The one-atom cage effect in I2(B)–Ar: Evidence that caging is inefficient for the T-shaped isomer

Abstract

Caged recombination is observed when the binary I2–Ar complex is excited to energies above the B state dissociation limit. The recombination mechanism has been the subject of several previous investigations. Two alternative models have been proposed; Nonadiabatic recombination in a T-shaped complex, or adiabatic recombination in linear I2–Ar. In the present study, fluorescence depletion measurements were used to test these models. Fluorescence resulting from caged recombination could not be depleted using the well-known resonances of T-shaped I2–Ar. Instead, depletion via a diffuse band system previously assigned to the linear I2–Ar was observed. These results are consistent with the adiabatic recombination model. Geminate recombination of I2 in a He supersonic expansion is also reported.