Collision-Free Lifetimes of SO(B3Σ-, v‘ = 0, 1, and 2) and Vibrational Level Dependence of Deactivation by He

Abstract

Collision-free lifetimes and deactivation rate constants of SO(B3Σ-, v‘ = 0, 1, and 2) by collisions with He have been determined. SO(X3Σ-) was generated in the photolysis of SO2 at 193 nm (ArF laser) and excited to a single rovibrational level of B3Σ- with a pulsed ultraviolet laser. We recorded dispersed fluorescence spectra, and found that 0−12 (350.8 nm), 1−14 (368.5 nm), and 2−17 (401.2 nm) bands are suitable for detecting fluorescence from single vibrational level of interest. Time profiles of wavelength-resolved fluorescence were recorded at various buffer gas pressures (5−165 Torr of He). Deconvolution by the integrated phase plane method derives apparent fluorescence lifetime at a given pressure. Total pressure dependence of fluorescence decay rates leads to collision-free lifetimes and rate constants for deactivation of SO(B3Σ-, v‘ = 0, 1, and 2) by collisions with He. Lifetimes of SO(B3Σ-) have been determined to be (28 ± 2) ns (v‘ = 0), (30 ± 3) ns (v‘ = 1), and (27 ± 4) ns (v‘ = 2). Rate coef...