A theoretical study of the dissociative recombination of SH+ with electrons through the 2Π states of SH

Bimolecular reactions of S2+ with Ar, H2 and N2: reactivity and dynamics

The reactivity, energetics and dynamics of bimolecular reactions between S²⁺ and three neutral species (Ar, H₂ and N₂) have been studied using a position-sensitive coincidence methodology at centre-of-mass collision energies below 6 eV. This is the first study of bimolecular reactions involving S²⁺, a species detected in planetary ionospheres, the interstellar medium, and in anthropogenic manufacturing processes. The reactant dication beam employed consists predominantly of S²⁺ in the ground ³P state, but some excited states are also present. Most of the observed reactions involve the ground state of S²⁺, but the dissociative electron transfer reactions appear to exclusively involve excited states of this atomic dication. We observe exclusively single electron-transfer between S²⁺ and Ar, a process which exhibits strong forward scatting typical of the Landau-Zener style dynamics observed for other dicationic electron transfer reactions. Following collisions between S²⁺ + H₂, non-dissociative and dissociative single electron-transfer reactions were detected. The dynamics here show evidence for the formation of a long-lived collision complex, [SH₂]²⁺, in the dissociative single electron-transfer channel. The formation of SH⁺ was not observed. In contrast, the collisions of S²⁺ + N₂ result in the formation of SN⁺ + N⁺ in addition to the products of single electron-transfer reactions.

Diabatic potential energy curves for the $$^4{\Pi} $$ states of SH

We present a diabatic representation of the potential energy curves (PECs) for the $$^4{{\Pi}} $$ 4 Π states of $$\mathrm {SH}$$ SH . Multireference, configuration interaction (MRCI) calculations were used to determine high-accuracy adiabatic PECs of both $$\mathrm {SH}$$ SH and $${\mathrm {SH}}^+$$ SH + from which the diabatic representation is constructed for $$\mathrm {SH}$$ SH . The adiabatic PECs exhibit many avoided crossings due to strong Rydberg-valence mixing. We employ the block diagonalization method, an orthonormal rotation of the adiabatic Hamiltonian, to disentangle the valence autoionizing and Rydberg $$^4\Pi $$ 4 Π states of $$\mathrm {SH}$$ SH by constructing a diabatic Hamiltonian. The diagonal elements of the diabatic Hamiltonian matrix at each nuclear geometry render the diabatic PECs and the off-diagonal elements are related to the state-to-state coupling. Care is taken to assure smooth variation and consistency of chemically significant molecular orbitals across the entire geometry domain.

Theoretical study of the low-lying electronic states, including the spin-orbit interactions, of the sulfur monochloride cation

High-level ab initio computations have been performed on the experimentally unknown species SCl⁺. The low-lying Λ-S electronic states correlated to the first and the second dissociation channels as well as their corresponding Ω states have been investigated by the icMRCI+Q methodology employing basis sets up to quintuple-ζ quality. Information about potential energy curves, electron configurations, spectroscopic constants, dipole moments and transition properties are derived and discussed. The results for SCl⁺ represent an improvement over our previous theoretical descriptions for the ground state. In addition, several low-lying excited states that have not been accessed experimentally and theoretically are also been well characterized in this work. The accuracy of our predictions for SCl⁺ are verified by comparisons of spectroscopic constants and vibrational levels between our accompany SCl computations and those reported in literatures for the neutral species. The feasibility of performing laser cooling of SCl⁺ has also been discussed and the photoelectron spectrum of SCl⁺(X³Σ^-) + e ← SCl(X²Π) is simulated.