Surface States

We present ab initio pseudo-potential plane-wave total-energy calculations for the geometric and electronic structure of the CO-covered Pd(110) surface. Our calculations were performed within the local-density approximation (LDA) of density functional theory (DFT). There has been some controversy as to whether CO prefers to adsorb at a bridge or on-top site when exposed to Pd(110). Total energy calculations for a CO monolayer adsorbed at the on-top and bridge adsorption sites revealed the bridge site adsorption to be favored by 0.59 eV per CO molecule. The preferential adsorption of CO to the bridge site was further corroborated by our band-structure calculations, with only the bridge site results being in good agreement with recent inverse photoemission experiments.

The low temperature RF plasma treatment was used to control the surface chemistry and optical property of TiO 2 thin films deposited by RF magnetron sputtering with a very good uniformity at 300 °C substrate heating temperature. The XRD pattern indicates the crystalline structure of the film could be associated to amorphous structure of TiO 2 in thin film. The plasma treatment of TiO 2 film can increase the proportion of Ti 3+ in Ti2 p and decrease in carbon atoms as alcohol/ether group in C1 s at the surface. The optical transmittance of the film was enhanced by 50% after the plasma treatment. The surface structure and morphology remain the same for untreated and low-pressure plasma-treated films. Therefore, increase in the optical transmission could be due to change in surface chemistry and surface cleaning by plasma treatment.

The normal field instability in magnetic liquids is investigated experimentally by means of a radioscopic technique which allows a precise measurement of the surface topography. The dependence of the topography on the magnetic field is compared to results obtained by numerical simulations via the finite-element method. Quantitative agreement has been found for the critical field of the instability, the scaling of the pattern amplitude and the detailed shape of the magnetic spikes. The fundamental Fourier mode approximates the shape to within 10% accuracy for a range of up to 40% of the bifurcation parameter of this subcritical bifurcation. The measured control parameter dependence of the wavenumber differs qualitatively from analytical predictions obtained by minimization of the free energy.

Thin AgCl layers photocatalytically oxidize water to O 2 under appropriate conditions. The photoactivity of AgCl extends from the UV into the visible light region in a process known as self-sensitization, which is due to the formation of silver during the photoreaction. This silver can be almost quantitatively reoxidized electrochemically, making it feasible that a thin AgCl layer deposited on a conducting substrate can be used as a photoanode for water splitting if coupled with an appropriate photocathode. The silver chloride/silver cluster phase boundary plays a decisive role in the photocatalytic silver chloride electrode system. We have therefore studied this interphase by means of quantum chemical calculations from which we report first results, specifically for the (Ag) 115 (AgCl) 192 composite. Clusters of semiconducting materials are interesting considering their application as a photocathode in such a device. In this context, we also report the synthesis and properties of l...