Analysis of Thin Surface Layers by Fe-57 Mössbauer Backscattering Spectrometry

Abstract

Fe‐57 Mössbauer spectra for extremely thin surface layers (600–3000 Å) were obtained by detecting internal conversion electrons emitted after resonant absorption. The sample was placed inside a proportional counter specifically designed for Mössbauer backscattering measurements. Helium‐10% methane flowgas was used to detect the conversion electrons. It is estimated from the observed spectra that this technique can be used to obtain Mössbauer backscattering spectra for iron‐containing surface layers 50–3000‐Å thick. Backscattering spectra for thicker surface layers (0.2–0.5 mil) were obtained by merely changing to an argon‐10% methane flow‐gas mixture and counting the 6.3‐keV internal conversion x rays rather than conversion electrons.