Near infrared emission spectra of CoH and CoD

New high resolution emission spectra of CoH and CoD molecules have been recorded in the 640 nm to 3.5 μm region using a Fourier transform spectrometer. The bands were excited in a carbon tube furnace by the reaction of cobalt metal vapor and a mixture of H2 or D2 with He at a temperature of about 2600 °C. Eight bands were observed for the A′3Φ4-X3Φ4 electronic transition of CoD, and five bands for the corresponding transition of CoH. The (0, 0) bands of the A′3Φ3-X3Φ3 system were also recorded for both isotopologues, although one of the parity components in the X3Φ3 sub-state of CoH was found to be perturbed. The A′3Φ3-X3Φ4 transition was also observed in our spectrum of CoH. In addition, a new [13.3]4 electronic state was found by observing [13.3]4-X3Φ3 and [13.3]4-X3Φ4 transitions in the spectrum of CoD. Analysis of the transitions with ΔΩ = 0, ± 1 provided more accurate values of spin-orbit splittings between Ω = 4 and Ω = 3 components. The ground-state data for both molecules were fitted both to band-constant and Dunham-expansion expressions, and a combined-isotopologue analysis of the X3Φ4 spin component was carried out using the data for CoH and CoD. The upper states were represented by term values in these analyses because of perturbations, but estimated band constants for them were obtained in separate fits in which ground-state constants were held fixed.