PERTURBATIONS IN THE CN(B2-SIGMA-X2-SIGMA+) TAIL BAND SYSTEM .4. THE B2-SIGMA+SIMILAR-TO-A2-PI-I PERTURBATIONS IN THE UPSILON-B=11, 14-16, 18 AND 19 LEVELS()

Highly rotationally excited levels of the CN(B2SIGMA+-X2SIGMA+) 11-11, 14-14, 16-14, 18-17 and 19-18 bands were observed with high resolutio n by use of the reaction of argon flowing afterglow with BrCN. The obs erved transitions were analyzed in terms of the B2SIGMA+ approximately A2PI(i) perturbations. The molecular constants for the A2PI(i) v = 26 , 30, 33, 36 and 38 levels, which perturb the B2SIGMA+, v = 11, 14, 16 , 18 and 19 levels, respectively, and the interaction constants were d etermined. The anomalously large spin splittings reported for the CN(B 2SIGMA+-X2SIGMA+) 15-15 band were attributed to the perturbation betwe en the B2SIGMA+, v = 15 and A2PI(i), v = 31 levels. The molecular cons tants for the A2PI(i) state determined in the present study were fitte d by polynomial expansions together with those reported previously, an d the Rydberg-Klein-Rees potential for the A2PI(i) state was determine d up to v = 38.