Mössbauer-Effect inYb171

Abstract

Recoil-free nuclear resonance absorption of the 67-keV $\gamma$ ray has been observed. ${\mathrm{Tm}}^{171}$ in the form of the sesquioxide was used as a source, and ${\mathrm{Yb}}_2$ ${\mathrm{O}}_3$ and Yb metal as absorbers. Source and absorber were held at the same temperatures of 50, 4.2, and 1.6°K. Due to the field gradient present in the oxide crystal, the 67-keV state ($I=\frac{3}{2}$) splits into two substates with a separation of 2.4×${10}^{-6\mathrm{}}$ eV extrapolated to 0°K. The Yb metal forms a cubic crystal lattice and shows no splitting. The observed linewidth gives a lower limit of 7×${10}^{-10\mathrm{}}$ sec for the lifetime of the 67-keV state. Comparison with previous data of other authors on the hyperfine splitting of the 84-keV level in ${\mathrm{Yb}}^{170}$ in ${\mathrm{Yb}}_2$ ${\mathrm{O}}_3$ gives a value of 1.04 for the ratio $\frac{Q_0\mathrm{}\left(171\right)\mathrm{}}{Q_0\mathrm{}\left(170\right)\mathrm{}}$ of the intrinsic quadrupole moments, which agrees well with the values obtained by Coulomb excitation.