Vibrational Relaxation in Polyatomic Gas (Methane)

A method to obtain an expression of the intermolecular potential including internal coordinates is proposed. The potential is assumed to be the sum of interatomic ones. The calculation is carried out for CH 4 –CH 4 interaction and the vibrational relaxation times for ν 4 , ν 2 and ν 1 have been calculated. It is shown that ν 4 relaxation time corresponds to the value obtained by Eucken and Aybar and is the decisive one in the supersonic dispersion in accord with their experiment.