Structures of molecular anion: Photoelectron spectroscopy and theoretical calculations

An intense beam of the dimer anion of CS2 was prepared by a pulsed-discharge nozzle, which enabled the measurement of the previously-reported 2.7-eV photoelectron band of C 2 S 4 - with higher spectral resolution at 355 nm. This measurement has revealed that the band consists of a vibrational progression with an average spacing of 0.13 ± 0.01 eV, indicating a bound electronic property of the residual C2S4 neutral. With the aid of molecular orbital calculations, the observed progression has been assigned to the transition from C 2 S 4 - (2B1) to the vibrationally-excited states of C2S4(1A1), both possessing cyclic C2v structures.