[en] The similarities and dissimilarities in the growth of diamond vs. cubic boron nitride (c-BN) were studied using quantum mechanical calculations. Great similarities were observed when considering the surface stabilization by H atoms. Very great similarities were recorded when considering the adsorption of various growth species to these materials. It was found necessary to avoid mixtures of B- and N-containing species in the gas phase during c-BN growth, since they should most probably result in a mixture of these species also on the surfaces. Greater dissimilarities were observed when studying the surface migrations on the diamond and c-BN surfaces and nucleation of the cubic phases on the corresponding hexagonal ones. Nucleation of diamond/c-BN on graphite/h-BN was found to be energetically feasible. This was calculated to be especially the situation for the armchair edge of the basal plane of h-BN and of the zigzag edge of the basal plane of graphite. These theoretical results can be used as guidelines in the strive towards thin film deposition of c-BN using gentle chemical vapour deposition methods like atomic layer deposition. (author)

[en] Micro-Raman and photoluminescence spectra of nitrogen-doped chemical vapour deposition (CVD) diamond films were studied. Spectra reveal the presence of diamond and graphitic carbon fractions in the sample and the presence of nitrogen-containing defects with luminescence lines peaking at 575 and 637 nm. Neutron irradiation of the sample sufficiently increases the broadband emission at 580 nm, subsequent annealing suppresses the broadband luminescence and increases the zero-phonon lines belonging to the nitrogen-vacancy defects.(author)

[en] We present the first scientific results, technical details, and recent developments in the Estonian Grid (EG). Ideas and concepts behind Grid technology are described. We mention some most crucial parts of the Grid system, as well as some unique possibilities in the Estonian situation. Scientific applications currently running on the EG are listed and the first scientific computations and results of the EG are discussed. The computations show that the middle ware is well chosen and the EG has remarkable stability and scalability. We present the collected results and experiences of the development of the EG and add some ideas of its near future. (authors)

[en] Possible theoretical frameworks for measurement of (arrival) time in nonrelativistic quantum mechanics are reviewed. It is argued that the ambiguity between indirect measurements by a suitable introduction time operator and direct measurements by a physical clock particle has a counterpart in the corresponding classical framework of measurement of the Newtonian time based on the Hamiltonian mechanics. (author)

[en] Current-voltage characteristics were measured for Au-TiO₂-Ag structures with TiO₂ layers of 30-180 nm thickness. In the case of negative bias on the Au electrode, the conduction currents through TiO₂ layers follow over several orders of magnitude the Fowler-Nordheim formula for the field emission, allowing attribution of the bulk currents to tunnelling, seemingly through a Schottky bather at the Au-TiO₂ junction. In the case of reversed polarity the currents are also observed, but cannot be interpreted as tunnelling. (author)

[en] In considering the packing density of working units of a device the frequency dimension (pixel ΔxΔyΔzΔω) should be also taken into account, in addition to the conventional space-only domain characterized by the pixel ΔxΔyΔz. Persistent spectral hole burning space-and-time domain holography is a spectacular of usefulness of the frequency dimension in very high density data storage and ultrafast processing (author)

[en] We investigated the formation of spin polarons (spin-polarized clusters) in weakly doped antiferromagnetically ordered CuO₂ planes of high-T_c cuprates. The influence of additional holes within a self-consistent mean-field approximation was calculated taking oxygen-oxygen hybridization (characterized by the parameter t) into account. The binding energy and polarization of the clusters were found to strongly depend on the value and sign of t, i.e. a positive t promotes the spin polaron formation, while a negative t suppresses it. For the common value t∼ 0.3-0.6 eV we obtained two polaron states with binding energies ∼ 0.5 eV and ∼ 0.3 eV. (author)

[en] New equations of motion of radiating elementary particles are derived by taking account of the induced angular momentum (eccentricity of the particles. The equations satisfy all ten conservation laws and generalize the Lorentz-Dirac equation. (author). 15 refs

[en] Short communication

[en] The previously determined structure of CsCuBr₃ is rationalized and can be understood as a combination of a Jahn-Teller effect and magnetic exchange interactions. Its hc structure is a consequence of a spin-Peierls effect. The unusual occurrence of this effect arises because of alternating stretched and bent Cu-Br-Cu superexchange paths. (author). 2 figs., 20 refs