Quenching of FSO3(B̃2E) generated by 193 nm photodissociation of FSO2OF and F2S2O6

Abstract The collisional relaxation of electronically excited FSO 3 radicals, generated by laser photodissociation of FSO 2 OF and F 2 S 2 O 6 at 193 nm, was studied by examination of the absorption rise profiles due to the appearance of ground state vibrationally excited FSO 3 radicals. Room temperature quenching rate constants for collision partners He, N 2 , O 2 , Cl 2 , CO 2 , CF 4 , FSO 2 OF and F 2 S 2 O 6 were measured (in units of 10 9 dm 3 mol −1 s −1 ); they are 2.0 ± 0.2, 1.4 ± 0.2, 1.6 ± 0.2, 3.6 ± 0.4, 3.2 ± 0.4, 2.7 ± 0.4, 11 ± 1 and 20 ± 2 respectively. Both precursors employed yield electronically excited radicals with essentially the same kinetic properties and a radiative lifetime (4.2 ± 0.5 μs) which agrees very well with that evaluated from the integrated oscillator strength for the B 2 E state of the FSO 3 radical. The experimental quenching cross-sections are well correlated with the well depth of the FSO 3 (B 2 E)-quencher interaction.