Spin-orbit splitting of the ground state of WO

Abstract

Spin-orbit splitting of the ground electronic state X 3Σ− of the WO molecule has been detected in the single-vibronic-level emission spectra, in which the fluorescence emitted from the R-branch bandheads of excitation bands D′1 − X3Σ−1 (0–0) [Ram et al., J. Mol. Spectrosc.256, 216 (2009)] and [23.3]1 − X3Σ−0+ (0–0) [Zhang et al., J. Mol. Spectrosc.360, 7 (2019)] was dispersed. The emission spectra were assigned with the help of Franck-Condon factors calculation and proved that the two excited states D′1 and [23.3]1 are a common state. Therefore, the separation between the two spin components Ω′′ = 0+ and 1 of the ground electronic state X 3Σ− was determined as 2103.15(2) cm−1. Some previously observed electronic states were reassigned, and a new energy level diagram of WO was constructed.