ANALYSIS OF THE ${^{2}}\Sigma^{+} - X^{2}\Sigma^{+}$ BAND SYSTEM OF COBALT CARBIDE.

Abstract

A pulsed molecular beam apparatus has been used to obtain high resolution laser-induced fluorescence spectra of the cobalt carbide molecule. The molecules were made by reaction of laser-abalted cobalt atoms with 1% methanol in He under supersonic-jet cooled conditions. The $^{2}\Sigma^{+} - X^{2}\Sigma^{+}$ band system displays a long vibrational progression extending from the red into the green region of the visible spectrum. Analysis of the excited state progression $(up to \nu^{\prime}, \nu^{\prime\prime} = 7, 0)$ has resulted in a set of accurate molecular constants, including hyperfine interaction parameters, for the ground and excited states. The ground $^{2}\Sigma^{+}$ state conforms to the rather rare Hund's case ($b_{ss}$) coupling model, while the upper ${^{2}}\Sigma^{+}$ state seems to be characteristic of case $(b_{ss})$ coupling.