Astrochemical Significance of the P + SO Reaction: Spectroscopic Characterization of SPO, PSO, and SOP Isomers

The doublet and quartet potential energy surfaces for the P + SO → PO + S reaction are explored using the highly accurate explicit correlation multireference configuration interaction method, and the reaction is found to be thermodynamically favorable, with an exothermicity value of 70.5 kJ mol⁻¹. The electronic structure, spectra, and bond dissociation energies of the intermediates involved in the reaction, such as SPO, PSO, and SOP, are calculated using high-level quantum chemistry methods. An explanation of the nondetection of the diatomic SP is proposed. At pressures relevant to astrochemistry, the reaction is overwhelmingly bimolecular, with a predicted rate coefficient of 2.1 × 10⁻¹⁰ (T/300)^−0.23 cm³ molecule⁻¹ s⁻¹. The results from this study are expected to aid in the spectroscopic detection of these new species in the laboratory and the interstellar medium.