Optimization of conditions for selective dissociation of trifluorobromomethane molecules in carbon isotope separation

An experimental study was made of the characteristics of multiphoton dissociation of CF₃Br molecules when ¹³CF₃Br is excited under collisional conditions. For the first time, measurements were made of the selectivity of multiphoton excitation of a natural mixture of ¹²C and ¹³C isotopes, and its dependences on the excitation frequency and buffer pressure were determined. It was observed that the selectivity of excitation of ¹³CF₃Br molecules in the low-frequency wing of the ν₁ band is governed by the absorption at the 3ν₃ overtone and its thermal bands, and the dissociation selectivity is governed exclusively by the conditions of excitation of the molecules in the ν₁ band. The optimum regime for selective dissociation of CF₃Br in terms of energy consumption matched to the parameters of existing CO₂ lasers was determined. At a radiation energy density of 2.6 J/cm² the energy consumption is ~260 eV per ¹³C atom. This regime may be used as the first stage in laser enrichment of carbon isotopes.