The IR multiphoton decomposition of CF₃I. The effect of inert and reactive gases

Abstract

The multiphoton decomposition of CF31 with a pulsed C02 laser has been studied at incident fluences of 0.6 and 1.2 J/cm2. The effect of pressure on the reaction probability for dissociation of CF3I was measured in the presence of added isobutane, Ar and C02. In the experiments with isobutane, the CF3 radicals generated by the decomposition of excited CF3I react to yield CF3H in competition with the recombination to C2F6. The laser absorption cross section was also measured as a function of fluence at a pressure of 0.1 torr of CF31 and with 0.5-2.0 ton-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 CF31 with the bath molecules. An energy dependent value of ( A E ) d produces the best fit to the experimental data. Integration of the rate equations to account for the fractional product yield, [CF3I]/[C2F6], allowed for the calculation of the specific rate constant for hydrogen abstraction from isobutane by CF3 radicals. The value obtained is dependent on the total pressure and higher than expected at room temperature. From these results, a n effective temperature for the reaction mixture was calculated.

Collisional Deactivation of CDCl3 Excited with a TEA CO2 Laser

“…The average excitation energy of CDCl 3 at both fluences and with varying pressures of Ar, represented by the average number of photons absorbed per molecule, 〈 n 〉, is displayed in Figure . As expected for a small molecule such as CDCl 3 , 〈 n 〉 increases with the pressure of added inert gas up to a fluence dependent limiting value at pressures above ∼40 Torr, due to collisional relaxation of the rotational and anharmonic bottlenecks to absorption. , …”

“…As expected for a small molecule such as CDCl 3 , 〈n〉 increases with the pressure of added inert gas up to a fluence dependent limiting value at pressures above ∼40 Torr, due to collisional relaxation of the rotational and anharmonic bottlenecks to absorption. 1,15 The processes undergone by a CDCl 3 molecule irradiated by a CO 2 laser in the presence of Ar, as deactivating gas, can be represented by the following scheme:…”