Electronic transitions of S2- and S3- in neon matrixes

The sulfur Sn- n = 2, 3 anions produced in a hot cathode discharge ion source were mass-selected and embedded in a neon matrix at 6 K. A long progression with the excitation of up to 12 vibrational quanta is observed in the A 2Πu ← X 2Πg electronic spectrum of S2-, with the onset at 467.1 nm. The inferred spectroscopic constants in the A 2Πu state are: ν0−0 = 21,407 ± 4 cm−1, ω0′=328.4±1 cm−1, ω0′x0′=2.4±0.1 cm−1. The electronic spectrum of S3- in a neon matrix exhibits a rich vibrational structure with a bimodal intensity distribution. This results from the overlap of two electronic transitions, C∼2A2←X∼2B1 and (D∼ or E∼) ← X∼2B1, with origins at 701.3 and 619.1 nm. The frequencies (cm−1) of the totally symmetric modes ν1 and ν2 are 466, 184 in the C∼2A2 and 446, 177 in the (D∼ or E∼) states.