Isotopically selective multiphoton decomposition of CF 3Br and CF 3I: separation of selective and non-selective product sources

Abstract

The decomposition yield and the isotopic selectivity of carbon-13 production in the infrared multiphoton decomposition of CF 3Br and CF 3I have been determined from the observed product C 2F 6. These two observables have been studied in focussed beam geometry as a function of accumulated number of pulses from the CO 2 laser, pressure of absorber and energy per pulse. The isotopic selectivity is independent of fluence but decreases with pressure, mostly due to equilibrium thermal processes. The amount of C 2F 6 formed increases as a function of (pressure) 2 and of (pulse energy) 2. This is explained in terms of a simple diffusional quenching model where energy pooling is the dominant reaction leading to dissociation.