Graphene grown epitaxially on SiC has been proposed as a material for carbonbased electronics. Understanding the interface between graphene and the SiC substrate will be important for future applications. We report the ability to image the interface structure beneath single-layer graphene using scanning tunneling microscopy. Such imaging is possible because the graphene appears transparent at energies of 1 eV above or below the Fermi energy (E ± F ). Our analysis of calculations based on density functional theory shows how this transparency arises from the electronic structure of a graphene layer on a SiC substrate.

With or without the metal: Recently, the Grotthuss mechanism of proton transfer in water has been described in detail. A similar mechanism has been found in the vicinity of transition‐metal ions, which leads to the formation of Zundel and Eigen complexes (see picture).

The basal (0001) surface plane of R-Al 2 O 3 has been extensively studied both by experimental techniques and applications of theory. Although this surface is not easily created upon cleavage, it grows in during aluminum oxidation and has been shown to be one of the lowest energy surfaces of alumina. Upon heating under vacuum, this (0001) surface of R-Al 2 O 3 undergoes a series of reconstructions. The final structure obtained at ∼1700 K is an air-stable termination known as the ( 31 × 31)R ( 9°reconstruction. Alternatively, this reconstructed surface can also be obtained at lower temperatures by aluminum deposition on a clean Al 2 O 3 (1 × 1) basal plane surface. Applying density functional theory within the generalized gradient approximation to a model surface, we show that the transformation from the (1 × 1) termination to ( 31 × 31)R ( 9°is accompanied by a dramatic change in the band gap associated with the ceramic's surface. Specifically, the (1 × 1) termination is insulating for both surface and deeper "bulk-like" atoms, while the ( 31 × 31)R ( 9°termination results in a metallic surface aluminum coating that behaves very much like an aluminum (111) surface. Although some experimental evidence for the ( 31 × 31)R ( 9°metallic surface states exists, it has generally been ignored, and both the (1 × 1) and ( 31 × 31)R ( 9°terminations are commonly treated as insulating. The metallic surface character of the reconstructed basal plane of R-Al 2 O 3 may present interesting implications for future applications of heat-treated alumina surfaces. † Part of the special issue "John T. Yates, Jr., Festschrift".

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Aluminum is an important engineering material used in a variety of applications. Under ambient conditions, a self‐limiting oxide layer forms on the aluminum surface and protects the underlying metal from further oxidation; this oxidation of aluminum affects its mechanical strength. Accordingly, we consider a simple, atomic‐level model of the effect of oxidation on crack formation by examining how cracks form in aluminum and its fully oxidized stable partner α‐Al2O3; the valence electron density plot of the latter is shown in the picture, in which a 1 Å crack has been introduced. We find that the sharp falloff in electron density at Al2O3 surfaces provides a nanoscale explanation for the brittleness of alumina. Structural relaxation diminishes the acceptability of simple interaction models in macroscale simulations and suggests such relaxation should be accounted for in the future.