Relaxation of active levels in CO laser due to CO*-CN collisions

An experimental check was made of the postulated mechanism of relaxation of vibrationally excited CO* molecules in collisions with CN radicals. Calculations and experimental results indicated that the formation of the CN radicals in electronically excited states was due to collisions with the vibrationally excited CO* molecules. The cross section of this process was 10^–13–10^–14 cm². The populations of the CN (B²∑, A²∏) states were determined as a function of the discharge current, pressure and composition of laser mixtures, cooling conditions, and occurrence of stimulated emission. In mixtures free of oxygen, the rate of relaxation of the vibrational energy of the CO molecules colliding with CN was fairly high and comparable with the rate of relaxation as a result of spontaneous infrared emission and it should be allowed for in theoretical calculations. In mixtures containing oxygen, the influence of CN on the relaxation of the active levels was negligible because of a strong reduction in the concentration of CN in the ground state. The influence of CN on the populations of the active vibrational levels was also considered.