Surface structure, binding energy

The structure formed when one end of a chain is tethered to d = 2 surface, is referred to as a grafted layer or more commonly as a brush . Brushes can be made by attaching a functional group to one end of a chain that can then bind to the surface. The binding energy can either be quite high (several hundred kaJ), in which case the end is chemically attached,or of order ten kaT, in which case it is physi-adsorbed. Diblock copolymers, in which one of the blocks (usually the shorter one) adsorbs strongly to the surface, while the other does not, also form brushes, as well as a... 

Room temperature deposition of silver on Pd(lOO) produces a rather sharp Ag/Pd interface [62]. The interaction with a palladium surface induces a shift of Ag 3d core levels to lower binding energies (up to 0.7 eV) while the Pd 3d level BE, is virtually unchanged. In the same time silver deposition alters the palladium valence band already at small silver coverage. Annealing of the Ag/Pd system at 520 K induces inter-diffusion of Ag and Pd atoms at all silver coverage. In the case when silver multilayer was deposited on the palladium surface, the layered silver transforms into a clustered structure slightly enriched with Pd atoms. A hybridization of the localized Pd 4d level and the silver sp-band produces virtual bound state at 2eV below the Fermi level. 

These results show that the electrochemical measurements can, via ab initio simulations, be linked to phenomena at the atomic level, such as structural and electronic effects and, in this case, binding energies on the surfaces. 

Here, we demonstrate clear and direct evidence for the modified electronic structures of surface Pt atoms in Pt-Co and Pt-Ru by using EC-XPS [Wakisaka et al., 2006]. The sample electrode was transferred between an XPS chamber and an electrochemical (EC) chamber without exposure to air (to minimize contamination of the surface). All photoelectron spectra, including the valence level region) were taken by using a monochromatic Al Ka (hv = 1486.58 eV). The uncertainty of binding energy measurement was less than + 0.03 eV. 

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