No abstract available

[en] On 30 March 1995 the Institut for Landes- and Stadtentwicklungsforschung (Institute for Research on Regional and Urban Development) in North Rhine Westphalia held a workshop on the subject of 'Regional coordination of aeorogenerators'. The author deals with the energy-economic valuation of aerogenerators and reports on possibilities of connecting them to the network from the viewpoint of RWE Energie in the case of a windy highland service region. (orig.)

[en] Comparisons between unsupported and supported aluminum pressure cells for neutron-scattering experiments were performed. The supported cells are found to give an increase of approximately 33% in the ultimate pressure. (author)

[en] A bis(salicylaldiminato)nic le(II) catalyst was used for dimerization reactions of propene. The catalyst precursor was activated with a triethylaluminum/aluminum trichloride mixture in the presence of phosphines and 2, 4, 6-trichlorophenol. The influence of the various components on the catalytic activity and product distribution is shown.

[en] A series of 16 diiminophosphorane nickel (II) complexes was synthesized and used as catalyst precursors for dimerization reactions of propene. The nickel complexes were activated with methylalumoxane (MAO) and various phosphine additives. The influence of the ligand frameworks, the phosphine additives and the temperature was studied. Activities of 1 200 [kg oligomers/mol catalyst *h] and a selectivity of 76% for 2,3-dimethylbutene were achieved.

[en] A carbon-oxygen complex occurring in gallium arsenide crystals after annealing at around 700 °C is studied. Fourier transform infrared absorption measurements on the associated vibrational band at 2060 cm-1 under uniaxial stress reveal that the center has tetragonal symmetry. From the intensity of the ¹⁸O-related satellite band it is concluded that four oxygen atoms are involved. Ab initio local density calculations show that a tetragonal CO₄ molecule forms a stable entity in the gallium arsenide lattice

[en] For clarification of the unknown chemical composition of the electrically active N-O defects in silicon, an ingot with variable oxygen content and fixed nitrogen concentration was investigated by infrared spectroscopy. Shallow donor spectra taken at different sample positions, i.e., oxygen concentrations, show a strong oxygen influence on the absorption of the different N-O species, allowing determination of the number of oxygen atoms for each species via the corresponding mass-action law. From that, the energetically deepest defect N-O-5 is associated with a NO configuration, whereas the strongest complex N-O-3 has NO₂ composition. Further members of the shallow donor family contain three oxygen atoms

[en] The spectral fluctuation properties of various two- and three-dimensional superconducting billiard systems are investigated by employing the correlation-hole method. It rests on the sensitivity of the spectral Fourier transform to long-range correlations and is thus an alternative technique to study chaotic dynamics. First, we apply the method to the eigenfrequencies that are extracted from the measured resonances. Second, we analyze the unfolded raw spectra, including the shape of the resonances. The merit of the method lies in a clear separation of the statistics due to the positions and due to the shape of the resonances. However, we show that statistical fluctuations of the intensities of the resonances have a strong impact on the observable. Therefore, the visibility of the correlation hole is studied as a function of the number of independent statistical variables entering into the intensities. The visibility improves if independent spectra are superimposed. copyright 1997 The American Physical Society

[en] Fourier transform infrared absorption spectroscopy and secondary ion mass spectroscopy have been carried out on GaAs based dilute nitride layers after treatment with H⁺ or D⁺ ions. Formation of N-H (D-H) centers is detected by vibrational absorption bands of H (D). The modes are assigned to two different complexes, each involving one H (D) atom. A major fraction of the hydrogen in the layers might be not or only loosely bound to nitrogen.