A theoretical investigation of spectroscopy properties and transition properties of TlBr cation.

The potential energy curves, dipole moments and transition dipole moments of the 14 Λ-S states and 30 Ω states of TlBr cation were performed using the multi-reference configuration interaction method. The Davidson correction and spin-orbit coupling effects were also considered. The spectroscopic properties and transition properties of TlBr cation were reported at the first time. The results show that the XΠ is the ground state and the AΣ is the first excited state, which are both weakly bound states. 14 Λ-S states are all electronically bound except for the 2Π state, which is repulsive. The phenomenon of avoided crossing in the Ω states occurs in the energy region between 30,000 and 50,000 cm. The Franck-Condon factors, radiative lifetimes and emission coefficients between the [Formula: see text] and [Formula: see text] transitions are both calculated. The results indicated that the radiative lifetimes of the [Formula: see text] and [Formula: see text] states are too large to laser cooling TlBr cation, laser cooling of TlBr cation is not feasible. These results provide a theoretical basis to explore the spectroscopic properties of TlBr cation.