Fine determination of interatomic distances on surface using extended energy-loss fine structure (EELFS) data: Peculiarities of the technique

Abstract

For determination of interatomic distances on a surface we use spectra below the lines of backscattered electrons and below the Auger lines. In contrast to other authors, who record spectra in dN/dE mode for extended energy-loss fine structure (EELFS) analysis, the integral N(E) mode is used with further filtering of the structure-dependent oscillations by original software. The sequence of structure-dependent oscillation extraction from the energy-loss spectrum is presented, including the following main stages: synthesis of peak and inelastic background and detection of inelastic oscillations; normalization of the inelastic spectrum; recalculation of the spectrum to K-space; and Fourier transformation. Good agreement between theoretical and experimentally obtained interatomic distances for various systems (multicomponent grain boundary segregations in steels, hard diamond-like coatings and films generated on the surface of cutting tools with engineered coatings) is observed. Detailed results of application of EELFS for investigation of the atomic structure of these systems are presented. In particular, the results of EELFS analysis of hard amorphous hydrogenated carbon films show the ability of this method to resolve interatomic bonds of different types (sp, sp2, sp3, aromatic bonds). The 'carbon-hydrogen' distances are also determined.