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We investigate clean and atomic hydrogen exposed β-SiC(100) 3×2 surfaces by synchrotron radiation-based Si 2p core-level photoemission spectroscopy. The clean 3×2 surface reconstruction exhibits three surface and subsurface components. Upon hydrogen exposures, those surface and subsurface components are shifted to lower binding energies by large values, indicating significant charge transfer to the surface and subsurface regions, in excellent agreement with the recently discovered H-induced β-SiC(100) 3×2 surface metallization. In addition, the interaction of hydrogen results in a large reactive component at Si 2p supporting an asymmetric charge transfer in the third plane below the surface, in agreement with previous experimental investigations. However, the results are inconsistent with recent ab initio theoretical “frozen” calculations predicting H atom to be in a bridge-bond position. [ABSTRACT FROM AUTHOR]

The authors report an investigation on the adsorption of pentacene molecules on Cu(110) in the submonolayer and monolayer ranges using scanning tunneling microscopy and low-energy electron diffraction. They identify and characterize three different phases for increasing pentacene coverage. For very low coverages [<=0.1 ML (monolayer)] pentacene molecules are highly mobile and adsorbed uniaxially oriented along the [110] substrate direction. For higher coverages the ordering along the [001] direction improves, until a p(7×2) structure with imperfect registry along the [110] direction is formed at 0.89 ML. In both phases pentacene molecules occupy the Cu(110) troughs along the [110] direction. For even higher coverage (1.0 ML), a slight rotation of the molecular adsorption site gives rise to a complex (6 1/-1 4) structure based in a c(12×2) cell. The appearance of two domains generates a long-range wavelike ordering. Annealing of the adlayer results in the formation of supramolecular complexes. [ABSTRACT FROM AUTHOR]

In this article, the interplay between electronic and geometric properties in transition metal silicide systems is presented using as a model system Fe-Si binary compounds. When iron silicides are epitaxially grown on Si(111), several different phases can be obtained, depending on the preparation conditions. In particular, for a 1:1 Fe:Si stoichiometry, there are two different phases possible: FeSi(CsCl) and ∊-FeSi. The former is a metastable phase, stabilized through epitaxy, while the latter is the bulk-stable phase for a 1:1 composition. Although the two have nominally the same composition, their different structures give rise to distinct electronic properties in each material. Their electronic structures have been probed by angle-resolved photoemission. In this article the results of this analysis will be presented along with the main properties of both compounds. [ABSTRACT FROM AUTHOR]

Photoelectron spectroscopy data suggest that the mechanism of enhanced oxidation of Si promoted by multilayers of K deposited on its surface is based on the formation of potassium oxides, identified as K2O2 and KO2, that transfer oxygen efficiently to the Si substrate upon annealing at 900 K. [ABSTRACT FROM AUTHOR]

A recipe to produce ultrathin gate oxides by K-promoted catalytic oxidation of Si is described. The thickness of the final oxide depends linearly on the amount of K predeposited. The resulting oxide is chemically homogeneous. The process takes place at temperatures much lower than those used in thermal oxidation. The maximum temperature required to desorb the catalyst is 600 °C. [ABSTRACT FROM AUTHOR]

We take advantage of complementary high-resolution experimental techniques and theoretical tools to get insight into the α-Sn/Ge(111) triangular lattice surface consisting of sp electrons. We report a (3×3) phase, characterized by a charge ordering settled by electronic correlation, which appears between the known metallic-(3×3) and Mott insulator phases. We identify the atomistic mechanism behind the stabilization of this phase and interpret these findings on the basis of theoretical calculations. We disentangle the role of the various degrees of freedom in the stability of the different phases found and describe the stepwise surface changes between the metallic and Mott insulating phases. [ABSTRACT FROM AUTHOR]

The clean surface of Au(100) presents a complex reconstruction characterized by a hexagonal topmost layer. We report an angle-resolved photoemission study of the electronic structure of this surface, including an analysis of the Fermi surface, combined with structural information from low-energy electron diffraction and scanning tunneling microscopy. In the complex Fermi surface map found, we identify different contributions from the bulk bands, from interface states located below the hexagonal topmost layer, and from the hexagonal topmost layer itself. The electronic states related to this layer exhibit quasi-one-dimensional character, in agreement with the chain aspect of the reconstructed layer, as demonstrated by their dispersion, periodicity, and reciprocal space location. [ABSTRACT FROM AUTHOR]