Electronic quenching and vibrational relaxation of no A2Σ(υ′=1 and υ′=0) by collisions with H 2O

Abstract

Temporally-resolved measurements of laser-induced flourescence from the A 2Σ state of nitric oxide in a series of low-pressure (19, 38, and 76 torr), stoichiometric H 2/O 2/Ar flames were used to obtain electronic quenching and vibrational energy-transfer rates. Using a three-level rate-equation system to model the evolution of the flourescence signal from the directly excited A 2Σ(υ′=1) state and the collisionally-populated A 2Σ(υ′=0) state, we have determined the electronic quenching cross sections for the υ′=1 (36±2 å 2) and υ′=0 (35 ± 3 å 2) levels, as well as the vibrational energy transfer (υ′=1–0) cross section (1.8 ± 0.4 å 2) for NO due to collisions with H 2O at 1340 K. With the temperature lowered from 1340 to 1050 K, the electronic quenching cross sections remain nearly constant while the vibrational energy transfer cross section increased to 3.2±0.5 å.