Investigation of the CS22+ dication using threshold photoelectrons coincidence spectroscopy

Abstract A threshold photoelectrons coincidence (TPEsCO) spectrum of CS 2 has been recorded in the 26.8–29.8 eV range with a resolution of 40 meV using a synchrotron radiation source. The X 3 Σ − g , a 1 Δ g , b 1 Σ + g and c 1 Σ − u states of CS 2 2+ have been observed in the spectrum and their double ionisation potentials determined. Vibrational structure of these states was also observed for the first time and comparison with recent theoretical results allowed its tentative assignment to vibrational progressions associated with the symmetric stretching mode. The experimental spectrum also revealed important contributions from indirect photoionisation processes in the formation of CS 2 2+ from the neutral CS 2 molecule.