STRUCTURAL KINETICS BY TIME-RESOLVED GAS ELECTRON-DIFFRACTION - COHERENT NUCLEAR-DYNAMICS IN LASER-EXCITED SPATIALLY ANISOTROPIC MOLECULAR ENSEMBLES

Novel equations for molecular intensities are presented which can be u sed in analyses of time-resolved electron diffraction (TRED) data reco rded from spatially oriented laser-excited molecules. The formalism is applicable to nondissociative processes and to studies of the nuclear dynamics of dissociation and predissociation phenomena. With the help of quantum dynamics, specific model calculations were performed with the new theoretical expressions for various purposes: to determine the effects of non-equilibrium vibrational distributions, of the vibratio nal recurrence of wave packets, and of isotopic substitution on TRED i ntensities; and to compare the quantum-dynamical calculations of TRED intensities with the previous Gaussian wave packet approach. The study is a continuation of ongoing efforts to create a theoretical base for structural kinetic studies of laser-excited species using gas electro n diffraction.