Dynamics of Vibrational Relaxation of Multiphoton Excited SF₆ Molecules in Gaseous Mixtures Containing Ozone and Inert Gases (He, Ar, Kr)

Abstract

SF₆ at pressure of 0.6 Torr in gas mixtures with ozone (0 ÷ 5 Torr) and inert gases: He, Ar, Kr (0 ÷ 5 Torr) was vibrationally excited with and IR pulsed radiation of CO₂ TEA laser at 10P20 laser line (F= 0.6 J/cm²). The vibrational energy transfer from multiphoton excited (MPE) molecules SF₆ to the components of gaseous mixture was probed by UV absorption of ozone at λ = 253.6 nm band. The relaxation process of MPE molecules SF₆ was proposed to occur through parallel V-V' and V-T collisional channels. Based on the kinetic model, collisional rate constants were determined from the time evolution of UV absorption data after laser shot. The obtained values of relaxation rate constants are: KV−VSF6−O3=7.7, 10−13 cm3/s, KV-TSF6−He=3.1 10−13cm3/s, KV−TSF6−Ar=2.3 10−13 cm3/s, KV−TSF6−Kr=7.7 10−14 cm3/s, KV−TSF6−SF6=(4.8÷6.4) 10−13 cm3/s.The observed decay of IR fluorescence from MPE SF₆ molecules at λ=6.3 μm wave number in SF₆-Kr gas mixtures had an exponential time profile with the constant characteristic relaxation time (V-T). The rate of IR fluorescence cluenching allowed us to find an effective V-T relaxation rate constants for collisional partners: KV-TSF6−Ar=7.8​10−14​cm3/s. KT-VSF6−SF6=1.0​10−12​cm3/s.