Spectroscopy of the 1S0-1D2 clock transition in 176Lu+

High-precision spectroscopy of the S-1(0)-D-1(2) clock transition of Lu-176(+) is reported. Measurements are performed with Hertz level precision with the accuracy of the hyperfine-averaged frequency limited by the calibration of an active hydrogen maser to the SI definition of the second via a GPS link. The measurements also provide accurate determination of the D-1(2) hyperfine structure. Hyperfine structure constants associated with the magnetic octupole and electric hexadecapole moments of the nucleus are considered, which includes a derivation of correction terms from third-order perturbation theory.