The electronic structure of HgCl and HgBr

A b initio configuration interaction calculations using effective core potentials are presented for the low-lying electronic states of HgCl and HgBr. The B→X laser wavelengths and vibrational constants for the B and X states are in very good agreement with experiment. The equilibrium separations (Re) for the B and X states in HgCl (HgBr) are found to be 2.42 (2.61 Å) and 2.93 Å (3.04 Å), respectively. The purely electronic radiative lifetime for the B state in HgCl (HgBr) is calculated to be 27.5 ns (27.6 ns). The mixing of ionic and covalent character in the X and B states and its effect on the R dependence of the transition moment is discussed briefly. Finally, the possibility of self-absorption is considered.