Relativistic effects in many electron hyperfine structure III. Relativistic dipole and quadrupole interaction in europium and remeasurement of the nuclear magnetic dipole moments of 151Eu and 153Eu

The nuclear magnetic dipole moments of 151Eu and 153Eu have been re-measured. The revised values (corrected for diamagnetic shielding) are: μ(151Eu) = 3.4630 ± 0-0006 n.m., μ(153Eu) = 1.5292 ± 0-0008 n.m. The ratio of the moments is μ(151Eu)/μ(153Eu) = 2.26505 ±0.00042. These results were obtained by the method of triple resonance in an atomic beam. The hyperfine structure anomaly in the ground state of the europium atom is zero within limits of error. In this special circumstance it is shown that part of the nuclear magnetic dipole interaction is explained by relativistic effects. The quadrupole interaction is treated by the same theory, and good agreement with experiment is obtained, but high precision is not claimed for the theoretical result. This theory is based on a new relativistic calculation involving the use of an effective operator acting between non-relativistic states.