RESONANCE HETERODYNE OPTICAL KERR SPECTROSCOPY OF SOLVATION DYNAMICS IN WATER AND D2O

We have used the technique of time resolved resonance heterodyne optic al Ken effect to measure the ultrafast solvation dynamics of rhodamine 800 (R800) and 3,3'-diethylthia-tricarbocyanine bromide (DTTCB) in wa fer and D2O. We find a significant isotope effect in the picosecond ra nge for R800 but we do not reveal it for DTTCB. We explain the R800 re sults by a specific solvation due to formation (breaking) of an interm olecular solute-solvent hydrogen bond. Another important part of the e xperimental data is a bimodal solvation correlation function with an u ltrafast femtosecond component < 100 fs.