Nuclear Properties and Magnetic Hyperfine Interaction ofOs189

Mössbauer absorption of the 69.6-keV $\gamma$ rays from ${\mathrm{Os}}^{189}$ has been studied in various absorbers at 4.2°K. The following quantities have been determined: the half-life of the 69.6-keV state, $t_{\frac{1}{2}}\ge 1.8\pm 0.2$ nsec; the magnetic moment of the 69.6-keV state, $\mu \mathrm{}\left(69.6\right)=(0.988\mathrm{}\pm 0.010){\mu }_N$; the mixing ratio of the 69.6-keV transition, $\delta =\frac{〈\parallel E2\mathrm{}\parallel 〉}{〈\parallel M1\mathrm{}\parallel 〉}=+0.71\mathrm{}\pm 0.08$; and the hyperfine field at the Os nuclei dilutely dissolved in Fe, $H_{\mathrm{hf}}=1100\mathrm{}\pm 20$ kOe. The results pertaining to the nucleus are compared with calculations in terms of the rotational model.