Collisional Transition Probabilities for Rotational Levels of CN ( B 2Σ+)

Rotational relaxation of CN (B 2Σ+) formed by interaction of metastable argon atoms with CNBr was studied. The CN (B 2Σ+) initially is formed only in a few perturbed rotational levels for some vibrational states. Transfer out of the initially formed rotational levels via collision with argon took place with about the same rate for all rotational levels studied, although the magnitude of the rotational level spacings differed for the various cases that were investigated. Transition probability models were developed to simulate the observed pressure dependence of the spectrum. The best fit was obtained with a model having down transitions given by Pi → j = (0.2|i −j| + 0.05) (2j + 1)/(2i + 1). For all models, it was essential to include a large probability of multiquantum (|i−j| > 4) transitions in order to fit the data.