Chemical characterization of protein based binders in painting samples by means of ToF-SIMS: Tests on ancient and model samples

In the present work we investigated the possibility of identifying proteinaceous binders, typically used in "tempera" painting, by means of ToF-SIMS and PCA method. ToF-SIMS measurements were performed on cross-sections taken from a painted wooden crucifix of the 15th century. The results of the ToF-SIMS analysis are compared with those obtained by GC-MS. ToF-SIMS measurements were carried out also on model samples simulating the layered structure of real painting cross sections to elucidate how matrix effects can influence the identification of protein based binding media. A discrimination between rabbit glue and casein on the basis of the comparison of the ToF-SIMS results for the ancient samples with those obtained from reference compounds appears to be difficult. This is mainly due to matrix effects that are relevant for these complex, multicomponent samples, as indicated by the PCA results for model painting samples of known composition. On the other hand, PCA method and the observation of characteristic fragment ions in the spectra should allow to determine the presence of egg in painting layers. © 2014 Elsevier B.V

Structure of a single atomic layer of nickel deposited on the Pt(111) surface determined by low energy electron diffraction

The structure of ultrathin films of Ni deposited at room temperature on the Pt(111) surface has been determined by low energy electron diffraction (LEED) intensity analysis. The first monolayer of Ni grows pseudomorphically on Pt(111) despite the 11% mismatch between the lattice parameters of nickel and platinum. The results of the analysis also show that the Ni atoms occupy face-centered-cubic sites on the substrate surface. These results in part confirm previous data obtained by X-ray photoelectron diffraction, but also provide more reliable data on the site assignment