Solid-State and Nuclear Results from a Measurement of the Pressure Dependence of the Energy of the Resonance Gamma Ray ofAu197

Abstract

Metallic gold has been subjected to a sequence of pressures in the range from 0 to 70.6 kbar at a temperature of 4.2°K, and the change of the energy of the ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ resonance $\gamma$ ray with pressure has been measured. The measurements were made by the Mössbauer method. The result for $\frac{d{E}_{\gamma }}{\mathrm{dP}}$ is in good agreement with an earlier prediction for this quantity based on a correlation of the Mössbauer isomer shift with residual electrical resistance for a series of dilute gold alloys. We have used the Wigner-Seitz approximation to describe the gold $6s$ band, and this wave function has been calculated in a relativistic Hartree approximation. Within this treatment we find that the gold nucleus increases in size when excited, with $\frac{\Delta r}{r}\cong +1.5\mathrm{}\times {10}^{-4\mathrm{}}$. A brief comment is made on the bearing which these results have on the charge and screening of gold atoms in dilute gold alloys.