A ROTATIONAL AND HYPERFINE ANALYSIS OF THE [14.0](2)SIGMA(-X(2)SIGMA(+) BAND SYSTEM OF COBALT MONOCARBIDE())

The cobalt monocarbide molecule has been produced by laser ablation of a cobalt rod in the presence of 1.5% methanol in a helium carrier gas . The mixture was expanded into a vacuum, yielding a free jet with T-r ot similar to 30 K. Low resolution laser-induced fluorescence studies showed the [14.0](2) Sigma(+) - X(2) Sigma(+) band system as a long vi brational progression between 500 and 720 nm. Several vibrational band s were analyzed at high resolution; least squares fitting of the data led to the determination of rotational and hyperfine constants for bot h states. The X(2) Sigma(+) state is best described by a Hund's case ( b(beta S)) coupling scheme, while the [14.0](2) Sigma(+) state conform s to case (b(beta J)). Analysis of the hyperfine parameters indicates that the X(2) Sigma(+) state arises from a valence (8 sigma)(2)(3 pi)( 4)(1 delta)(4)(9 sigma)(1) electronic configuration and that the [14.0 ](2) Sigma(+) state originates from a (8 sigma)(1)(3 pi)(4)(1 delta)(4 )(9 sigma)(2) configuration. The vibrational levels of the [14.0](2) S igma(+) state appear to be perturbed by other nearby states; this is r eflected in unusual distortions in the spin-rotation parameters from o ne vibrational level to the next. The effects of the perturbations are also observed in the sign and magnitude of the hyperfine dipolar inte raction parameters of the [14.0](2) Sigma(+) state, and effects are al so observed on the Fermi contact and electric quadrupolar parameters. (C) 1997 Academic Press, Inc.