## The effect of the nuclear electric quadrupole HFI on the total transition rate

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**Figure 1.** The effect of the nuclear electric quadrupole HFI on the total transition rate. Notation A_{{\rm total}}^{\mu + Q} and A_{{\rm total}}^\mu denote the total transition rate of the hyperfine levels of 3d^{9}4s ^{3}D_{3} under the influence of either both the nuclear magnetic dipole and electric quadrupole interaction or only the nuclear magnetic dipole interaction, respectively.

**Abstract**

Based on the multi-configuration Dirac–Hartree–Fock method and using the GRASPVU package, a theoretical investigation was performed to study the lifetimes of hyperfine levels of the first excited level 3d^{9}4s ^{3}D_{3} in Ni-like ions (*Z* = 72–79) for all stable isotopes with nuclear spin. Comparisons between hyperfine-induced electric quadrupole transition rates and the pure magnetic octupole transition rates show that the extra electric quadrupole transition channel caused by the nuclear magnetic dipole and electric quadrupole hyperfine interaction is important for most hyperfine levels in each individual ion. Lifetimes of most hyperfine levels are sensitive to this extra decay channel. Extreme cases are found in ^{181}Ta, ^{185}Re and ^{187}Re, where lifetimes of some hyperfine levels are shortened by more than an order of magnitude.