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 presen ted. With a reasonable choice of parameters for the potential, three-d imensional quantum dynamics calculations yield a nonmonotonic variatio n in the main resonance decay constant with initial I-2 vibrational ex citation nu'. This behavior is attributed to a few-state intramolecula r vibrational energy redistribution (IVR) mechanism. The main resonanc es contain large contributions from zero-order ''bright'' states with nu' quanta in I-2 and zero-point energy in the van der Waals modes. Th ey 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 con stants. We also investigate the quantum dynamics of certain excited vd W stretch/ bend states, which show related behavior. Recent experiment al work, however, suggests that no unusual NR effects occur in ArI2. P ossible reasons for this apparent discrepancy between theory and exper iment are suggested.