The self-relaxation of vibrationally excited fluorosulphate radicals

Abstract The vibrational relaxation of ground state FSO 3 radicals in self-collisions has been studied by using ArF laser photolysis of F 2 S 2 O 6 FSO 3 N 2 (or He) equilibrium mixtures to generate the radicals and time-resolved absorption detection to monitor the decay of the populations. The self-relaxation rate constant for the ensemble of vibrationally excited FSO 3 was found to be (4.2 ± 0.4) × 10 9 M −1 s −1 over the temperature range 379–406 K. Near-resonant intermolecular vibrational-to-vibrational energy transfer pathways may play a dominant role. The rate constant for the quenching by the F 2 C 2 O 6 collision partner, (4.0 ± 0.4) × 10 8 M −1 s −1 , has been determined at 295 K for the fast component of the decay. This value is 4.2 times greater than that determined previously for the slow component.