Spin and Magnetic Moment ofEu152andEu154by Paramagnetic Resonance

The microwave paramagnetic resonance hyperfine structures of 13-year ${\mathrm{Eu}}^{152}$ and 15-year ${\mathrm{Eu}}^{154}$ have been observed in a sample of ${\mathrm{Eu}}^{2+}$ which was incorporated in a KCl powder. From the number of his lines the spins were found to be $I\left({\mathrm{Eu}}^{152}\right)=3\mathrm{}$ and $I\left({\mathrm{Eu}}^{154}\right)=3\mathrm{}$. Neglecting hfs anomalies, from the ratios of the total hfs splitting these magnetic moment ratios were obtained: $\frac{\left|\mu \right({\mathrm{Eu}}^{154}\left)\right|}{\left|\mu \right({\mathrm{Eu}}^{153}\left)\right|}=1.308\mathrm{}\pm 0.004$, $\frac{\left|\mu \right({\mathrm{Eu}}^{152}\left)\right|}{\left|\mu \right({\mathrm{Eu}}^{151}\left)\right|}=0.5574\mathrm{}\pm 0.006$, $\frac{\left|\mu \right({\mathrm{Eu}}^{151}\left)\right|}{\left|\mu \right({\mathrm{Eu}}^{153}\left)\right|}=2.264\mathrm{}\pm 0.006$. Using $\mu \left({\mathrm{Eu}}^{153}\right)\cong 1.6$ nm, we find $\left|\mu \right({\mathrm{Eu}}^{154}\left)\right|\cong 2.1$ nm and $\left|\mu \right({\mathrm{Eu}}^{152}\left)\right|\cong 2.0$ nm. These results are discussed in relation to the nuclear shell model.