Dissociation dynamics of FCO and HCO radicals

Abstract

Dissociation energies and barriers to dissociation for XCO→X+CO have been calculated for X̃ 2A′ and à 2π states of FCO and HCO by ab initio molecular orbital methods. At the PUMP4//UMP2/6-311G* level, D○298 (F-CO)=22.3 kcal mol−1 and ΔH298=24.2 kcal mol−1 for dissociation of ground-state FCO; these values are much higher than the corresponding bond energy and activation enthalpy for HCO dissociation. Calculated RRKM rate constants suggests that the lifetime of FCO under stratospheric conditions is sufficient to allow bimolecular reactions to compete with dissociation. Reaction with O2 may provide an in situ source of stratospheric CO2.