The comparative analysis of the processes responsible for dissociation of m
olecular iodine in the oxygen-iodine medium is made. The rate of relaxation
of vibrationally excited oxygen in the O-2 - I-2 - H2O medium is shown to
be limited by the VV energy exchange between oxygen and water molecules, an
d the fraction of vibrationally excited O-2 (v = 1) in the active medium of
the oxygen-iodine laser can reach several tens of percent. It is noted tha
t the VV exchange in O-2(1 Delta, v = 1)+I(P-2(3/2))<->O-2((3)Sigma1,v = 1)
+I(P-2(1/2)) reaction may be of considerable importance in the kinetics of
formation of the active medium in the oxygen-iodine laser.