Reactions and quenching of vibrationally excited hydroxyl radicals

Abstract

Rate constants for the deactivation of vibrationally excited hydroxyl radicals by the inert gases Ar, O₂, N₂, H₂, and D₂ have been determined. Additionally the rate constants for the reaction HO(v)+O₃→ products have been measured and found to decrease from 11×10⁻¹² to 3.7×10⁻¹² cm³ molecule⁻¹⋅ sec⁻¹ from v=9 to v=4. Hydroxyl radicals were generated in a large tank at low pressures from the reaction of hydrogen atoms and ozone. The radicals were formed in excited vibrational states (v?9), and the excited radicals, v=4 to 9, were observed by visible light emission from high overtone transitions. Vibrational populations and the rate constants for loss processes were deduced from observations over a wide range of wavelength and pressure fitted to a comprehensive model of the system.