SCCS^- radical: Renner-Teller effect and spin-orbit coupling in the X ²Π<inf>u</inf> electronic state

Abstract

SCCS- was detected by laser-induced fluorescence spectroscopy in 2003 (M. Nakajima, Y. Yoneda, Y. Sumiyoshi, T. Nagata, Y. Endo, J. Chem. Phys. 119 (2003) 7805) and its spectrum was analyzed and the results presented together with ab initio calculations data. Symmetrical stretching vibrations were assigned in both the ground X 2Πu and the first excited A 2Πg electronic states, but no data about spin-orbit splitting and bending vibrational modes were given. In the present work, the vibronic levels in the ground electronic state of SCCS- were calculated by means of a model developed by Perić and coworkers for the treatment of the Renner-Teller effect in any-atomic linear species in its variational form (M. Mitić, R. Ranković, M. Milovanović, S. Jerosimić, M. Perić, Chem. Phys. 464 (2016) 55) using the ab initio multi-reference configuration interaction calculations for obtaining potential energy curves in the Born-Oppenheimer approximation. Additionally, the spin-orbit splitting in the ground state was investigated taking into account the interaction with the first excited state, and the energies obtained from combined treatment of vibronic and spin-orbit interactions in the ground state are reported. Finally, based on the present results, several assignments of unidentified bands reported by Nakajima et al. are proposed.