Probing ultrafast solvation dynamics using pump- probe spectroscopy and fluorescence-detected pump-probe spectroscopy

Abstract

So far, the time resolution for probing polar solvation dynamics has been limited to, from few tens of picoseconds using fluorescence lifetime measurement (by TCSPC technique) down to ~200 femtoseconds using fluorescence time-gating measurement (by fluorescence up-conversion technique). However, a substantial part (nearly 80%) of solvation completes within ~200 femtoseconds which demands probing early time solvation dynamics. We probed solvation dynamics using non-collinear pump probe spectroscopy by measuring the stimulated emission signal and collinear pump-probe spectroscopy by measuring only the fluorescence signal. We will present solvation dynamics studies of an NIR dye (DNTTCI) in two polar solvents (ethanol and ethylene glycol) using degenerate pump probe spectroscopy at 800 nm as well as fluorescence detected pump-probe spectroscopy. Our results show that much of the difference in solvation correlation function is observed within 1 picosecond.