The Spectrum of CuO: Low Lying Electronic States Observed by Laser Induced Fluorescence

The spectrum of gas phase CuO in the red and near infra-red wavelength region is studied by the laser induced fluorescence technique. Three new low lying electronic states, αΣ, γ2Πi and δ2 Σ, with the approximate T0 values αΣ 15 424 cm-1 γ2Π1/2 15 470 cm-1 γ2Π3/2 15 166 cm-1 δ2 Σ 12 986 cm-1 are reported. The multiplicity of the αΣ is uncertain. It is tentatively considered to be a quartet. The vibrational constants of the δ2 Σ state are ωe ~ 661 cm-1 and ωexe ~ 5.7 cm-1. Earlier results on the spectrum of CuO are reviewed. Intensity anomalies, originating from interference between groups of states, are discussed.