Time resolved study of rotational energy transfer in A 2Σ+(ν′ = 0) state of OH in a flame by laser induced fluorescence

Abstract

Time resolved study of rotational transfer in the A ²Σ⁺(ν′ = 0) state of OH in a flame is performed by analyzing the fluorescence spectra scanned at different delays after the short exciting laser pulse. The conditions under which a three level model apply are discussed. Then comparison between this kinetic model and experiment provides direct total transfer rate out of the J′ = 7 1/2 excited level: The specific transfer cross sections derived are 70 Ų for N₂ and 18 Ų for Ar. The fluorescence spectra show a strong propensity for spin conservation upon rotational transfer. As the delay increases, the rotational population distribution among the upper state tends to a Boltzmann distribution.