Theoretical Study on the Electronic Structure and Transition Properties of Low Excited States of SeCl.

For the first time, the spectroscopy and transition properties of SeCl+ are systematically reported. The potential energy curves of 22 Λ - S states and the corresponding 51 Ω states in the first and second dissociation channels of SeCl+ are calculated using the internally contracted multiconfiguration interaction and Davidson correction method. The phenomenon of avoided crossing in Ω states below 30,000 cm-1 is discussed in detail. The spectroscopy constants are obtained by fitting the potential energy curves, and also the Franck-Condon factors and radiation lifetimes of the X3Σ0+- ↔ 21Σ0++ transition are calculated. Between X3Σ0+- and 21Σ0++, the Franck-Condon factors are large, close to 1, but the radiation lifetime is large too. According to the calculation results, it is determined that direct laser cooling of SeCl+ is considered infeasible.