Photoionization of Excited State 3d¹⁰4p ²P_1/2 of Cu

The calculation of energy level structures is still a challenge for atomic Cu. In the present work, based on the multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) methods, three large-scale correlation models have been used to calculate the energies and wavefunctions of the singly excited state 3d¹⁰4p ²P_1/2, the doubly excited states 3d⁹4s(³D)5s ⁴D_3/2,1/2, 3d⁹4s(³D)5s ²D_3/2, 3d⁹4s(¹D)5s ²D_3/2 and the ionic state 3d^{10 1}S₀. The results show that the calculated level structures of copper are very sensitive to the choice of finite configuration space. All of the energy differences are less than the existing experimental results by about -0.4 eV between the doubly excited states 3d⁹4s(³D)5s ⁴D_3/2,1/2, 3d⁹4s(³D)5s ²D_3/2, 3d⁹4s(¹D)5s ²D_3/2 and the ionic state 3d^{10 1}S₀ with the singly excited state 3d¹⁰4p ²P_1/2, but the calculated resonant electron energies agree well with the experimental results. In addition, according to the radiative and nonradiative transition matrix elements, the Fano parameters q have been calculated for the doubly excited states. Then, the total photoionization cross sections of singly excited state 3d¹⁰4p ²P_1/2 of copper is obtained, where the interference effects can be considered between direct photoionization and photoexcitation autoionization. The resonances 3d⁹4s(³D)5s ⁴D_3/2,1/2, 3d⁹4s(³D)5s ²D_3/2, 3d⁹4s(¹D)5s ²D_3/2 have obvious asymmetrical Fano profiles, which indicates that the interference between photoionization and photoexcitation autoionization has an extremely important influence on the photoionization cross sections near the doubly excited resonances.