NMR and spin echo measurements were performed on dilute samples of ${}_{}{}^{187}{}_{}{}^{}\mathrm{Os}$ and ${}_{}{}^{189}{}_{}{}^{}\mathrm{Os}$ in Fe. The magnetic hyperfine splitting frequencies ${\nu }_{\mathit{M}}$=|g${\mathrm{\mu }}_{\mathit{N}}$${\mathrm{B}}_{\mathrm{HF}}^{\left(\mathrm{eff}\right)}$/h| at 4.2 K were determined to be 111.17(1) and 371.00(5) MHz for ${}_{}{}^{187}{}_{}{}^{}\mathit{Fe}$ and ${}_{}{}^{189}{}_{}{}^{}\mathit{Fe}$, respectively. Taking into account the known magnetic moments, the hyperfine anomaly is deduced to be ${}_{}{}^{187}{}_{}{}^{}\mathrm{\Delta }_{\mathrm{Fe}}^{189}{}_{}{}^{}$ = +0.0195(2), which is of opposite sign and much smaller than expected theoretically. © 1996 The American Physical Society.

• Received 28 May 1996

DOI:https://doi.org/10.1103/PhysRevC.54.2310