The surface science of titanium dioxide

Zinc oxide is a unique material that exhibits semiconducting and piezoelectric dual properties. Using a solid–vapour phase thermal sublimation technique, nanocombs, nanorings, nanohelixes/nanosprings, nanobelts, nanowires and nanocages of ZnO have been synthesized under specific growth conditions. These unique nanostructures unambiguously demonstrate that ZnO probably has the richest family of nanostructures among all materials, both in structures and in properties. The nanostructures could have novel applications in optoelectronics, sensors, transducers and biomedical sciences. This article reviews the various nanostructures of ZnO grown by the solid–vapour phase technique and their corresponding growth mechanisms. The application of ZnO nanobelts as nanosensors, nanocantilevers, field effect transistors and nanoresonators is demonstrated.

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Zinc oxide nanostructures: growth, properties and applications

The Interaction of Water with Solid Surfaces: Fundamental Aspects Revisited

Surface Science Studies of the Photoactivation of TiO2New Photochemical Processes

S. Pillai would like to acknowledge the UNSW Faculty
of Engineering Research Scholarship. K.R. Catchpole
acknowledges the support of an Australian Research Council fellowship.

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Surface plasmon enhanced silicon solar cells

Determining the bulk-absorption component in ion-desorption surface EXAFS spectra

The recently discovered antiferromagnetic 1/1 Au-Al-Tb approximant exhibits a whirling spin order oriented along the [111] direction. Here we report an investigation of the atomic structure of the (111) surface by scanning tunneling microscopy and density functional theory (DFT) calculations. Scanning tunneling microscopy reveals a Tb-terminated step-terrace morphology, with step heights appearing to minimize the number of broken bulk icosahedra. The atomic structure of the terraces is bias dependent, with Tb atoms imaged under positive bias and Au/Al atoms under negative bias. The surface is found to reconstruct, with the Au/Al atoms producing a linear row structure, an example of a surface reconstruction in a Tsai-type system. These observations are confirmed by DFT calculations.

Atomic structure of the (111) surface of the antiferromagnetic 1/1 Au-Al-Tb approximant

L'etude par XANES pour un degre de recouvrement d'une demi monocouche montre une forte dependance azimutale qui n'a pas ete montree pour des adsorbats atomiques. La resonance pres du seuil n'est pas simplement dominee par le soufre-nickel pres de la diffusion du voisinage

Azimuthally-dependent x-ray absorption near edge structure for sulphur adsorbed on nickel (110)

Alkali metal coadsorption systems represent a step along the pathway from simple model adsorbate overlayers to more technologically relevant real systems. However, such is their complexity that very few systems have been structurally determined. Here we present a surface X-ray diffraction investigation of one of these systems, Ni(100)-(3×3)-(Cs+O). Here a structural determination is particularly challenging due to the presence of three species in the surface layers and by the size of the unit cell. As a first step, anomalous scattering has been used to determine whether there is a contribution of the nickel substrate to the fractional order diffraction intensity. Measurements of the fractional order rods at 10 eV and 200 V below the nickel K edge (8333 eV) were used to probe the nickel contribution to the fractional order rods. It was found that the intensity of the scattering was unchanged, indicating that the fractional order peaks are caused by scattering from the coadsorbates only. This shows that the nickel surface layers are not changed by the adsorption and thus sets a useful constraint on the number of possible structures.

A SURFACE ANOMALOUS DIFFRACTION STUDY OF THE Ni(100)(3×3)-(Cs+O) SYSTEM

We present a study of the adsorption of pentacene (Pn) molecules on the high symmetry (fivefold, threefold, and twofold) surfaces of the icosahedral (i) Ag–In–Yb quasicrystal. We also compare the results with adsorption of Pn on a surface of a periodic crystal related to this quasicrystal, the (111) surface of the Au–Al–Tb 1/1 approximant. Scanning tunneling microscopy reveals that Pn molecules on the quasicrystal surfaces are aligned along the high symmetry directions of the substrates and selectively adsorb on Yb atoms and thus exhibit quasicrystalline order. Pn molecules on the Au–Al–Tb approximant surface also preferably adopt Tb sites. The behavior of selective adsorption can be understood in terms of the geometry and electronic properties of the adsorbate and substrate. The Yb–Yb (Tb–Tb) separations are comparable to the C–C or H–H distances in a Pn molecule. Pn is an electron donor, whereas the unoccupied electronic states of the substrate are dominated by the rare earth atoms, suggesting that there is an electronic transfer between the Pn molecules and Yb (Tb) atoms. 

Ronan McGrath

Papers

Determining the bulk-absorption component in ion-desorption surface EXAFS spectra

Atomic structure of the (111) surface of the antiferromagnetic 1/1 Au-Al-Tb approximant

Azimuthally-dependent x-ray absorption near edge structure for sulphur adsorbed on nickel (110)

A SURFACE ANOMALOUS DIFFRACTION STUDY OF THE Ni(100)(3×3)-(Cs+O) SYSTEM

Growth of pentacene molecules on Tsai-type quasicrystals and related crystal surfaces