Electronic transitions of cobalt monoboride

Electronic transition spectrum of cobalt monoboride (CoB) in the visible region between 495 and 560 nm has been observed and analyzed using laser-induced fluorescence spectroscopy. CoB molecule was produced by the reaction of laser-ablated cobalt atom and diborane (B 2H 6) seeded in argon. Fifteen vibrational bands with resolved rotational structure have been recorded, which included transitions of both Co 10B and Co 11B isotopic species. Our analysis showed that the observed transition bands are ΔΩ=0 transitions with Ω″ = 2 and Ω″ = 3 lower states. Four transition systems have been assigned, namely, the [18.1] 3Π 2-X 3Δ 2, the [18.3]φ 3φ 3-X 3Δ 3, the [18.6]3-X 3Δ 3, and the [19.0]2-X 3Δ 2 systems. The bond length, r o, of the X 3Δ 3 state of CoB is determined to be 1.705 Å. The observed rotational lines showed unresolved hyperfine structure arising from the nuclei, which conforms to the Hunds case (a β) coupling scheme. This work represents the first experimental investigation of the CoB spectrum. © 2011 American Institute of Physics.published_or_final_versio