### Recent Submissions

• #### Strong magnetic fields and unusual flows in sunspots ﻿

(2023-02-06)
This thesis presents a study of sunspots, which are the most prominent features observed on the solar surface. Their structure is governed by the magnetic field. The umbra and penumbra of sunspots harbor different strengths ...
• #### STED microscopy with two-photon photoactivation in the visible range & Application of generative adversarial networks for image reconstruction in STED microscopy ﻿

(2023-01-31)
The resolution limit of classical optical far-ﬁeld microscopes was broken with the invention of super-resolution microscopy. Today, a variety of these techniques achieving diﬀerent degrees of resolution exist. Image formation ...
• #### Transport and dynamical properties of electron-phonon coupled systems ﻿

(2023-01-31)
In this thesis, I investigate the transport and dynamical properties of electron-phonon coupled systems using numerical methods. I focus on the one-dimensional Holstein model, which incorporates both polaron and charge ...
• #### Simulations of Cosmological Structure Formation with Nonrelativistic Scalar Fields ﻿

(2023-01-20)
Nonrelativistic, self-gravitating scalar fields are of current interest in several scenarios of cosmological structure formation. This includes the gravitational clustering of dark matter in the late-time Universe which ...
• #### Far-from-Equilibrium Quasiparticle Dynamics in Graphene ﻿

(2023-01-17)
Comprehending far-from-equilibrium many-body interactions is one of the major goals of current ultrafast condensed matter physics research. Here, a particularly interesting but barely understood situation occurs during a ...
• #### Experimentelle Untersuchung von thermohalinen Treppen in doppelt-diffusiver Konvektion ﻿

(2023-01-12)
This study deals with the modeling of a laboratory experiment where steady states as well as transients of double diffusive staircases can be observed by Particle Image Velocimetry (PIV) in a fluid layer. A stabilizing ...
• #### High-Resolution Reflection Microscopy via Absorbance Modulation ﻿

(2023-01-11)
The properties of composite materials are primarily governed by their microstructural features, which can vary in size from a few nanometres to several micrometres. Optical microscopy is one of the primary tools for ...
• #### Nanoscale Friction Measurements on Manganite Thin Films: Which Material Properties are Important? ﻿

(2023-01-05)
Although the phenomenon of friction has been known to mankind for millennia, the underlying mechanisms that ultimately lead to the conversion of kinetic/mechanical energy into heat remain unclear. Based on Bowden and Tabor's ...
• #### Proton Beam Writing ﻿

(2022-12-16)
Proton beam writing (PBW) is a mask-less 3D structuring method that uses a focused, relatively high energy Proton beam, followed by an etching step to create free standing 2D and 3D structures in a large variety of target ...
• #### New Approaches to Cryo-EM Image Processing ﻿

(2022-12-16)
Using cryo-electron microscopy (cryo-EM), it is possible to resolve structures of biological macromolecules by averaging numerous projections of macromolecules (particle images) frozen in vitrified ice and imaged using ...
• #### Local excitation of confined molecule-surface hybrid systems ﻿

(2022-11-28)
Molecule-surface hybrid systems promise solutions for a variety of technological challenges – including the development of efficient catalysts as well as of molecular electronic devices. In this work, different molecule ...
• #### Physical modeling of motile and sedimenting plankton: from simple flows to turbulence ﻿

(2022-11-22)
Planktonic microorganisms play a fundamental role in oceanic ecology and chemical cycles. Different planktonic species are found at various levels of the oceanic trophic chain, ranging from photosynthetic organisms to ...
• #### Theory of solar oscillations in the inertial frequency range ﻿

(2022-11-16)
Recent observations have revealed that we lack a fundamental understanding of the large scale (with spherical harmonic degrees $l < 60$) flows in the Sun. Flows at these large scales are strongly influenced by rotation. ...
• #### Higher Order Electroweak and QCD Corrections in e+e−μ+μ− production at LHC ﻿

(2022-11-09)
This thesis focuses on improving the theoretical modelling of the process pp → e+e−μ+μ− at LHC by including both EW and QCD higher-order perturbative corrections. The EW corrections are studied at NLO fixed order and in ...
• #### Dynamics and Self-organization of Crowded Active Systems ﻿

(2022-10-20)
The perplexing and intriguing world of biological systems has inaugurated a new research field in statistical physics: out-of-equilibrium systems, known as active matter that mimic systems in the biological world around ...
• #### Axion Miniclusters: Formation, Structure and Observational Signatures ﻿

(2022-09-29)
The axion is one of the leading candidates for cosmological dark matter. It arises as the pseudo-Goldstone boson of a spontaneously broken global U(1) symmetry. If this symmetry is broken after inflation, cosmic string ...
• #### Technologiebezogene Professionalisierung angehender Physiklehrkräfte - Entwicklung und Evaluation eines Lehrkonzepts in der Astrophysik mit digitalen Medien ﻿

(2022-09-09)
This thesis discusses the development and empirical evaluation of a university course in the form of an astrophysics tutorial that focuses on teaching and learning with digital media. Framed by design-based research, an ...
• #### How does stellar convection impact the detection of small planets at high radial velocity precision? ﻿

(2022-08-15)
One of the big driving forces behind exoplanet research is the search for an Earth-twin to answer the old question of whether or not humanity is alone in the universe. According to simple logic as well as our current ...
• #### Investigation of the Influence of Correlations on Photovoltaic Energy Conversion in Hot Polaron Solar Cells ﻿

(2022-08-08)
In semiconductor single junction solar cells fundamental limitations are given by the two major intrinsic loss mechanisms: a) inability to absorb photons with energies below the band and b) thermalization of photon energies ...
• #### Stochastic field theory of viscoelastic solids: a quantitative study of phononic friction ﻿

(2022-07-27)
Identifying the relevant dynamics of solids that give rise to friction is an active field of study. It includes electronic and phononic degrees of freedom, but the latter seems to be of particular significance. For instance, ...