Solvent-Solute Interactions

Solvent-solute interactions play a key role in solution-phase chemistry. These interactions not only stabilize intermediate states by solvation of the corresponding valence charge distributions, but modify energy barriers thereby altering transition states, and allow for ultrafast solvent dynamics in response to solute perturbations (e. g. < 100 fs inertial responses of common solvents). Solvent-solute interactions are thus often essential in determining ground-states and steering chemical reactions in solution-phase chemistry.

We seek to understand the role of solvation and solvation dynamics upon external perturbations through excitation of electronic and vibrational degrees of freedom. While extended collective motions of solvent molecules and their corresponding spectral density in the THz spectral region are important for solvation dynamics, ultrafast local probes of the solute are useful in understanding the influence of solvation (dynamics) on the solute's constituents during chemical reactions.

Both, vibrational and core-level transitions extend over length scales from functional groups to individual atoms, making them excellent spectroscopic probes of solute-solvent interactions. While vibrational transitions can largely be associated with structural dynamics, core-level transitions report on valence electronic distributions as well structural parameters such as bond lengths and geometries. We hope to gain new insight into the role of solvent-solute interactions by exciting collective solvent motions and employing a broad range of spectral probes from meV to keV.