VIBRATIONAL PREDISSOCIATION AND INTRAMOLECULAR VIBRATIONAL-ENERGY REDISTRIBUTION - 3-DIMENSIONAL QUANTUM DYNAMICS OF ARI2

A detailed theoretical study of an empirical potential model for ArI2(nu') --> Ar + I-2(nu<nu'). With Zero total angular momentum, is presented. With a reasonable choice of parameters for the potential, three-dimensional quantum dynamics calculations yield a nonmonotonic variation in the main resonance decay constant with initial I-2 vibrational excitation nu'. This behavior is attributed to a few-state intramolecular vibrational energy redistribution (IVR) mechanism. The main resonances contain large contributions from zero-order ''bright'' states with nu' quanta in I-2 and zero-point energy in the van der Waals modes. They also contain varying degrees of ''dark'' states associated with nu' - 1 and nu' - 2 quanta in I-2 and stretch/bend excitations in the van der Waals modes. The varying degree of interaction between bright and dark states leads to the strong variation in main resonance decay constants. We also investigate the quantum dynamics of certain excited vdW stretch/ bend states, which show related behavior. Recent experimental work, however, suggests that no unusual NR effects occur in ArI2. Possible reasons for this apparent discrepancy between theory and experiment are suggested.