THERMAL LENSING STUDY ON THE KINETICS OF IR MULTIPHOTON DISSOCIATION

Thermal lensing (TL) signals from CCIF2CHCl2 gas undergoing IR multiph oton dissociation (IRMPD) have been observed. The rising rate of the T L signals increases with increasing laser energy fluence above the rea ction threshold fluence, while it is constant below the threshold flue nce. An explanation is given by comparing the result with a kinetic mo del, in which the rate of the vibrational deactivation of both the rea ctant and product molecules and a unimolecular reaction rate of the vi brationally excited molecules are taken into account. The applicabilit y of the TL method to investigations of the IRMPD is mentioned.