[en] By the present thesis it was shown that the internal photoemission on thin metal-semiconductor heterostructures can by quantitatively described starting from known material quantities, if the scattering processes of hot charge carriers in the metal film are regarded. from this an aimed efficiency improvement of infrared detectors, which are based on internal photoemission, results as well as a more precise determination of Schottky barrier heights

No abstract available

[en] Diffuse reflectance infrared Fourier transform measurements were performed on tin oxide based thick film gas sensors operated in normal working conditions. We characterised SnO₂ sensors at different temperatures between room temperature and 300 deg. C. The results show the presence of different surface OH groups as well as coordinated water on the SnO₂ sensor surface. Their intensity changes with temperature. During the temperature cycles the bands' peak positions are reversibly changed but their intensity is not. CO measurements were performed at 300 deg. C at different humidity levels (0 and 50% r.h.) on un-doped and Pd-doped sensors. In the presence of CO we observed in the spectra: a decrease of the OH groups on the SnO₂ surfaces, the appearance of gaseous CO₂ and CO in the pores of the sensitive layer and an increase of hydrated protons and of the free charge concentration. The effects are dramatically influenced by the water vapour concentration, temperature, dopands (Pd) and can be correlated with simultaneously performed sensor resistance measurements

[en] In view of the impending tasks for securing Germany as an industrial site, the imminent stiffening of competition within the European power economy, and, not least, worldwide environmental problems it is clear that the future of the German power economy as a whole hinges on the restoration of stable and thus adequately calculable political framework conditions. This goal can only be achieved on the basis of an all-inclusive energy-political consensus. The author believes the following two points to be essential to such a consensus. He considers the civil utilisation of nuclear energy an economic and ecological necessity for the time being and urges that the operation of existing power plants be secured against political interference and that radwaste disposal facilities be provided. Secondly, he demands that the financing of German hard coal must in future be non-discriminatory and dissociated from any special levies on electricity. RWE is prepared to use the potential of renewable energies as economically reasonable and to exploit economic rationalisation potentials including the development of cogeneration. RWE agrees to include this commitment in an overall energy-political consensus. (orig.)

[en] Ion irradiation during deposition strongly influences the stress state of this films. Tensile stress can be turned into compressive stress. With an appropriate ion-to-atom arrival ratio films with zero stress can be deposited. Cr and B films which usually show high tensile stress values were formed by evaporation under bombardment with Ar ions in the energy range of 3 to 15 keV. The dependency of the resulting stress states on process parameters such as ion energy, ion-to-atom-ratio and residual gas pressure is discussed and compared with findings of other authors. First results on the influence of ion beam modified stress state on the tribo-adhesive behaviour of coatings using the scratch test are presented. (orig.)

No abstract available

[en] An existing theory on the angular distribution of Penning electrons is extended to the emission of electrons which have other than σ symmetry with respect to the internuclear axis. The formulae is applied to experimental data for He(2¹S, 2³S)-Ar. The main result of the evaluation is that the Penning process leads exclusively to He-Ar⁺ states the spatial wavefunctions of which have Σ symmetry. On the basis of this statement it is shown that the relative population of the two Ar⁺(²Psub(3/2), ²Psub(1/2)) fine-structure levels depends on the collision energy. The ratio σ(²Psub(3/2))/ σ(²Psub(1/2)) is calculated as a function of collision energy and excellent agreement is found with available experimental data. (author)

[en] Most of the visible xenon laser lines by a study of the time dependence of spontaneous emission whose delay is unambiguously correlated with the ionic state have been assigned. For 11 lines, ambiguities are resolved, or first assignments are given

[en] Low-energy electron emission induced by 1-4 keV Ne⁴⁺ ion impact on an Al surface was analyzed. Distinct lines observed near 22 eV are attributed to Auger electrons ejected from doubly excited Ne^2* decaying well above the surface. Spectral structures near 11 eV are primarily associated with the decay of bulk plasmons. After instrumental effort of extending the capability of the spectrometer to measure electrons with energies as low as 2 eV, we made observations of intense spectral structures near 6.5 eV, which are likely to be due to the decay of surface plasmons. Absolute electron yields were studied as a function of the incidence angle of the Ne⁴⁺ projectile and were interpreted by means of model calculations

No abstract available