Vibrational energy transfer in ethylene and ethylene–rare-gas mixtures

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Abstract
Vibrational energy transfer in ethylene and ethylene–rare‐gas mixtures has been investigated. The ν11 (CH2 stretching) mode of ethylene has been excited by the pulses of an optical parametric oscillator with a wavelength of 3.3 μm. Fluorescence from the ν7 (CH2 wagging) mode at 10.5 μm has been detected. The resulting ν7 activation rate for pure ethylene is (267±27) ms−1 Torr−1. The ν7 activation rates of mixtures with rare gases are as follows: for He (13.8±2.7) ms−1 Torr−1, for Ne (16.2±4.9) ms−1 Torr−1, for Ar (32.8±2.6) ms−1 Torr−1, for Kr (34.7±12.1) ms−1 Torr−1, and for Xe (41.3±6.2) ms−1 Torr−1. The V–T/R relaxation rate of ν7 determined in our experiments is in good agreement with former measurements. Preliminary results on the fluorescence from the ν12 (CH2 scissors) mode at 6.9 μm show a ν12 deactivation rate of about 120 ms−1 Torr−1. Possible relaxation mechanisms are discussed.