Measurement of LargeE2Dispersive Interference in the High-ResolutionGe73Mössbauer Transition at Natural Linewidth

The unbroadened Mössbauer resonance from the 13.3-keV level of ${}_{}{}^{73}{}_{}{}^{}\mathrm{Ge}$ is observed. The resonance shows a marked dispersive asymmetry, $2\xi =-9.5\mathrm{}\left(1.9\right)\%$. This is far larger than has been observed for other $E2\mathrm{}$ transitions, but is in agreement with recent calculations of Goldwire and Hannon. The absence of broadening [$2{\Gamma }_{\mathrm{meas}}=6.9\mathrm{}\left(9\right)\mathrm{}$ μm/sec] of this high-resolution ${\frac{5}{2}}^{+}\to {\frac{9}{2}}^{+}$ resonance in a cubic lattice places an upper limit of 28 kHz on possible hexadecapole energy splittings in either nuclear level.