Characterization of the excited electronic states of the SH radical byab initiomethods

Abstract

Ab initio MRD-CI calculations have been performed for the SH radical in its low-lying valence states as well as vertically for the first Rydberg terms (2π24s, 2π24p and 2π23d). The lowest 1 4,2Σ-, 1 2Δ and 2 2Σ+ states are found to be of valence character in the vertical region, while a Rydberg structure was suggested by an earlier ab initio study. For the bound X 2Π i and A 2Σ+ various molecular constants such as spectroscopic parameters, dipole moments, Franck-Condon factors and spin-orbit constant are reported. The predissociation of A 2Σ+ in its low-vibrational levels observed by Ramsay is confirmed to be caused by the repulsive 1 4,2Σ- states. Furthermore, a complete reassignment of the electronic structure of the experimentally measured Rydberg levels is given: all these states are found to have a 2π24s (B 2Σ- and C 2Δ), 2π23d σ (E 2Σ-) and 2π2 nd σ, n = 3–6 (D, F, G, H 2Δ) electronic configuration respectively. The E 2Σ- and C 2Δ states are classified here for the first time, while the B 2Σ- has be...