Collisional electronic quenching of OH A 2Σ (v′=0) measured at high temperature in a shock tube

Rate coefficients are reported for electronic quenching of OH A 2Σ v′=0 by N2, O2, CO, CO2, NO, Ar, Kr, and Xe measured at high temperatures behind reproducible shock waves. The cross section for quenching by Ar was found to be less than 0.06 Å2. The cross sections for quenching by N2 and Kr were found to be 0.5 and 1.0 Å2, respectively. The cross sections for the remaining species were found to be of order gas kinetic. For all of the species the cross sections were found to be very weak functions of temperature from 1900 to 2300 K. The measured cross sections are compared with previous measurements at lower temperatures. The observed variation with species and with temperature is observed to be consistent with a charge-transfer model for the process.