Distribution of Vibrational States of CO(2) in the Reaction O((1)D) + CO(2) from Time-Resolved Fourier Transform Infrared Emission Spectra

Abstract

A mixture Of O(3) and CO(2) was irradiated with light from a KrF laser at 248 nm; time-resolved infrared emission Of CO(2) in the region 2000-2400 cm(-1) was observed with a Fourier transform spectrometer. This emission involves one quantum in the asymmetric stretching mode (nu(3)) Of CO(2) in highly vibrationally excited states. The band contour agrees satisfactorily with a band shape calculated based on a simplified polyad model of CO(2) and a vibrational distribution estimated through a statistical partitioning of energy of similar to 13 000 cm(-1), similar to 3100 cm(-1) smaller than the available energy, into the vibrational modes Of CO(2). From this model, approximately 44% and 5% of the available energy of O((1)D) + CO(2) is converted into the vibrational and rotational energy of product CO(2), respectively, consistent with previous reports of similar to 50% for the translational energy. An extent of rotational excitation Of CO(2) much smaller than that expected from statistical calculations indicates a mechanism that causes a small torque to be given to CO(2) when an O atom leaves the complex CO(3) on the triplet exit surface of potential energy, consistent with quantum-chemical calculations.