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Now showing items 41-50 of 63
Dissertation
A new perspective to strongly-interacting lattice fermions in the framework of density functional theory
(2020)
Die in dieser Arbeit formulierte Theorie betrachtet das Vielteilchenproblem wechselwirkender Fermionen auf einem Gitter aus einem neuen Blickwinkel.
Dissertation
Optimal Control of Quantum Information Tasks in Open Quantum Systems
(2020-07-30)
Every quantum system inevitably interacts with its environment. This is a fundamental requirement that allows us to control, measure and, in general, interact with quantum systems. In that respect, a quantum system's openness can be interpreted as prerequisite that enables quantum technologies in the first place. The latter are built to harness the intrinsic quantum mechanical behavior of quantum devices in order to build new, powerful technologies. However, a quantum system's openness also causes it to interact ...
Dissertation
High temperature-stable InGaAs QDs for the monolithic integration in external-cavity surface-emitting lasers
(2021)
Optically pumped vertical external-cavity surface-emitting lasers (VECSELs), also called semiconductor disk lasers (SDLs), benefit from the flexibility and versatility of the semiconductor material. With a simple cavity layout, fundamental transverse mode operation with a circular output beam and high beam quality is possible. They have excellent heat-sink properties and only require inexpensive multimode diode lasers for pumping. The complete VECSEL structure is only a few micrometers thick which leads to a strong ...
Dissertation
Synthese und Reaktivität eines cyclischen (Alkyl)(amino)carbens mit 1,1'-Ferrocenylen-Rückgrat
(2023-01)
Ziel der vorliegenden Arbeit war es, cyclische (Alkyl)(amino)carbene mit einem 1,1‘ Ferrocenylen-Rückgrat (fcCAACs) darzustellen und zu charakterisieren und somit eine Kombination aus bekanntermaßen jeweils höchst ambiphilen CAACs und N-heterocyclischen Carbenen mit 1,1‘-Ferrocenylen-Rückgrat (fcNHCs) zu schaffen. Durch das fc-Rückgrat sollten die Zielverbindungen eine im Vergleich zu bisher zugänglichen CAACs noch ausgeprägtere Ambiphilie besitzen und somit eine nochmals gesteigerte Reaktivität zeigen, insbesondere ...
Dissertation
Validation of a generalized model for the description of polycrystalline exchange-biased magnetic thin films
(2022)
Applications based on nano- and microscaled systems have become indispensable in many aspects in everyday life, industry, research and medicine. In this regard, thin film technology plays a crucial role with the physical properties of solids changing significantly when they are reduced to thin layers with thicknesses in the nanometer range. In this regime, a solid’s microstructure as well as boundary and surface effects start to dominate. A prominent example is the exchange bias effect, which results due to the ...
Dissertation
Fabrication and Investigation of Diamond Membranes for Photonic Nanostructures
(2023)
Due to its exceptional physical and chemical characteristics, diamond in a form of thin membranes is a particularly promising material for the fabrication of high-quality photonic devices. Especially for envisioned applications in quantum information technologies and communication, diamond gained, as a host material, an ever-increasing scientific interest based on remarkable properties of different color centers in its crystal lattice, e.g. nitrogen-vacancy centers, serving as single-photon emitters. As a high index ...
Dissertation
Darstellung, Eigenschaften und Reaktivität phosphorreicher Ferrocenophane
(2022-05)
Im Rahmen dieser Arbeit wurde ein präparativer Zugang zu phosphorreichen Ferrocenophanen entwickelt, die Substituenten mit variierenden sterischen und elektronischen Eigenschaften tra-gen und die Reaktivität dieser gegenüber Elektrophilen untersucht.
Die Reaktivitätsuntersuchungen des als Modellverbindung ausgewählten Diphospha-[2]fer-rocenophans L6a gegenüber Elektrophilen haben gezeigt, dass sowohl ein als auch beide Phos-phoratome selektiv, durch stöchiometrische Kontrolle mit Monoboran oder unterschiedlichen ...
Dissertation
Analysis of a Coupled Fluid-Elastic Interaction Problem
(2023-01)
In this thesis, a non-linear system of partial differential equations is studied, describing the motions of an elastic structure which is immersed into an incompressible viscous fluid. The displacement of the elastic structure is modelled by a Lamé system and the fluid velocity as well as the fluid pressure are described by the Navier-Stokes equations. The structure and the fluid are coupled via two boundary conditions at the interface which correspond to continuity of velocities and forces. As the elasticity is ...
Dissertation
Finite Element Simulations for the Design of Therapeutic Approaches for Retinal Diseases
(2022)
The retinal disease age-related macular degeneration is the most common cause of vision loss in industrialized countries. In this thesis, motivated by the drug (antibody) treatment of this disease, we designed long-term three dimensional Finite Element simulations of the drug distribution in the healthy human eye. The underlying model consists of a time-dependent convection-diffusion equation coupled to a stationary Darcy equation describing the flow of the aqueous humor through the vitreous medium. We replaced the ...
Dissertation
Application of Temporal Airy Pulses for investigating the origin of Laser Induced Periodic Surface Structures and for developing new tools in cell surgery and malignant tissue identification
(2023)
In this thesis, ultrashort Temporal Airy Pulses are used to study Laser Induced Periodic Surface Structures (LIPSS) in Part I and to enable the photoinjection of fluorescent markers into single living cells in Part II, Chapter 8. In both cases, the laser pulse excites a dielectric material (fused silica and water) and the special spatio-temporal dynamics of the interaction of a Temporal Airy Pulse with the dielectric is exploited to extend the shape of the excited region along the axis of laser propagation. For the ...