Institut für Physikalische und Theoretische Chemie

Research Interests

I am interested in ultrafast energy and electron transfer processes, their characteristics and the methods used to described them. This includes their initiations by excitation and ionization, their time evolution as well as their time-resolved measurement.

A few examples are listed below.

Time-resolved spectroscopy

We are building time-dependent theoretical models that describes the Interatomic Coulombic Decay, which are flexible enough to incorporate a variety of effects and time-resolved experimental techniques and sufficiently general to hold for both atoms and molecules. It allows to gain time-resolved information about electronic decay processes by proposing new experiments as well as to interpret experimental results.

Electronic Decay Processes in Large Systems

The characteristics of electronic decay processes are influenced by the environment. Ionization and excitation energies are altered by the delocalization of the excited state over multiple entities as well as electronic (de)stabilization. The latter is famously utilized in Auger electron spectroscopy.

The lifetimes can be severely changed as well. For Interparticle Coulombic Decay processes (ICD) the decay width depends linearly on the number of closest neighbours and is further increased by other decay partners further away. This effect can decrease the lifetime by an order of magnitude and thereby allow the ICD to outperform the Auger-Meitner process in some cases.

We have developed the program HARDRoC, which we use to study the effect of the environment on ICD processes. Its development allowed to increase the system size from 13 atoms to several thousand atoms.

Many-body quantum dynamics

Trapped Fermions Escape

When several fermions like electrons, protons and even classes of atoms or molecules are trapped in a confined space by a potential with not too high barriers, they have two options to escape: either by going over the barrier if they have enough energy to do so or by using the quantum mechanical tunneling process and going through the barrier. In this work we present the efficient implementation of a theoretical method which allows us to study the motion of fermions and how they escape in an exact way. We reveal that fermions escape over the barrier together, while they travel alone when they tunnel through the barrier.

Relativistic Quantum Chemistry

Relativistic effects manifest themselves as scalar-relativistic effeects or spin-orbit coupling, thereby affecting the properties of molecules, characteristics of chemical reactions and the likelyhood or even the possibility of processes to occur at all, e.g., intersystem crossing.

We investigate the influence of relativistic effects with a focus on lifetimes of electronic decay processes and in connection to ultrafast spectroscopy.