Carbon Monoxide Vibrational Relaxation in Mixtures with Helium, Neon, and Krypton

Abstract

The collisional relaxation of CO vibrational excitation for He, Ne, and Kr as collision partners has been determined by observation of infrared emission behind incident shock waves. The data are fit by these equations: CO–He, ln_e(pτ) = 87T^—⅓—19.1 for 580<T°Ke(pτ) = 142T^—⅓—21.1 for 1400<T°Ke(pτ) = 187T^—⅓—22.3 for 2100<T°Kp atm, where τ is in sec and T in Kelvin degrees. Extrapolation of these data and the CO–H₂ data previously available to room temperature yields values that correspond well with those from the quenching of CO vibrational fluorescence for the CO–H₂ and CO–He cases. There is wide disagreement in the CO–Ne case. This is traced to an improper extrapolation in the quenching method for obtaining the Ne datum. The collision mass dependence of vibrational relaxation for constant oscillator frequency is briefly discussed.