Analysis of autoionizing Rydberg series Cu I 3d 9 4snl with the multichannel quantum defect theory

Using atomic beam technique, a combination of collisional and laser excitation, and photoion detection, autoionizing Cu I states in the region of the ionization limits Cu II 3d ⁹ 4s(^3,1 D) were investigated. In spite of the complicated structure of the signals due to the four different ionization limits³ D ₃,³ D ₂,³ D ₁ and¹ D ₂ and the large number of possible (LSJ)-states, which can be reached by this experimental technique, the majority of the signals could be attributed to definite Rydberg series 3d ⁹ 4s(³ D ₃,³ D ₂,³ D ₁,¹ D ₂)nl (LSJ). Perturbations were analyzed by the three- and four-channel quantum defect theory and by Hartree-Fock calculations. General formulas for the calculation of the photoionization cross section by the four-channel quantum defect theory in the case of two closed and two open channels are given.