Photodissociation of CFCl3 at 193 nm investigated by photofragment translational spectroscopy

The collisionless photodissociation of CFCl 3 at 193 nm has been studied with the method of crossed laser and molecular beams. The primary dissociation is shown to produce exclusively the fragment pairs CFCl 2 + Cl with a non-thermal translational energy distribution. The average kinetic energy of 32 kcal/mol corresponds to 42% of the available energy and implies an average internal energy of CFCl 2 of 43 kcal/mol. From the recoil anisotropy parameter β = +0.74 ± 0.15 the photoexcitation is inferred to proceed via an E ← A 1 transition polarized perpendicular to the C–F bond. At higher laser fluence a fraction of the nascent CFCl 2 radicals absorbs a further photon and dissociates into CFCl + Cl; the cross section for this secondary process is estimated to be approximately twice as large as that of the primary photodissociation.