Spectroscopy of CrF: Rotational analysis of the B-6 Pi-X(6)Sigma(+) band system in the 1.2 mu m region

The B (6) Pi-X (6) Sigma(+) band system of the CrF radical has been recorded in emission with FTS techniques in the region between 6965 and 9240 cm(-1), using a resolution of 0.025 cm(-1). A rotational analysis including the (0,0), (1,1), (1,0), (0,1) and (1,2) bands of this system has been carried out, and a set of molecular parameters has been derived for the B (6) Pi state. The present analysis has also resulted in substantially better determined values for the lambda and gamma parameters of the X (6) Sigma(+) ground state. An improved set of molecular parameters has been derived for the previously analyzed, heavily perturbed A (6) Sigma(+) state. The present analysis gives strong support for the interpretation that the local perturbations in the upsilon = 0-3 levels of A (6) Sigma(+) are due to interactions with the vibrational levels upsilon = 3-6 of the B (6) Pi state. Earlier suggestions involving a low-lying (4) Pi state as the dominating perturber of the A (6) Sigma(+) state must now be considered as erroneous. A previously suggested interpretation of the 7400 cm(-1) band as being possibly due to a quartet transition has also been shown to be in error. The derived first order spin-orbit parameter value of B (6) Pi [A = 47.0382(18) cm(-1)] and the equilibrium bond distances of X (6) Sigma(+) [1.7839 Angstrom], A (6) Sigma(+) [1.8919 Angstrom], and B (6) Pi [1.8277 Angstrom] have been discussed, and it has been proposed that the 9 sigma (Cr-4s-4p) molecular orbital of CrF is slightly bonding, while 4 pi (Cr-3d pi) is nonbonding and 10 sigma (Cr-3d sigma)antibonding. (C) 1996 American Institute of Physics.