Resonant two-photon ionization spectroscopy of jet-cooled OsN: 520-418 nm

The optical transitions of supersonically cooled OsN have been investigated in the range from 19 200 to 23 900 cm^-1 using resonant two-photon ionization spectroscopy. More than 20 vibronic bands were observed, 17 of which were rotationally resolved and analyzed. The ground state is confirmed to be ²∆_5/2, deriving from the 1σ² 2σ² 1π⁴ 1δ³ 3σ² electronic configuration. The X ²∆_5/2 ground state rotational constant for ¹⁹²Os¹⁴N was found to be B₀ = 0.491921(34) cm^-1, giving r₀ = 1.62042(6) Å (1σ error limits). The observed bands were grouped into three band systems with Ω^' = 7/2 and four with Ω^' = 3/2, corresponding to the three ²Φ_7/2 and four ²Π_3/2 states expected from the 1σ² 2σ² 1π⁴ 1δ³ 3σ¹ 2π¹ and 1σ² 2σ² 1π⁴ 1δ² 3σ² 2π¹ electronic configurations. In addition, two interacting upper states with Ω^' = 5/2 were observed, one of which is thought to correspond to a 1σ² 2σ² 1π³ 1δ³ 3σ² 2π¹, ²∆_5/2 state. Spectroscopic constants are reported for all of the observed states, and comparisons to related molecules are made. The ionization energy of OsN is estimated as IE(OsN) = 8.80 ± 0.06 eV.