Investigation of Ti/CuO interface by X-ray photoelectron spectroscopy and atomic force microscopy

The Ti/CuO interface has been studied by the techniques of X-ray photoelectron spectroscopy and atomic force microscopy. Thin films of titanium were deposited on a CuO substrate at room temperature by the e-beam technique. The photoelectron spectra of titanium and copper were found to exhibit significant chemical interaction at the interface. The titanium overlayer was observed to get oxidized to TiO₂, while the CuO was observed to get reduced to elemental copper. This chemical interaction was observed to occur until a thickness of 7 nm of the titanium overlayer. For thicknesses greater than this value, the presence of unreacted titanium in the sample was detected. Barrier characteristics at the Ti/CuO interface were also carried out for substrate temperatures of 300°C, 400°C, 500°C, and 600°C as a function of the titanium overlayer thickness. A linear trend in the barrier thickness of the overlayer was observed between 400°C and 600°C substrate temperatures. The atomic force microscopy micrographs of the unannealed samples depicted layer-by-layer growth of elemental titanium on copper. At the Ti/CuO interface in such samples, the micrographs exhibited island formation of TiO₂ corresponding to the Volmer-Weber growth model. This formation has been interpreted as the relaxation in the strain energy. The percentage coverage of the underlying substrate by the TiO₂ islands showed a linear trend for the thicknesses of the titanium overlayer investigated. The average size of these islands also showed a linear trend as a function of the thickness of the overlayer.     

Zink

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Bestimmung des Schwefels in organischen Verbindungen

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Improving the energies of approximate wave functions using the concepts of density functional theory

A simple method, derived from DFT, for improving the energy of a trial density is modified for the case of atoms. It is assumed that errors in the interelectronic repulsion are the only significant ones. The errors in the energies of single‐ζ Slater orbitals for the atoms from He to Ne are reduced an average factor of 21. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001     

Kupfer

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Exploiting planarity in separation routines for the symmetric traveling salesman problem

At present, the most successful approach for solving large-scale instances of the Symmetric Traveling Salesman Problem to optimality is branch-and-cut. The success of branch-and-cut is due in large part to the availability of effective separation procedures; that is, routines for identifying violated linear constraints.

For two particular classes of constraints, known as comb and domino-parity constraints, it has been shown that separation becomes easier when the underlying graph is planar. We continue this line of research by showing how to exploit planarity in the separation of three other classes of constraints: subtour elimination, 2-matching and simple domino-parity constraints.     

MTV-G experiment: Probing non-standard strong gravitational field at nuclear scale using geodetic precession

A new experiment named MTV-G, probing a large electron spin-precession due to a possible strong gravitational field, which predicted by large extra dimension model, is started at TRIUMF from 2011. In an electron-nuclear scattering experiment, a strong gravitational field is tested as a large spin precession effect caused by geodetic precession predicted by general relativity theory as a result of a warped space-time around nuclei. Experimental design using spin polarized electron source and Mott-spin analyzer, commissioning experiment and the preliminary results are described.