Energy-Crossing and Its Effect on Lifetime of the 4s24p 2P_3/2 Level for Highly Charged Ga-Like Ions

The multi-configuration Dirac–Fock method is employed to calculate the energy levels and transition probabilities for the electric dipole allowed (E1) and forbidden (M1, E2) lines for the 4s24p, 4s4p2 and 4s24d configurations of highly charged Ga-like ions from Z=68–95. The lifetimes of the 4s24p 2P_3/2 level of the ground configuration are also derived. Based on our calculations, it is found that the energy level of the 4s24p 2P_3/2 is higher than that of the 4s4p24P_1/2 for the high-Z Ga-like ions with Z≥74, so as to generate an energy crossing at Z=74. The effect of the energy crossing is important to the calculation of the 4s24p 2P_3/2 level lifetime for Ga-like ions with Z≥74.