Hyperfine Structure of the Spectrum of Cu I and Test of the Hyperfine Structure Formulas

Abstract

The hyperfine structure (hfs) of the levels 3d⁹4s^{2 2}D_5⁄2 and ²D_3⁄2 was measured and compared with the usual hfs formulas for d-electrons, and a discrepancy between theory and experiment was found. This can be phenomenologically interpreted by assuming that the values of ⟨1⁄r³⟩ are different for 3d_5⁄2- and 3d_3⁄2-electrons, namely ⟨1⁄r³⟩=7.4 and 8.0 for 3d_5⁄2- and 3d_4⁄2-electrons respectively, where r is measured in unit of hydrogen atom radius.