Temperature dependent electronic quenching of OH(A 2Σ+, v′=0) between 230 and 310 K

Abstract

Measurements were made of the temperature dependence of the rate constant for collisional quenching of the v’=0 level of the A ²Σ⁺ electronically excited state of the OH radical. For all quenchers examined (CO₂, H₂, O₂, and N₂), we observed that the thermally averaged cross section σ_Q increased as the temperature is decreased. For N₂, the slowest quencher, σ_Q shows a dramatic increase from 4.0±0.7 Ų at 311±10 K to 7.0±0.6 Ų at 232±5 K. The results of this work and other high temperature (900–1300 K) studies from this laboratory are compared with a description of the collisional encounter involving attractive forces and complex formation.