Hydrogen-bond dynamics after optical excitation probed by femtosecond vibrational spectroscopy

Summary form only given. Local solute-solvent interactions play a fundamental role in nonequilibrium liquid dynamics. For instance, a change of solute dipole moment induced by ultrafast optical excitation initiates a complex solvation process for which the interaction between the solute and the first solvent shell is very important. Solvation processes have mainly been studied by monitoring changes in the electronic spectra of the solute, e.g. the red shift of fluorescence emission, techniques that give very limited insight into the dynamics of local structures. Very recently we introduced vibrational spectroscopy of specific functional groups of the solute in order to monitor the dynamics of hydrogen bonds between coumarin solutes and protic polar solvents after electronic excitation of the solute. In the contribution we extend this technique to hydrogen-bonded complexes between coumarin 102 (C102) and phenol as a proton donor. In this system we monitor for the first time the site-specific dynamics of both proton donor and acceptor in an intermolecular hydrogen bond on the femtosecond time scale.