Resonance heterodyne optical Kerr spectroscopy of solvation dynamics in water and D2O

We have used the technique of time resolved resonance heterodyne optical Kerr effect to measure the ultrafast solvation dynamics of rhodamine 800 (R800) and 3,3′-diethylthia-tricarbocyanine bromide (DTTCB) in water and D2O. We find a significant isotope effect in the picosecond range for R800 but we do not reveal it for DTTCB. We explain the R800 results by a specific solvation due to formation (breaking) of an intermolecular solute-solvent hydrogen bond. Another important part of the experimental data is a bimodal solvation correlation function with an ultrafast femtosecond component < 100 fs.