Infrared spectrum of matrix-isolated CO and CO photoproduct from OCS photolysis

Experimental studies on the photodissociation of OCS in both crystalline ar gon and nitrogen are presented. OCS photodissociation is followed by high-r esolution interferometric infrared spectroscopy of the CO photoproduct. In solid nitrogen, the photogenerated CO molecule is produced in a damaged sit e that can be partially healed by thermal annealing. In contrast, the photo generated CO site in argon does not revert to the sites occupied by neat CO /Ar matrices, even when annealed at 40 K. Model calculations on the infrare d spectral line shape and orientational motion of the matrix-isolated CO mo lecule support a structural interpretation of the experimental findings. Th e calculations use an Ar-CO intermolecular potential along with an Art pair potential to minimize the energy of a finite section of the full matrix un der two broad structural constraints and with both single- and double-subst itutional site assumptions. The line shape is calculated via a CO center-of -mass motion weighted perturbation of the isolated CO intramolecular potent ial by the field of static Ar neighbors.