The decomposition of cyclobutanone vapor induced by infrared radiation from a pulsed CO2 TEA laser

Abstract

The decomposition of cyclobutanone vapor by infrared radiation from a pulsed CO2 TEA laser at 9.552 μm has been studied at pressures from about 0.1 to 10 Torr. The main decomposition path was [Formula: see text]while the reaction [Formula: see text]was much less important. Very minor amounts of propylene and acetylene were also observed. From the ratio of reaction [2] to reaction [1], information was obtained about the effective temperature of the decomposition and the energy of the decomposing molecules. With the laser beam unfocussed, the decomposition at pressures above about 3 Torr is adequately described as a thermal decomposition, controlled by the initial temperature attained and the rate of cooling of the irradiated gas. At lower pressures, and when the laser beam was focussed, direct excitation and decomposition of individual molecules by multiphoton absorption appears to be involved.