Research

Our group works on (multidimensional) spectroscopy of ultrafast molecular processes, studies their control on a quantum-mechanical level and is engaged in the research field of ultrafast nano-optics. Dynamic processes in molecules proceed on a timescale of few femtoseconds up to nanoseconds. We develop and apply spectroscopic methods to make such phenomena visible. Key to obtaining this insight is the ability to manipulate the temporal evolution of extremely short light pulses (“pulse shaping”). One of our goals is to combine ultrahigh spatial and ultrahigh temporal resolution. Thus we monitor and control, for example, charge and energy transfer in molecular aggregates, chemical reaction dynamics, or plasmon propagation in nanostructures.

Our research concentrates on molecular spectroscopy, photochemistry and reaction dynamics. Here "dynamics" means to unravel the microscopic details of a chemical reaction. Although we predominately study isolated molecules in the gas phase, we also investigate chemical reactions in solution. The focus is on reactive open-shell species, like hydrocarbon radicals and carbenes that are relevant in the chemistry of combustion processes, the atmosphere and interstellar space. We use various complementary experimental methods. like time-resolved spectroscopy, vibrational, electronic and photofragment spectroscopy, and photoionisation by synchroton radiation. As some projects are carried out at external facilities (i.e. synchrotron radiation sources), we foster a number of international cooperations.

Processes at nanosurfaces are key for growth, properties and function of nanomaterials. We develop tools and methods to study phenomena at the nanoparticle-solvent interface. We focus on single-wall carbon nanotubes as model systems which are explored at the ensemble and single particle levels by combining a variety of continuous wave, time-resolved and ultrafast optical probes with microfluidic technology and colloidal chemistry.

The Mitric group works on the development of methods for simulation and laser control of light-induced dynamics in complex molecular systems based on mixed quantum-classical approaches. For this purpose, the efficient (semi-)classical description of the nuclear dynamics is combined with the quantum chemical treatment of the electronic structure, including nonadiabatic effects and the interaction with light. Our aim is to gain a fundamental understanding of photochemistry and photophysics in complex systems and to apply this knowledge to the development of novel materials. The present research areas include:
a) Light-induced nonadiabatic photodynamics of molecules in complex environments, metal clusters and hybrid nanostructures
b) Coherent control of photochemistry in complex systems by shaped laser pulses
c) Theory of ultrafast spectroscopy and molecular imaging
d) Theoretical design of novel optical, catalytic and plasmonic materials

The Röhr group develops theoretical methods to understand and rationally design light-induced processes in electronically coupled molecular systems. Central to our work is the development of analytic many-body electronic-structure approaches for correlated excited states in molecular aggregates and complex environments, combined with quantum-classical dynamics. By linking these methods to inverse design and machine-learning strategies, we aim to derive predictive structure-function relationships and enable the rational design of photofunctional molecular systems.