Laser-induced emission of SO in matrices: The c̃ ¹Σ ^-→ã ¹Δ and the Ã′ ³Δ→X̃ ³Σ^- transitions

The laser-induced emission was observed during irradiation of samples containing Cl₂SO, SO₂, or OCS/NO₂ in a Ne matrix by a KrF excimer laser at 248 nm. Two progressions are assigned to SO. The progression in the range 353-601 nm is assigned to the Ã′ ³Δ→X̃ ³Σ^- transition with ν₀₀ = 29 494 ± 5 cm^-1, ω″ _e = 1151 ± 2 cm^-1 and ω″ _ex″_e = 6.2 ± 0.2 cm^-1, whereas the progression in the range 491-822 nm is assigned to the c̃ ¹Σ→ã ¹Δ transition with ν₀₀ = 22564 ± 5 cm^-1, ω″_e = 1115 ± 3 cm^-1, and ω″_ex″ _e = 6.8 ± 0.2 cm-1. In an Ar matrix, the corresponding progressions of SO in various matrix sites were also observed. The thermoluminescence lines observed previously from solid Ar correspond to the phonon wings of an unstable site before annealing. A third progression that was also observed is assigned to the emission from the v′ = 1 level of the c̃ ¹Σ^- state; its separation by 670 cm ^-1 from the main c̃→ã progression agrees with the predicted ω′_e of the c̃ ¹Σ ^- state.