Efficient vibrational relaxation of O2(X 3Σ −g, ν = 8) by collisions with CF4

Abstract

A laser flash photolysis–laser-induced fluorescence (LIF) technique has been employed to study the relaxation kinetics of vibrationally excited O₂(X ³Σ⁻_g). The time-resolved LIF excited B ³Σ⁻_u–X ³Σ⁻_g system has been recorded and analyzed by the integrated-profiles method. The rate coefficient for vibrational relaxation of O₂(X ³Σ⁻_g, ν = 8) by collisions with CF₄, [1.4 ± 0.3(2σ)] × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹, indicates that CF₄ is an efficient relaxant of O₂(X ³Σ⁻_g) and that the propensity rule for O₂ relaxation suggested by Mack et al. (J. A. Mack, K. Mikulecky and A. M. Wodtke, J. Chem. Phys., 1996, 105, 4105) has been observed experimentally.