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Dissertation
Optical Amplification in Disordered Waveguiding Systems
(2020)
Bei dem Phänomen der verstärkten Emission in ungeordneten Systemen handelt es sich um ein wiederentdecktes und über die letzten Jahrzehnte stark debattiertes Themengebiet in der Literatur. Diese Dissertation soll hierzu zwei experimentelle Ansätze bieten, wobei beide in der Lage sind, bei optischer Anregung entweder Random Lasing oder Verstärkte Spontane Emission zu zeigen.
In dieser Arbeit wird thermisch induzierte Faltenbildung (Wrinklebildung) als neuer Ansatz zur Herstellung von Streuzentren in wellenleitenden ...
Dissertation
Die koordinationschemische Ambivalenz zweier mesoionischer Triazoliumaminide
(2020-05)
Die vorliegende Arbeit beleuchtet die Koordinationschemie zweier Mesoionen, die in Abhängigkeit vom angebotenen Zentralatom als N-heterocyclische Carben- (NHC-) oder Amido-Liganden fungieren. Durch Tautomerisierung der Triazoliumaminid-Form zum korrespondierenden Amino-NHC ermöglichen das seit über einem Jahrhundert bekannte analytische Reagenz »Nitron« (1) sowie dessen in dieser Arbeit entwickeltes Alkyl-Homolog 1-tert-Butyl-4-methyl-1,2,4-triazol-4-ium-3-tert-butylaminid (2) einen bequemen Zugang zur Chemie der ...
Dissertation
Fabrication and characterization of diamond nanopillars, waveguides and AFM tips with incorporated color centers
(2020-06)
Diamond is a unique material with outstanding properties and the perfect host for different crystal defects in its lattice, so-called color centers, which provide exceptional spin properties, rendering them a promising platform for the development of novel devices and components in quantum information technologies (QIT) and quantum sensing applications. To overcome diamond's high internal reflection due to its high refractive index, color centers need to be incorporated in photonic diamond structures, leading to ...
Dissertation
Molecular-Frame Angular Distributions of Electrons Emitted by Photoionization and Interatomic Coulombic Decay
(2020)
The continuous refinement of the experimental and theoretical methods to study the electron angular emission distributions, and particularly in a molecule frame of reference, have contributed to a keen understanding of the structure of molecules and have provided deeper insight into fundamental physical phenomena.
Revealing many details of the ionization dynamics, the molecular-frame angular distributions (MFADs) of emitted electrons have been an appealing research topic for the last two decades. Owing to the ...
Dissertation
Energy landscapes and dynamics of magnetic nanostructures: disorder, structure, and magnetic field effects
(2020)
The static and dynamic magnetic properties of two-dimensional ensembles of dipole-coupled magnetic nanoparticles (NPs) are investigated from a theoretical perspective. Particular emphasis is put on the correlations between the geometrical arrangements of the NPs, their inherent structural disorder, and the cooperative magnetic dynamics of the nanostructures as a whole. To this aim a significant number of representative two-dimensional NP ensembles with different structural geometries and degrees of disorder are ...
Dissertation
Explicit Description Of Isogeny And Isomorphism Classes Of Drinfeld Modules Of Higher Rank Over Finite Fields
(2020)
When jumping from the number fields theory to the function fields theory, one cannot miss the deep analogy between rank 1 Drinfeld modules and the group of root of unity and the analogy between rank 2 Drinfeld modules and elliptic curves. But so far, there is no known structure in number fields theory that is analogous to the Drinfeld modules of higher rank r ≥ 3. In this thesis we investigate the classes of those Drinfeld modules of higher rank r ≥ 3 defined over a finite field L. We describe explicitly the Weil ...
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 ...