Suche
Anzeige der Dokumente 121-127 von 127
Dissertation
Relativistic LCAO with Minimax Principle and New Balanced Basis Sets
(2011-01-13)
Relativistic density functional theory is widely applied in molecular calculations with heavy atoms, where relativistic and correlation effects are on the same footing. Variational stability of the Dirac Hamiltonian is a very important field of research from the beginning of relativistic molecular calculations on, among efforts for accuracy, efficiency, and density functional formulation, etc. Approximations of one- or two-component methods and searching for suitable basis sets are two major means for good projection ...
Dissertation
Development of UNCD-based multielectrode arrays for neuronal measurements
(2017-07-26)
The work in hand will show how some of diamond’s extraordinary features can be utilized in bio-applications especially for in vitro cultures of neuronal cells. Diamond has proven itself as an excellent material for bio-applications such as simple fluorescent microarrays over bioFET (field effect transistor) to bioMEMS (microelectro-mechanical systems). The reason does not only lie in its best known properties namely extreme hardness and high refractive index, but in its unique chemistry. As one of the modifications ...
Dissertation
Analytical Study of Light Propagation in Highly Nonlinear Media
(2009-08-17)
The present dissertation is devoted to the construction of exact and approximate analytical solutions of the problem of light propagation in highly nonlinear media. It is demonstrated that for many experimental conditions, the problem can be studied under the geometrical optics approximation with a sufficient accuracy. Based on the renormalization group symmetry analysis, exact analytical solutions of the eikonal equations with a higher order refractive index are constructed. A new analytical approach to the construction ...
Dissertation
Asymmetric magnetization reversal processes in exchange-biased microstructures
(2023)
Over the last decades, the exchange bias (EB) effect has captured the attention of the research community striving for high-density logic memory devices and sensitive sensor technologies based on bi-, multilayered, or patterned magnetic thin film systems. Macroscopically, the EB manifests in a horizontal shift of the ferromagnetic remagnetization loop and an enhancement of the coercivity, both connected to the induced unidirectional anisotropy (UDA) at the exchange-coupled ferromagnetic/antiferromagnetic interface. ...
Dissertation
Ultraschnelle kohärente Kontrollmethoden für die nichtlineare Mikroskopie und Spektroskopie
(2023-11-28)
Ultrakurze Laserpulse im Nanojoule-Energiebereich auf der Femto- bis Pikosekunden-Zeitskala ermöglichen die Erzeugung immenser Feldstärken bei Fokussierung auf wenige Quadratmikrometer Fläche. In diesem Szenario wirken starke Kräfte auf die Elektronensysteme von Atomen und Molekülen im Fokus ein, so dass sich die linearen optischen Eigenschaften von Stoffen ändern können – nichtlineare Eigenschaften treten zutage. Mit einem Pulsformer kann auf die breiten Spektren ultrakurzer Laserpulse per spektraler Phasenmodulation ...
Dissertation
Immobilization of Neodymium Complexes on Semiconductor Surfaces and Processing of GaAs-based Photonic Crystals
(2024)
Lanthanide ion luminescence exhibits characteristic narrow emission bands ranging from VIS to NIR along with relatively long emission lifetimes which makes them attractive for applications in lighting, sensing, and display technologies. The focus of this dissertation lies on the optical characterization of newly synthesized neodymium complexes bearing phosphonate ester ligands and the fabrication of photonic crystal (PhC) cavities. Micro-photoluminescence (PL) spectroscopy is used to investigate the NIR emission bands ...
Dissertation
Towards the investigation of ultrafast dynamics in chiral systems using free-electron lasers
(2024)
Chiral molecules are life’s building blocks, making the study of their ultrafast processes a pursuit across various fundamental research fields. The results presented in this dissertation contain methodological, technical and scientific advancements that pave the way for future time-resolved, site-specific investigations into chiral photochemistry of randomly orientated molecules, using photoelectron circular dichroism and free-electron lasers. The high-repetitionrate free-electron lasers EuXFEL and FLASH2 will soon ...