High precision investigations of the hyperfine structure of metastable levels in a chromium atom

A series of precise measurements of the hyperfine structure (hfs) of nine metastable levels in a chromium atom 53Cr has been performed. For eight levels the hfs has been investigated with the method of laser induced fluorescence (LIF) on an atomic beam, and for the lowest-lying metastable level 3d54s 5S2 a still more precise method of laser-rf double resonance on an atomic beam (ABMR-LIRF) has been applied. A semi-empirical analysis of the fine and the hyperfine structure of the chromium atom, including many-body interaction effects, has been carried out in order to determine the value of the nuclear electric quadrupole moment, which amounts to Q = −0.22(1) barn.