The vibrational and hyperfine spectroscopy toward laser cooling ⁸⁷Sr³⁵Cl

We theoretically investigate the possibility of laser cooling ⁸⁷Sr³⁵Cl molecule in accordance with vibrational and hyperfine spectroscopy. The potential energy curves and dipole moment of the X²Σ⁺_1/2, A²Π_1/2,_3/2 and B²Σ⁺ states are calculated using ab initio method and the spectroscopic parameters are in good agreement with the experimental data. On account of the accurate potential energy curves and the transition dipole moment, the Franck - Condon factors and radiative lifetimes are predicted. Comparing the conditions of laser cooling candidate molecules, the A²Π _1/2 ↔ X²Σ⁺_1/2 transition is selected as the laser cooling cycle system. In order to obtain an approximately closed cooling cycle system, we employed matrix element algorithm to calculated the hyperfine spectroscopy and branching ratios of the ⁸⁷Sr³⁵Cl molecule. Furthermore, an electro-optical modulator (EOM) is designed including six hyperfine levels of the ground state X²Σ⁺_1/2 (v = 0, N = 1).