Search for Anomalous Narrowing of the Mössbauer Transition ofAu197

Mössbauer linewidth measurements of the 77.34-keV $\gamma$ ray of ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ are reported as a function of absorber thickness for Au metal foils and for AuCN and KAu${\mathrm{}\left(\mathrm{CN}\right)\mathrm{}}_2$ powders dispersed in inert boron nitride. The linewidths extrapolated to zero absorber thickness for these materials agree with each other, with previous Mössbauer results for Au, and with values deduced from electronic lifetime measurements to well within 3%. The recently reported anomalous ∼ 13% line narrowing in AuCN and KAu${\mathrm{}\left(\mathrm{CN}\right)\mathrm{}}_2$ is therefore not confirmed.