INFRARED MULTIPHOTON DISSOCIATION OF 2-CHLORO-1,1,1,2-TETRAFLUOROETHANE IN A MOLECULAR-BEAM

Mechanism and dynamics of the infrared multiphoton dissociation of 2-chloro-1, 1,1,2-tetrafluoroethane have been studied using a photofragmentation translational spectroscopy. The molecule dissociates competitively through three-centered elimination of HCl and C-Cl bond rupture. The HCl elimination reaction accounts for 74% of the total primary dissociation yields. The center-of-mass translational energy distribution for the HCl elimination indicates that an exit barrier of several kcal/mol exists along the reaction coordinate on the potential energy surface. The infrared multiphoton dissociation of CF3CF produced by the HCl elimination from CF3CHClF also occurs as a secondary process through its dissociation into two CF2 molecules. The average excitation energy of dissociating CF3CHClF has been determined to be about 20 kcal/mol above the C-Cl dissociation threshold of the molecule by comparing the observed center-of-mass translational energy distribution for the C-Cl bond rupture reaction with that calculated by Rice-Ramsperger-Kassel-Marcus (RRKM) theory.