Symmetry-resolved measurements of the core-excitedCS2molecule

Abstract

Core-excited states of the ${\mathrm{CS}}_2$ molecule have been studied in high-resolution angular-resolved experiment. The total ion yield and the angular resolved electron-ion coincidence (PEPICO) spectra of the $\mathrm{S}\mathrm{}\left(2p\right)\mathrm{}$ and $\mathrm{C}\mathrm{}\left(1s\right)\mathrm{}$ excited molecule have been measured. Bending vibrations are excited at the $\mathrm{S}{(2p}^{-1}){\pi }_J^{*}$ state, while the linear geometry is preserved at the $\mathrm{S}{(2p}^{-1}){\sigma }_J^{*}$ state and at the $\mathrm{S}{(2p}^{-1})nl$ Rydberg states. The occurrence of strong vibrational coupling is observed at the $\mathrm{S}\mathrm{}\left(2p\right)\mathrm{}$ excited Rydberg states, which gives rise to excitations of asymmetric stretching modes. Additionally, we show that transitions to the valence $\mathrm{S}{(2p}^{-1}){\pi }_J^{*}$ and $\mathrm{S}{(2p}^{-1}){\sigma }_J^{*}$ states exhibit a strong atomic character, while transitions to the Rydberg states are of molecular type. At the carbon edge the measurements reveal excitations of the nonzero symmetric stretching vibrations at the $\mathrm{C}{(1s}^{-1}){\pi }^{*}$ and the Rydberg levels. Above the $\mathrm{C}{(1s}^{-1})$ threshold doubly excited states have been observed and their assignment is proposed.