Mössbauer effect of the 13.3-keV transition in Ge73

Experiments are described which have allowed observation of the recoilless resonance effect of the 13.3-keV transition (τ=4.3 μsec) in Ge73. The methods and precautions in such experiments are detailed. The resonance effect is shown to be sensitive to lattice damage by proton irradiation and to lattice strain induced by Si-Ge epitaxial mismatch. The effect is observed in microcrystalline powders as well as in elemental single crystals. An upper limit for the transition of 15% is established for dispersion effects introduced by possible interference between internal conversion and photoeffect processes. The sharpest Ge73 resonance observed thus far has an uncorrected resonant depth of 2.37(14)% and an experimental full width at half maximum linewidth of 13.8 (1.3) μm/sec. This is the narrowest Mössbauer resonance ever observed at room temperature.