Transition properties of the spin- forbidden a4Π-X2Π systems in the NO, PO and PS molecules

Abstract

The potential energy curves (PECs) for six low-lying states corresponding to the first dissociation limit (4Su+3Pg) of the NO, PO, and PS molecules are calculated by the multireference configuration interaction (MRCI) method. The X2Π -a4Π band is the focus of this work. By introducing the spin-orbit coupling (SOC) with Breit-Pauli operator via state-interacting technique, the PECs and wavefunctions compositions of Ω states are obtained. Based on the Λ-S states composition of the corresponding Ω states and the calculated electric-dipole transition moments between Λ-S state, we present intensity of the spin-forbidden quartet-doublet bands. Spectroscopic constants for all sub-bands of the a24Π3/2, a34Π1/2, a44Π1/2→X12Π1/2 and a14Π5/2, a24Π3/2, a34Π1/2, a44Π1/2→X22Π3/2 systems of the NO, PO, and PS are estimated. A set of transition parameters of these sub-bands are given. The present results are supposed to provide a significant supplement for the spin-forbidden a4Π→X2Π band origins of the astrophysically important NO, PO, and PS molecules.