We report a detailed morphological and structural characterization of iron/iron oxide core-shell nanoparticles with x-ray diffraction and x-ray absorption spectroscopy performed at both the Fe and O $K$ edges. Core-shell nanoparticles with core size ranging from 7 to 21 nm were synthesized using the inert gas condensation technique followed by 12 h of controlled surface oxidation. Rietveld analysis of diffraction patterns shows the presence of α-Fe nanoparticles surrounded by a 2–3 nm-thick oxide layer with a disordered cubic spinel structure. Magnetite $\left({\mathrm{Fe}}_3{\mathrm{O}}_4\right)$ and maghemite $(\gamma -{\mathrm{Fe}}_2{\mathrm{O}}_3),$ two different iron oxides, share this lattice structure, but x-ray diffraction was not able to distinguish between the two. An analysis of the Fe and O x-ray absorption spectra in both the near-edge and the extended energy regions is described. The analysis of the extended spectra was performed using the ab initio calculation of all significant contributions to the absorption cross section. We show that there are size-dependent changes in the local structure and oxidation state of the oxide shell, the relative fraction of maghemite increasing at the expense of magnetite as the core dimensions decrease. This size/structure correlation has been explained in terms of morphological and structural disorder arguments

The BEAR (Bending Magnet for Emission Absorption and Reflectivity) beamline is installed at the right exit of the 8.1 bending magnet at ELETTRA. The beamline — in operation since January 2003 — delivers linear and circularly polarized radiation in the 5 – 1600 eV energy range. The experimental station is composed of a UHV chamber for reflectivity, absorption, fluorescence and angle resolved photoemission measurements and a UHV chamber for in‐situ sample preparation.

Surface-extended x-ray-absorption fine-structure studies on the Ni(111)-c(4×2)-CO system show that CO adsorbs in threefold-coordinated hollow sites. This result is in conflict with the adsorption-site determination via molecular vibrational frequencies, which for this system led to an assignment of a bridge site.

The spin and orbital configuration of magnetic metal phthalocyanines (MPcs) deposited on metallic substrates are strongly influenced by the rehybridization of the molecular states with the underlying metal. FePc, CoPc, and CuPc isolated molecules are archetypal systems to investigate the interrelationship between magnetic moments and orbital symmetry after deposition on a metallic substrate. MPcs form long-range ordered chains self-assembled along the reconstructed channels of the Au(110) surface. X-ray magnetic circular dichroism from the ${L}_{2,3}$ absorption edges of Fe, Co, and Cu shows that the orbital and spin configuration are strongly modified upon adsorption on the Au(110) surface if the orbitals responsible of the magnetic moment are involved in the interaction process. The magnetic moment for a single layer of molecular chains is completely quenched for the CoPc molecules, fully preserved for the CuPc and reduced for the FePc ones. The modified magnetic configuration is confined to the very interface layer, i.e., to the MPc molecules bound to the metal substrate up to the compact packing of the single layer. The different response can be rationalized in terms of the symmetry/orientation of the metal-ion $d$ states interacting with the substrate states, as indicated by density functional theory calculations in agreement with experimental findings.