Time resolved infrared absorption studies of geminate recombination and vibrational relaxation in OCIO photochemistry

Abstract

The first ultrafast time-resolved infrared absorption studies of the geminate recombination and vibrational relaxation dynamics of aqueous chlorine dioxide (OCIO) were presented. The rapid increase in optical density observed at the lowest probe frequencies demonstrated that the asymmetric-stretch coordinate serves to accept excess vibrational energy following geminate recombintion faster than the symmetric stretch. The measured evolution in optical density was compared to two proposed models for the vibrational- relaxation dynamics along the asymmetric-stretch coordinate. The comparison demonstrated that the perturbation model derived from molecular dynamics is capable of qualitatively reproducing the observed kinetics.