Nuclear quadrupole coupling constants of rovibrational levels of all isotopic species of BH + in their X 2Σ + and B′ 2Σ + states

Abstract

The 11B, 10B, and 2H quadrupole coupling constants of rovibrational levels in the X 2Σ + and B′ 2Σ + states of 11B 2H +, 10B 2H +, 11B 1H +, and 10B 1H + are calculated from molecular wavefunctions which explicitly describe nuclear motion. Except for the boron coupling in the B′ 2Σ + state, the vibrational dependence of the nuclear quadrupole coupling constants is found to be significant for all the isotopic species studied. The rotational dependence of the 2H nuclear coupling constants is predicted to be unimportant. The changes with rotational excitation of the boron coupling constants are significant only for higher vibrational levels in the ground electronic state. The 11B and 10B coupling is found to be relatively very strong for all isotopic variants, the 2H coupling in 10B 2H + and 11B 2H + is, especially in the B′ 2Σ + state, rather weak. The quadrupole hyperfine structure of 10B 2H + and 11B 2H + is essentially determined by relatively very strong boron coupling, the energy levels being perturbed by the deuteron coupling. In the B′ 2Σ + state the perturbing effect is found to be negligible, in the low-lying rovibrational levels of the ground electronic state the corresponding splitting is found to be quite sizeable.