Depth-selectiveFe57conversion-electron Mössbauer spectroscopy. II. Experimental test—angular effects, accuracy

An experimental investigation of the depth and surface selectivity in depth-selective ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ conversion-electron Mössbauer spectroscopy (DCEMS) has been performed by using a high-resolution electron-energy analyzer combined with a Mössbauer spectrometer. DCEMS spectra have been recorded in ultrahigh vacuum at different electron energies E from 6.5 to 7.3 keV (with 2.7% energy resolution) and, for the first time, at different electron-emission angles θ relative to the absorber surface normal (from θ=10° to 72°), using a test absorber consisting of a thin α-Fe layer on a thick stainless-steel substrate. The α-Fe and stainless-steel Mössbauer spectral areas were found to be in very good agreement with theoretically calculated values. The predicted angular effects are verified; in particular, it is confirmed that the surface signal is enhanced by measuring at glancing angles relative to the absorber surface.