Structure of cobalt nanoparticles as studied by X-ray absorption spectroscopy

Ab initio modeling is used to analyze the specific near-edge features of the X-ray absorption K spectra of ∼3-nm cobalt nanoparticles. It is established that the observed differences between the spectra of the nanoparticles and those of bulk cobalt samples are due to contribution from atoms of the nanoparticles’ surface layer, the local environment of which is considerably different from that of atoms in the bulk of the nanoparticle. It is also established that the local environment of cobalt atoms in the nanoparticle bulk corresponds to the FCC structure of bulk metal, and the fraction of such atoms is found to be 65 ± 5%.