Theoretical study on spectroscopic properties of 8?-Sand 23? states for BH molecule

In this work, the potential energy curves of eight low electronic states (X1S+, a3P, A1P, b3S-, 23P, 13S+, 15S-,and 15P) and twenty-three W states of BH molecule, and the transition dipole moments among the ,, a3P1, a3P2, and A1P1 states are calculated by using the internally contracted multireference configurationinteraction (icMRCI) method. In order to obtain the accurate potential energy curve, the errors caused bysingle and double electron excitation, core-valence correlation effects, relativistic effects and basis set truncationare corrected. The spectral and transition data of BH molecule are in good agreement with the availabletheoretical and experimental data. The calculation results show that the A1P1(u ' = 0-2, J ' = 1, +) ->(u ''= 0-2, J '' = 1, -) transition has large Einstein A-coefficient, weighted absorption oscillator strength, and highlydiagonal vibrational branching ratio Ru ' u '', and the excited state A1P1(u ' = 0, 1) have short spontaneousradiation lifetimes. Moreover, the effects of and a3P1 states on A1P1(u ' = 0) <->(u '' = 0) cycletransition can be ignored. Therefore, according to the A1P1(u '= 0-1, J ' = 1, +) <->(u ''= 0-3, J '' = 1, -)cycle transition, we propose to apply one main cooling laser (l00 = 432.45 nm) and two repumping lasers (l10 =479.67 nm and l21 = 481.40 nm) to laser cooling BH molecules, and evaluation of the cooling effect.

Automated summary

In this study, the potential energy curves and transition dipole moments of various electronic states of BH molecule were calculated using the icMRCI method. The obtained spectral and transition data are in good agreement with existing theoretical and experimental data. The results show that a specific transition has large Einstein A-coefficient and oscillator strength, and certain excited states have short spontaneous radiation lifetimes. Based on these findings, a laser cooling scheme for BH molecules is proposed.