Infrared Multiphoton Dissociation of ${CF_2}HCl$ : Laser Fluence Dependence and the Effect of Intermolecular Collisions

The effect of intermolecular collisions in the infrared multiphoton dissociation (IRMPD) of difluorochloromethane was investigated using He, Ar, and as buffer gases. The reaction probability for IRMPD of difluorochloromethane was measured as a function of laser fluence and the buffer gas pressure under unfocused beam geometry. It was observed that the reaction probability was initially enhanced with the increase of buffer gas pressure up to about 20 torr, but showed a decline at higher pressures. The reaction probability increases monotonically with the laser fluence, but the rate of increase diminishes at higher fluences. An attempt was made to simulate the experimental results by the method of energy grained master equation (EGME). From the parameters that fit the experimental data, the average energy loss per collision, $_d$, was estimated for the He, Ar, and buffer gases.