X-ray spectroscopy of carbon-encapsulated iron nanoparticles

Abstract

The composition and electronic structure of carbon-encapsulated iron nanoparticles Fe@C are examined by X-ray photoelectron, X-ray absorption, and resonant emission spectroscopy methods. It is found that the core in the Fe@C nanocomposite is in the metallic state with an impurity of iron carbide, which is preserved for two years. Experimentally measured spectra are compared to the calculations of the electronic structure of graphene performed at the density functional theory level. It is revealed that the Fe@C carbon shell can be presented as several graphene layers with Stone-Wales topological defects. Based on the measurements of X-ray resonant emission K alpha spectra of carbon, the energy band dispersion of the carbon shell of Fe@C nanoparticles is investigated and the manifestation of Stone-Wales defects in them is shown.