Low temperature vibrational relaxation of OD in the A2Σ, state

Abstract

The vibrational relaxation of the A 2Σ state of OD has been studied in the low translational temperature environment of an argon free-jet (Ttrans near 5 K). Using laser induced fluorescence (LIF), the absolute vibrational relaxation rate coefficients were measured for OD A2Σ (ν′) to be 7.1 ± 2.6 × 10−11, 5.9 ± 1.4 × 10−11, and 2.7 ± 1.1 × 10−11 cm3 s−1 for the ν = 3, 2 and 1 states, respectively. State-to-state relaxation rate coefficients were also obtained for the ν= 1, Ń = 1 level going to ν= 0, Ń levels in the A2Σ manifold. The rotational relaxation rate coefficient for ν= 1, Ń= 1 in the A state of OD was found to be 9.6 ± 1.0 × 10−11cm3s−1. These values are consistent with values measured for OH A2Σ, and the total loss rates are near the capture rate coefficient value. The vibrational relaxation rate coefficients kν appear to be governed by the vibrational energy of the molecule rather then by interaction with nearby dissociative states such as the a4Σ state. The relative Einstein A factors for the A2σ (ν = 3) state of OD were determined and compared with the available calculated value.