Theoretical modelling and experimental studies of the multi-quantum vibration exchange in vibrationally excited CO molecules

Studies of the vibration-vibration (VV) exchange in CO molecules excited up to vibration quantum numbers, nu = 20 have been performed both theoretical ly and experimentally. A new kinetic model which takes into account the mul ti-quantum VV exchange in the temperature range T = 100-300 K is described for the first time. A description is given of the experimental methodology allowing for studies of the effects of the relaxation of the vibrational di stribution after a sudden disturbance. The disturbance of the vibrational d istribution is produced by a Q-switched short pulse of single line radiatio n in fundamental band. The relaxation is studied by measuring the laser pul se energy of the second pulse initiated by resonator Q-switching produced w ith a variables time delay relative to the first pulse. A set of kinetic ra te constants accepted in the model for various gas temperatures, vibration level numbers and number of exchanged vibration quanta from 1 to 4 is prese nted. The good agreement between the experimental data and the results of t he advanced theory is the first direct evidence in support of the multi-qua ntum exchange model.