Energy transfer from state-selected photofragments. Electronic quenching of CS(A1Π)v′= 0–5

Abstract

The collisional quenching of CS(A¹Π)_{v′= 0 → 5}, produced through monochromatic photodissociation of CS₂ in the vacuum ultraviolet, has been studied to assess the influence of translation and vibrational state selection on the quenching rates. The relative efficiencies of the quenching gases studied decrease in the order CS₂ > Xe, CO, CO₂≫ N₂, Ar ≫ He. The rate of electronic quenching by CS₂ and Xe is too fast to allow competition from rotational or vibrational relaxation of the CS(A) but rotational (and translational) relaxation does compete in the remaining systems. The quenching cross-sections for CS₂ and Xe fall inversely with the collision velocity but are insensitive to the vibrational state in the range v′= 0 → 5. The results are compared with data for the quenching of CO(A¹Π) and possible quenching mechanisms are discussed.