A theoretical study on the ionization of H2S with analysis of vibrational structure of the photoelectron spectra Original Research Article

Ab initio calculations were performed to study the molecular structures and the vibrational levels of the low-lying ionic states (2B1, 2A1 and 2B2) of hydrogen sulphide. The equilibrium molecular structure and the vibrational analysis of these states are presented. The normal vibrational calculations at the RHF level and more extensive calculations at the SDCI level using the explicit vibrational Hamiltonians were used for the vibrational analysis. The theoretical ionization intensity curves including the vibrational structures of these ionic states are also presented and compared with the photoelectron spectrum. The results show that the global shape of the potential energy surface has to be taken into consideration in order to analyze the 2A1 and 2B2 states. A new assignment of the photoelectron spectra of H2S is proposed.