Dissociation dynamics of I[sub 2](B)-Ar: Rotational population distributions of I[sub 2](B,v) fragments from the T-shaped and linear complexes.

Optical-optical double resonance techniques have been used to examine the dissociation dynamics of I[sub 2](B)-Ar. Rotational population distributions were characterized for the I[sub 2](B,v) fragments. Vibrational predissociation of the T-shaped complex yielded fragments with smooth rotational distributions. The high-energy limits of the distributions were consistent with events that channeled almost all of the available energy into product rotation. These data indicate a dissociation energy for I[sub 2](B)-Ar of D[sub 0](C[sub 2v])=220 cm[sup -1]. Most initial states of the complex produced bimodal rotational population distributions, but a few gave Boltzmann-type product distributions. The dependence of the character of the distribution on the initially excited state suggests that predissociation is mediated by intramolecular vibrational energy redistribution. Dissociation of linear I[sub 2](B)-Ar yielded fragments with Boltzmann type rotational population distributions. Excitation of the complex within the bound regions of the B-X transition gave rotationally cold I[sub 2](B,v) fragments, consistent with direct dissociation from a near-linear geometry. Excitation above the B state dissociation limit produced I[sub 2](B,v) fragments via caged recombination. The rotational distributions of these fragments were cold, supporting earlier studies that attribute the one atom cage recombination to the linear isomer. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]