MULTIREFERENCE-CONFIGURATION INTERACTION (MR-CI) CALCULATIONS ON HS2+ AND EXPERIMENTAL-OBSERVATION VIA ELECTRON-IMPACT IONIZATION OF H2S

The stability of the HS2+ dication is investigated both theoretically and experimentally. The theoretical analysis involves complete active-space self-consistent field (CASSCF) and multi-configuration reference-configuration interaction (MRCI) theory. A metastable 2P{cyrillic} ground state is found with a calculated barrier to dissociation of 1.52 eV. No other metastable states for energies up to 10eV above the ground state are found. In conjunction with the theoretical results, electron impact ionization of H2S is able to generate the HS2+ dication, demonstrating that the species exists on a time scale longer than 10 μs. The appearance potential for HS2+ from H2S is 42.3 ± 1.0 eV. Evidence is also presented for the electron impact production of S2+, H2S2+ and H3S2+. © 1990.