Measurement of vibrational relaxation times by the spectrophone. Application to CH4, CO2, N2O, COS, NH3 and HCN

Abstract

Various effects giving pressure-dependent phase shifts in the spectrophone have been analyzed, and the results used in studying vibrational relaxation from the higher modes of several gases. The following times, expressed as relaxation times at 1 atm pressure, were required for vibrational energy excited in the modes indicated to transfer to translational energy: CH4, ν3 at 3.3µ, 1.6±0.4 µsec; CO2, ν3 at 4.3 µ, 7.0±0.5 µsec; N2O, ν3 at 4.5 µ, 1.6±0.2 µsec; COS, ν3 at 4.8 µ, 0.7±0.1 µsec; NH3, ν1 at 3.0 µ, <0.1 µsec; HCN, ν3 at 3.0 µ, <0.1 µsec.