A high resolution spectroscopic study of rhodium monochloride

Rhodium monochloride has been observed and characterized spectroscopically for the first time. The RhCl molecules were produced in a laser vaporization molecular beam source by the reaction of a laser vaporized rhodium plasma with CCl4 doped in helium, and laser-induced fluorescence and dispersed fluorescence were used to study 15 of the strongest bands spanning the 535-415 nm region. Twelve of these bands were studied at high resolution using a cw ring dye laser. Two low-lying states separated by 140 cm−1 have been observed. The ground state has Ω = 2 and is attributed to a 3Πi state resulting from a δ4π3σ1 electronic configuration. The other low-lying state has Ω = 3 and is attributed to a 3Δi state resulting from a δ3π4σ1 electronic configuration. Excited states with Ω values ranging from 1 to 4 have been observed. Dispersed fluorescence from these excited levels has been used to identify a large number of low-lying electronic states within an energy range of 5200 cm−1 and has also been used to determine a ground state vibrational frequency of ∼348 cm−1. Λ-doublings have been observed in all the transitions studied at high resolution.