Mössbauer Effect in Two Excited States of a Rotational Band inYb171

Mössbauer Measurements on the ratio of the quadrupole splitting of the first and second excited states in ${\mathrm{Yb}}^{171}$ show that the intrinsic quadrupole moment is constant within the experimental error of 3% for the first two members of the $K=\frac{1}{2}$ rotational band. The width of the resonance line gives a lifetime for the 75.9-keV state in ${\mathrm{Yb}}^{171}$ of $\tau =(1.5\mathrm{}\pm 0.3)$ nsec. This is 40% shorter than the electronically measured value. The electric field gradient for the $C_2$ site in ${\mathrm{Yb}}_2$ ${\mathrm{O}}_3$ is found to be (2.83±0.06)×${10}^{18}$ V/${\mathrm{cm}}^2$.