THEORETICAL AND EXPERIMENTAL SPECTROSCOPICAL STUDY OF SOLVATION DYNAMICS

We developed theoretically and experimentally the principles of a spec troscopical method based on resonance transient population gratings fo r quantitative description of solvation dynamics of large molecules in liquid solutions. The solvation dynamics of LDS 750 in N -monosubstit uted amide, ethylacetamide and butylacetamide have been measured. This class of solvents exhibits exceptionally large static dielectric cons tants. The solvation dynamics of LDS 750 in all solvents consists of u ltrafast as well as dow components. A theoretical basis for solvation dynamics study of complex molecules in solutions by resonance nonlinea r spectroscopy has been developed. We have introduced a model of an op tically active non-Markovian oscillator (NMO) for the description of s olvation dynamics in nonlinear optical experiments in a systematic way . It has been shown that an optically active Brownian oscillator and d ifferent NMO models can be considered as successive long time approxim ations to a real correlation function of an optically active oscillato r. The model of two NMOs with an exponential memory function describes accurately various experimental and computer simulations data of ultr afast solvation dynamics. We have compared the latter model with moder n theories of solvation.