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The local atomic structure and chemical nature of newly synthesized silver nanoparticles (AgNPs) functionalized with the organic thiol allylmercaptane (AM) have been probed combining synchrotron radiation-based techniques: Xray photoelectron spectroscopy (XPS) and X-ray absorption fine structure spectroscopy (XAFS). Complementary information about the chemical and electronic structure is obtained combining XAES and XPS data. These results coherently suggest a core shell morphology of the NPs resulting in metallic Ag cores surrounded by Ag2S-like phase. The external layer of AM molecules is grafted to the NPs surface through Ag-S chemical bonds. NP size and composition were found as a function of the chemical synthetic route (i.e., Ag/A.M molar ratio). It was observed that by increasing the Ag/AM ratio, larger AgNPs were obtained. It was found that a higher Ag/AM molar ratio leads to an increasing of the Ag2S layer thickness, while the external AM layer remains unvaried. TEM analysis showed well-separated and dispersed nanoparticles, and ED pattern allowed one to identify two different phases of single crystal corresponding to the presence of Ag face-center-cubic single-crystal symmetry, together with weak diffraction spots in agreement with Ag2S cubic symmetry in Im3m space groups

The adsorption on the TiO(2) surface of two dipeptides AE (L-alanine-L-glutamic acid) and AK (L-alanine-L-lysine), that are "building blocks" of the more complex oligopeptide EAK16, has been investigated both theoretically and experimentally. Classical molecular dynamics simulations have been used to study the adsorption of H-Ala-Glu-NH(2) and H-Ala-Lys-NH(2) dipeptides onto a rutile TiO(2) (110) surface in water solution. Several peptide conformers have been considered simultaneously upon the surface. The most probable contact points between the molecules and the surface have been identified. Carbonyl oxygens as well as nitrogen atoms are possible Ti coordination points. Local effects are responsible for adsorption and desorption events. Self-interaction effects can induce molecular reorientations giving less strongly adsorbed species. The chemical structure and composition of thin films of the two dipeptides AE and AK on TiO(2) were investigated by XPS (X-ray photoelectron spectroscopy) measurements at both O and N K-edges. Theoretical ab initio calculations (DeltaSCF) were also performed to simulate the spectra, allowing for a direct comparison between experiment and theory.