Spin-forbidden electronic transition properties of MgO

Abstract

The spin-forbidden transitions of MgO are very important to the photodissociation dynamics and chemical reaction dynamics, which are frequently occurred in the interstellar space. In this work, the internally contracted multireference configuration interaction (icMRCI) method with the Davidson correction is used to compute the adiabatic potential energy curves (PECs) of eight Λ-S electronic states of MgO. Through considering the spin-orbit coupling (SOC) effect, the PECs of six splitting electronic states and the spin-forbidden transition dipole moments (TDMs) between the six lowest lying Ω states are also calculated. Using the calculated PECs and TDMs, the adiabatic transition parameters, including the Franck-Condon factors (FCFs) and radiative lifetimes for spin-forbidden transitions (a3Π0+,1−X1Σ0++ and A1Π1−a3Π0+,1), are determined. As for the a3Π0+,1−X1Σ0++transition, the radiative lifetimes are shorter, which means the stronger emission could occur. The FCFs for the A1Π1−a3Π0+,1 transition are highly diagonal and the values are greater than 0.94, but with large vibrational radiative lifetimes. The results obtained in this work are consistent with experimental ones and can be used to further investigate the mechanism of chemical reaction dynamics.