Ultrafast charge transfer and isomerization dynamics of molecules in solution
The aim of this project is to unravel the coupling of electronic and structural degrees of freedom during chemical reactions of molecules in solution. Molecules will be optically excited with a femtosecond pump pulse and their dynamic response will be followed with short X-ray probe pulses. Different X-ray spectroscopic techniques will give element-selective insight into different aspects of the dynamic pathways: Time-resolved femtosecond resonant inelastic X-ray scattering (RIXS) maps the evolution of electronic processes such as orbital population and depopulation. This is a novel way of following charge as it transfers and localizes. In addition, femtosecond RIXS gives access to the evolution of the occupied and unoccupied electronic structure of the molecule with time and as it undergoes configurational changes. Time-resolved X-ray absorption spectroscopy (XAS) will be particularly sensitive to the structural changes of the molecule and gives insight into the influence of the interactions with the solvent (via hydrogen bonds e.g.). This approach represents the most direct way of probing chemical bonding of short-lived intermediate states.
The aim of this project is to unravel the coupling of electronic and structural degrees of freedom during chemical reactions of molecules in solution.
This project is complementary to the investigations in projects P1 and P4 (mapping of the structural evolution of the same molecules but isolated in the gas phase and as nanocrystals) and P3 (energy and charge transfer of the same molecules on surfaces). The optically triggered experiments on molecules in solutions using photon-in photon-out techniques performed here are the starting point for future investigations of equilibrium dynamics with X-ray scattering (P5) and will enable studying thermally activated or THz-pump initiated chemical reactions (P10).