Spectroscopic investigations of transition properties for the electronic states of PN+ correlating to two lowest dissociation limits

Abstract

The PN+ cation is regarded as a candidate of ions which may exist in the interstellar medium. Accurate transition properties are desired to identify the spectra from astronomical observation. However, transition data of PN+ are relatively limited. In this work, the state-of-the-art ab initio calculations are carried out to investigate the low-lying electronic states of PN+ correlating to two lowest dissociation limits, its transition properties and its spin-orbit couplings. For the X2Σ+ and A2Π states, the calculated spectroscopic constants agree well with previous experimental data. For the other electronic states, the accuracy of the spectroscopic parameters is also ensured by comparing with previous theoretical results. Then, transition probabilities of dipole allowed transition systems are calculated. The radiative lifetimes of vibrational levels for the A2Π, 14Π, 14Δ, 14Σ−, and 24Π states are also evaluated. Such transition data can be used in the identification of PN+ in the laboratory or the interstellar space. Finally, the predissociation of 14Σ− (υ' = 1)→16Σ+, 14Σ− (υ' = 15)→16Π and 14Δ (υ'= 19)→16Π are analyzed with the help of spin-orbit coupling integrals.