High precision hyperfine structure measurements in185Re and187Re

The hyperfine structure of the atomic levels 5d ⁵ 6s ^{2 6} S _5/2 and⁴ P _5/2 in¹⁸⁵Re and¹⁸⁷Re has been studied with high precision by atomic-beam magnetic-resonance. Additional measurements were performed in the 5d ⁵ 6s ^{2 4} G _5/2 and 5d ⁶ 6s ⁶ D _9/2 states of¹⁸⁷Re. For the interpretation of the results eigenvectors in intermediate coupling have been derived by a least squares fit of all known levels of the configurations (5d+6s)⁷. The ratioB(¹⁸⁵Re)/B(¹⁸⁷Re) is the same for the⁶ S _5/2 and the⁴ P _5/2 state within the error limits of 6 parts in 10⁵. Combining the present results with the known hyperfine structure data of¹⁸⁶Re and¹⁸⁸Re we find the magnetic-dipole hyperfine anomalies for the isotopic series^185?188Re.