Dynamics of optically induced anisotropy in an ensemble of asymmetric top molecules in the gas phase

A complex theoretical and experimental investigation of the evolution of optically induced anisotropy in an ensemble of free asymmetric tops under collisionless conditions is performed. The dynamics of the orientational correlation functions is studied and the results of femtosecond measurements of the relaxation of the anisotropy of perylene fluorescence in the gas phase are reported. The results obtained are interpreted in terms of the theory developed. It is shown that, in contrast to steady-state anisotropy, the time kinetics of optically induced anisotropy yields more complete and typical data on the dynamics of vector correlations in an ensemble of molecules.