Energy transfer in the ground state of OH: Measurements of OH(υ=8,10,11) removal

Abstract

OH collisional removal rate constants for υ=8, 10, and 11 with O2, N2, CO2, N2O, and He are measured. Vibrationally excited OH molecules in υ=5, 7, and 8 are prepared from the reaction of atomic hydrogen with ozone, and selectively excited to υ=8, 10, and 11, respectively, with a pulsed infrared laser via direct overtone excitation. Subsequent collisional deactivation of these laser-populated levels is probed as a function of collider gas partial pressure using a time-delayed, pulsed ultraviolet laser resonant with OH(B 2Σ+−X 2Π) transitions. Fluorescence from OH(B 2Σ+−A 2Σ+) is detected. These results complete a series of removal rate constant measurements for OH(X 2Π) up to υ=12. Resonance enhancement effects in vibration-to-vibration energy transfer for CO2 and N2O factor significantly in the vibrational-level-dependent rate constants.