The oxidation of chalcopyrite and pyrite was examined using Fe-K- and Cu-K-edge REFLEXAFS spectroscopy. The Fe XANES of the pyrite proved to be a very sensitive indicator of oxidation, revealing the development of a goethite-like surface species; the EXAFS data showed an increasing O:S ratio with the degree of oxidation and gave Fe–O distances of c. 1.9 Å. On the oxidized chalcopyrite surfaces, the development of Fe-O and Cu-O species was observed, with both the XANES and EXAFS revealing the progressive development of these species with oxidation. Differences in the sensitivity of the XANES and EXAFS to the degree of oxidation can be related to the degree of long range order and changes in the intensity of the pre-edge feature of the Fe are a function of its oxidation state and coordination geometry in the surface species.

Formation of a nanometer-scale oxide surface layer is common when a material is exposed to oxygen-containing environment. Employing aberration-corrected analytical transmission electron microscopy and using single crystal SnSe as an example, we show that for an alloy, a second thin amorphous layer can appear underneath the outmost oxide layer. This inner amorphous layer is not oxide based, but instead originates from solid-state amorphization of the base alloy when its free energy rises to above that of the metastable amorphous state; which is a result of the composition shift due to the preferential depletion of the oxidizing species, in our case, the outgoing Sn reacting with the oxygen atmosphere.

Effects related with the attenuation and deflection suffered by an electron beam when it passes through a carbon conductive coating and an oxide film layer on the surface of bulk samples are studied by Monte Carlo simulations and energy dispersive spectroscopy with electron excitation. Analytical expressions are provided for the primary beam energy and intensity losses and for the deflection of the incident electrons in both layers, in terms of the incidence energy, the film mass thicknesses, and the atomic number of the oxidized element. From these analytical expressions, suitable corrections are proposed for the models used to describe the X-ray spectrum of the substrate, including also the contribution of the X-rays generated in the oxide and conductive films and the characteristic X-ray absorption occurring in those layers. The corrections are implemented in a software program for spectral analysis based on a routine of parameter refinement, and their influence is studied separately in experimental spectra of single-element standards measured at different excitation energies. Estimates for the layer thicknesses are also obtained from the spectral fitting procedure.