STRUCTURE OF THE COPPER-MONOLAYER PLATINUM-ELECTRODE INTERFACE AS MEASURED IN IN-SITU X-RAY-ABSORPTION SPECTROSCOPY

Using a large polycrystalline Pt film electrode with one layer of electrochemically adsorbed Cu, we have measured the EXAFS of Cu at the K edge through a grazing-incidence fluorescence-detection experiment while the sample was under electrochemical control. The quality of the data permit reliable analysis of the k(chi) spectrum up to 800 eV above the K edge. Measurements with x-ray electric field vector parallel and perpendicular to the surface were made on the same monolayer. The results indicate that the neighbors of Cu are: O at 2.06 angstrom, Pt at 2.58 angstrom, and Cu at 2.62 angstrom. These are similar to what is expected from considerations of metallic or covalent radii.