Theoretical study of level structure and transitions of configurations 3d94s2 3d94s4p, 3d94p2 for Nb XIII

Fine-structure energy levels of two-electron excitation configurations 3d94s2, 3d94s4p, 3d94p2 are calculated by Hartree-Fock method, which includes the configuration interaction, relativistic correction and approximate Breit correction, for copper-like Nb XIII. More accurate levels are obtained by the least-square-fit technique. The wavelengths and transition probabilities of 3d94s4p-3d104s, 3d94s2-3d104p, 3d94p2-3d104p, 3d94s4p-3d94s2 transition array are obtained, and some unknown results are predicted. Computing research shows that the 40.92 nm line should belong to 3d94s(1D)4p2F7/2-3d9(2D)4s2 2D5/2 transition, but not to the 3d94s(1D)4p4D7/2-3d9(2D)4s2 2D5/2 transition, and the upper term level should be 2F7/2, but not 4D7/2.