Vibrational Relaxation of CO₂ (00⁰1) in H₂ and D₂ below Room Temperature

Abstract

The deactivation rates of CO₂ (00⁰1) in H₂ and D₂ were determined in the temperature range of 300∼150 K from the observed decay of the 4.3 μm fluorescence which was induced by the HBr laser pulse, The rate in H₂ below room temperature is slightly smaller than that extrapolated form the high temperature data assuming the temperature dependence of the Landau-Teller type. Contrary to this, a decreasing temperature dependence was found for the rate in D₂ at lower temperatures. The calculation of energy transfer probabilities based on the long range multipole interaction between CO₂ (00⁰1) and H₂ suggests a contribution of the vibration-to-rotation energy transfer: CO₂ (00⁰1)+H₂ (ν=0, J=2 or 3)→ CO₂ (10⁰0 or 02⁰0)+H₂ (ν=0, J=4 or 5).