Explicitly correlated configuration interaction investigation on low-lying states of SiO⁺ and SiO

SiO⁺ and SiO, which play vital roles in astrophysics and astrochemistry, have long attracted considerable attention. However, accurate information about excited states of SiO⁺ is still limited. In this work, the structures of 14 Λ-S states and 30Ω states of SiO⁺ are computed with explicitly correlated configuration interaction method. On the basis of the calculated potential energy curves of those Λ-S states and Ω states, the spectroscopic constants of bound states are evaluated, which are in good agreement with the latest experimental results. The predissociation mechanism of B²Σ⁺ state is illuminated with the aid of spin-orbit coupling matrix elements. On the basis of the calculated potential energy curves and transition dipole moments, the radiative lifetime for each of low-lying vibrational states B²Σ⁺ and A²Π is estimated. The laser cooling scheme of SiO⁺ is proposed by employing B²Σ⁺-X²Σ⁺ transition. Finally, the vertical ionization energy values from SiO (X¹Σ⁺) to ionic states:SiO⁺, X²Σ⁺, B²Σ⁺, and A²Π are calculated, which agree well with experimental measurements.