Spatially resolved valence band study of nanostructured carbon films containing transition metal nanocrystals

We studied the electronic structure of nanostructured C films produced by ultrasonic cluster beam deposition with the intention to find out the bonding configuration of the C network and to determine the modification induced by transition metal cluster inclusion in the film. Exploiting the energy and spatial resolution of the Spectromicroscopy beamline at Elettra Synchrotron, we were able to follow the valence band features depicted in 95.0 eV-excited photoemission spectra with a 0.5 μm lateral resolution. The spectroscopic results allowed to conclude that nanostructured C films have a mixed sp 2/sp3 bond configuration and an amorphous-like structure and that those features are uniformly distributed in the film. The inclusion of metal cluster (Ni, Ti and Mo) in the film strongly modifies the valence band spectra. The surface stoichiometry of the embedded metal clusters and the keeping of their metallic nature are determined by a detailed analysis of the spatial dependence of the ultraviolet photoemission spectroscopy (UPS) spectra and by a comparison with previous studies on metal-carbide and -oxide surfaces.