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Dissertation
Magnetic interactions between transition metal impurities and clusters mediated by low-dimensional metallic hosts: A first principles theoretical investigation
(2015-03-31)
The magnetic properties and interactions between transition metal (TM) impurities and clusters in low-dimensional metallic hosts are studied using a first principles theoretical method. In the first part of this work, the effect of magnetic order in 3d-5d systems is addressed from the perspective of its influence on the enhancement of the magnetic anisotropy energy (MAE). In the second part, the possibility of using external electric fields (EFs) to control the magnetic properties and interactions between nanoparticles ...
Dissertation
Theoretical study of magnetism, structure and chemical order in transition-metal alloy clusters
(2012-02-27)
Research on transition-metal nanoalloy clusters composed of a few atoms is fascinating by their unusual properties due to the interplay among the structure, chemical order and magnetism. Such nanoalloy clusters, can be used to construct nanometer devices for technological applications by manipulating their remarkable magnetic, chemical and optical properties. Determining the nanoscopic features exhibited by the magnetic alloy clusters signifies the need for a systematic global and local exploration of their ...
Dissertation
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Electron Dynamics Driven by Intense Coherent Femtosecond Laser Pulses: Dynamic Interference in Atoms and Photoelectron Circular Dichroism in Chiral Molecules
(2018-12)
Since humans have begun to explore nature, they came up with new ways and tools, which have been permanently improved. At some point, those tools allowed to look into the microworld and to study the quantum nature of matter. One of such tools to explore the quantum world is the light amplification by stimulated emission of radiation (laser). Since the first lasers were built almost 60 years ago, their capabilities improved permanently, allowing the study of hitherto-unknown physical phenomena. Two of such phenomena, ...
Dissertation
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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 ...
Dissertation
Adsorption kinetic investigations of phthalocyanine derivatives self assembled monolayers (SAMs) on gold: Temperature influence on the SAM formation process and quality
(2015-08-12)
The ordered nano-structured surfaces, like self-assembled monolayers (SAMs) are of a great scientific interest, due to the low cost, simplicity, and versatility of this method. SAMs found numerous of applications in molecular electronics, biochemistry and optical devices. Phthalocyanine (Pc) complexes are of particular interest for the SAM preparation. These molecules exhibit fascinating physical properties and are chemically and thermally stable. Moreover their complex structure is advantageous for the fabrication ...
Dissertation
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Control of Open Quantum Systems: Examples & Methods for Non-Markovian Dynamics
(2023)
Usually open quantum systems are considered to be under the influence of noise and therefore faulty. On the other hand, a controlled system is regarded as something stable and predictable. It is often neglected, that the two aspects are very closely related. A perfectly isolated quantum system will not be subject to environmental influences, but this makes it also impossible to interact with it in any manner. Controlling and measuring such a system is impossible and therefore of no technical relevance. Every system ...
Dissertation
A semi-phenomenological approach to the structure and transport properties of macromolecules in solution
(2006-08-03)
Motiviert durch die Lebenswissenschaften (Life sciences) haben sich Untersuchungen zur Dynamik von Makromolekülen in Lösungen in den vergangenen Jahren zu einem zukunftsweisenden Forschungsgebiet etabliert, dessen Anwendungen von der Biophysik über die physikalische Chemie bis hin zu den Materialwissenschaften reichen. Neben zahlreichen experimentellen Forschungsprogrammen zur räumlichen Struktur und den Transporteigenschaften grosser MolekÄule, wie sie heute praktisch an allen (Synchrotron-) Strahlungsquellen ...
Dissertation
Metallische Nanopartikel auf Quarz
(2014-08-20)
This work presents the developement of an chemically stable and easy to produce in situ sensor for fast and reliable detection of polycyclic aromatic hydrocarbons (PAH) in low nanomolar concentrations. Metallic nanoparticles on dielectric substrates werde used for the rst time with surface enhanced Raman spectroscopy (SERS) in combination with shifted excitation Raman difference spectroscopy (SERDS).
The preparation of the metallic nanoparticle ensembles with Volmer-Webergrowth is described first. The nanoparticles ...
Dissertation
Protein Folding Simulations: Confinement, External Fields and Sequence Design
(2010-04-08)
The present Thesis looks at the problem of protein folding using Monte Carlo and Langevin simulations, three topics in protein folding have been studied:
1) the effect of confining potential barriers,
2) the effect of a static external field and
3) the design of amino acid sequences which fold in a short time and which have a stable native state (global minimum).
Regarding the first topic, we studied the confinement of a small protein of 16 amino acids known as 1NJ0 (PDB code) which has a beta-sheet ...
Dissertation
Atomistic-continuum modeling of ultrafast laser-induced melting of silicon targets
(2016-03-16)
In this work, we present an atomistic-continuum model for simulations of ultrafast laser-induced melting processes in semiconductors on the example of silicon. The kinetics of transient non-equilibrium phase transition mechanisms is addressed with MD method on the atomic level, whereas the laser light absorption, strong generated electron-phonon nonequilibrium, fast heat conduction, and photo-excited free carrier diffusion are accounted for with a continuum TTM-like model (called nTTM). First, we independently consider ...