Measurement of the Natural Lifetimes and Quenching Rate Constants of OH(2Σ+, v = 0,1) and OD(2Σ+, v = 0,1) Radicals

Abstract

The lifetimes of OH(²Σ⁺) and OD(²Σ⁺) radicals were measured by using pulse-photolysis of water and methanol in the vacuum-uv for the production of the electronically excited radicals. From the fluorescence decay measurements the natural lifetimes, as well as the quenching rate constants for several added gases such as H₂O, CH₃OH, H₂, N₂, Ar, and He were determined. In particular, the natural lifetime of OH (²Σ⁺, v = 0), τ = (1.00 ± 0.06) · 10^-6 s, was corrected for rotation-vibration as well as for rotation-electronic interactions resulting in a lifetime of (0.83 ± 0.08) · 10^-6 s for the rotationless state. A lifetime of (0.82 ± 0.08) · 10^-6 s was derived for the rotationless state of OD(²Σ⁺,v = 0).