Vibrational relaxation of S2(a1Δg) by collisions with SF6 and CF4

Abstract

Irradiation of the pulsed laser light at 248nm to the gaseous mixture of OCS and He generated vibrationally excited S2(a1Δg,v=2-4) by the S(1D)+OCS reaction. A single vibrational level of S2(a1Δg) was detected with laser-induced fluorescence (LIF) via the f1Δu-a1Δg transition. The rate coefficients for energy transfer from vibrational levels v=2 and 3 of S2(a1Δg) to SF6 and CF4 have been determined from the time-resolved LIF intensities recorded at varying pressures of SF6 and CF4. The reduced probability of energy transfer per collision derived from the rate coefficients enabled us to identify the ν4 mode of SF6 and CF4 as the energy-accepting vibration.