Electron energy-loss near-edge structure of internal interfaces by spatial difference spectroscopy

Internal interfaces determine the macroscopic mechanical and electronic properties of materials. Their investigation is therefore essential for an understanding of the relationship between microstructure and the materials properties. Besides the atomic structure, the bonding and electronic structure on an atomic scale are of interest. This information is contained in the interface-sensitive component of the electron energy-loss near-edge structure (ELNES). It can be extracted by the spatial difference method. Such spectra have already been interpreted with respect to the bonding and the local atomic environment of the atoms at the interface. Here we assess critically the application of the spatial difference for the investigation of internal interfaces. The method is subjective because a suitable scaling factor has to be chosen. As a guideline we propose to minimize the number of turning points in the difference spectrum. With this hypothesis we successfully determine the ELNES arising from atoms at two internal interfaces between a metal and a ceramic. This reveals qualitatively which type of bonding is present at the interface and quantitatively how many atoms are involved in it.