Conversion electron Mössbauer spectroscopy of 197Au and its first applications

Abstract

This paper describes the technique of measuring Mössbauer spectra of the 77.35 keV γ-rays of 197Au in very thin gold absorbers, by detecting resonant reemission of low-energy electrons at liquid helium temperature with a channel electron multiplier. The technique is best applicable to specimens of about 10–100 μg Au/cm 2, which is up to two orders of magnitude thinner than required for measurements in transmission mode. The sensitivity limits of the applicability of this technique have been examined. Using strong 197Pt sources in a compact scattering geometry, we were able to obtain the spectra of gold absorbers even as thin as 5 μg/cm 2. Measurements of very thin films of pure gold and gold alloys, as well as the spectra of laser and ion beam-modified surfaces in a sub-μm range of depth are presented as the examples.