Mössbauer Effect in the 121.2-keV Transition inSm147

The Mössbauer effect has been observed in the decay of the ${\frac{5}{2}}^{-}$ 121.2-keV state of ${\mathrm{Sm}}^{147}$. Sources were ${\mathrm{Pm}}^{147}$ in a mixed Pm-Sm oxide matrix and ${\mathrm{Eu}}^{147}$ in ${\mathrm{Sm}}_2$ ${\mathrm{O}}_3$. Both types of sources gave single Lorentzian lines when used with an ${\mathrm{Sm}}_2$ ${\mathrm{O}}_3$ absorber. The ${\mathrm{Eu}}^{147}$ source was used with a samarium iron garnet absorber to obtain the excited-state nuclear moments. The magnetic dipole moment is found to be $-0.445\mathrm{}\pm 0.025{\mu }_N$. Using an atomic-beam measurement of the ground-state quadrupole splitting, an estimate of -0.31 ± 0.12 b is obtained for the excited-state quadrupole moment. Three light rare-earth odd-neutron nuclei have now been studied by the Mössbauer effect: ${\mathrm{Nd}}^{145}$, ${\mathrm{Sm}}^{147}$, and ${\mathrm{Sm}}^{149}$. The $g$ factors for the low-lying levels of these nuclei cluster about -0.22. The present theoretical models are not particularly successful in accounting for the magnetic moments.