The IR multiphoton decomposition of CF 3 I. The effect of inert and reactive gases

The multiphoton decomposition of CF 3 I with a pulsed CO 2 laser has been studied at incident fluences of 0.6 and 1.2 J/cm 2 . The effect of pressure on the reaction probability for dissociation of CF 3 I was measured in the presence of added isobutane, Ar and CO 2 . In the experiments with isobutane, the CF 3 radicals generated by the decomposition of excited CF 3 I react to yield CF 3 H in competition with the recombination to C 2 F 6 . The laser absorption cross section was also measured as a function of fluence at a pressure of 0.1 torr of CF 3 I and with 0.5–2.0 torr of added isobutane. The experimental results were modeled with a master equation in order to obtain information on the energy transferred by collisions of excited CF 3 I with the bath molecules. An energy dependent value of 〈Δ E 〉 d produces the best fit to the experimental data. Integration of the rate equations to account for the fractional product yield, [CF 3 I]/[C 2 F 6 ], allowed for the calculation of the specific rate constant for hydrogen abstraction from isobutane by CF 3 radicals. The value obtained is dependent on the total pressure and higher than expected at room temperature. From these results, an effective temperature for the reaction mixture was calculated. © 1994 John Wiley & Sons, Inc.