Quenching and vibrational energy transfer in the B 2Π state of the NS molecule

Abstract

Quenching and vibrational energy transfer in the B2Π state of the NS free radical have been studied using temporally and spectrally resolved laser-induced fluorescence in a low-pressure discharge flow reactor. The collision partners were He, Ar, H2, N2, O2, SF6, CO2, and N2O. Total removal cross sections show an oscillatory behavior with v′ in the range of unperturbed levels, v′=4–7, for all colliders studied save O2 where a nearly monotonic increase is seen. Vibrational transfer occurs for H2 and the polyatomics; the rates vary little with v′. Δv=2 transfer occurs with the polyatomic colliders for v′=5. Fluorescence decay traces from the perturbed v′=3 and 8 levels differ from the unperturbed levels and from each other. v′=3 is perturbed by quartets and shows ‘‘gateway’’ level behavior whereas v′=8 is perturbed by a doublet and shows efficient interelectronic transfer for all rotational levels.