die heißen Elektronen beeinflussen das sog. Laser-angeregte interatomare Potential bzw. die Potentialenergiefläche, auf der die Ionen sich bewegen. Dieses kann neben anderen ultrakurzen Prozessen zu Änderungen der Phononfrequenzen (phonon softening oder phonon hardening) führen. Viele ultrakurze strukturelle Phänomene in Festkörpern hängen bei hohen Laseranregungen ...
Aufsatz
An ab-initio calculation of the Coulomb explosion of N_2 after heavy-ion bombardement
(1978)
Self-consistent-field calculations for the total potential energy of highly ionized N_2 molecules are presented. We compare these calculations to the experimentally observed energy released in the Coulomb explosion of ionized N_2 molecules created after collision with fast heavy ions. The most important electronic states of the fragment ions are determined.
Aufsatz
Interchannel interactions and relaxation in the 2p auger spectra of Mg-like ions
(1992)
Relativistic Auger rates for the 2p spectra of Mg-like ions have been calculated in the atomic range 13 < Z < 36. We used the multiconfiguration Dirac-Fock method but beyond a simple frozen-orbital approach we include also relaxation for the bound electrons and the interchannel interaction between the continuum states. Both effects may alter the individual transition rates remarkably. This is analysed for a few selected states within the isoelectronic sequence. Weak transitions within the 2p spectra can be changed ...