Abstract

In this paper we present new results on the photodissociation, geminate recombination, and vibrational relaxation of ${\text{I}}_{\overline{2}}$ in various solvents. The photodissociation of ${\text{I}}_{\overline{2}}$ involves localization of the excess charge on a recoiling I• photofragment. This charge again delocalizes as the I• and I⁻ geminately recombine. The "charge flow" associated with recombination and subsequent large-amplitude vibrational motion is believed to greatly accelerate the vibrational relaxation of the nascent ${\text{I}}_{\overline{2}}$. Coupling of the charge flow with accepting solvent modes leads to relaxation rates which are extremely fast and non-exponential, even near the bottom of the potential well. These results are in stark contrast to similar experiments performed on neutral I₂ which show nearly exponential vibrational relaxation rates that are an order of magnitude slower and are well-described by isolated binary interaction (IBC) theory.

© 1994 Optical Society of America