Spectroscopy of triatomic [Si, P, O] molecules

Abstract

Phosphorus is an element essential to sustaining life, and its compounds are widely involved in the biogeochemical cycles on Earth. Although a handful of phosphorus-bearing species, e.g. PO, have thus far been detected in diatomic form in circumstellar envelopes, their formation processes are still poorly understood. In this study, we examine the structure and spectroscopy of the [Si, O, P] system. Based on high-level ab initio electronic structure calculations with the MRCI + Q and CCSD(T) methods, four isomers could be formed and the most stable form predicted to be bent at all theoretical levels. The doublet and quartet potential energy surfaces (PESs) of P(2D)/P(4S) + SiO(1Σ) reactions are explored, and the spectroscopic parameters of the key isomers involved in the reaction are calculated. The present study highlights the possibility of PO formation via photodissociation of bent-SiOP. The results are expected to aid in the spectroscopic detection of these triatomic phosphorous-bearing species and provide insights into similar reactions of isoelectronic systems.