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Es werden die Untersuchungen und Überlegungen beschrieben, die zu Planung und Bau eines Klinikums mit Deckenspannweiten von bis zu 33.6 m führten.

Deposition from a low pressure plasma beam source creates a highly tetrahedral form of hydrogenated amorphous carbon (ta-C:H)) which is analogous to the ta-C formed by deposition from a filtered cathodic arc or mass-selected ion beam. The properties of ta-C:H have been studied as a function of the substrate deposition temperatureTs and ion energy using electron energy loss spectroscopy, X-ray diffraction and atomic force microscopy. The density decreases suddenly for deposition temperatures above a threshold value, which is found to decrease with increasing ion energy. The films above the threshold are mainly sp2 bonded, with graphitic layering and high roughness. The variation of the film density with the ion energy andTs is consistent with deposition occurring by subplantation.

It is shown that small variations of the deposition parameters during magnetron sputtering of tungsten carbide thin films may result in drastic changes of film properties. An increasing working gas pressure for example lowers stress and hardness values. Simultaneously, the texture of the ß WC1-x cristallites turns from <200> preferential orientation to <111>, whereas the composition of the films does not change. In reactive sputtering with a tungsten target there is a narrow range from 2 to 3% C2H2 gas admixture to the working gas where the films are stochiometric (WC) and hard, and grain size and morphology are similar to that of non-reactively sputtered films. The generation of different crystallite structures and orientations in the range of 0–3% C2H2 admixtures are used to produce a multiphase thin film with extremely low crack propagation.

Triple differential cross sections have been measured for electron impact ionization of helium at 256 eV collision energy, 3 eV energy of the slow outgoing electrons and scattering angles of the fast outgoing electrons of 4°, 6°, 8°, and 10°. The data have been put on absolute scale by extrapolating the generalized oscillator strength to zero momentum transfer. In this optical limit the triple differential cross sections can be normalized by using the well-known cross sections for photoionization.

The semicontinuous and continuous degradation of phenol by Pseudomonas putida P8 which was immobilized on activated carbon was investigated. The amount of bacteria immobilized on the activated carbon surface dependend on the cell concentration in the suspension and on the type of activated carbon. In a continuous process running for four weeks the biomass, which accumulated in the activated carbon fixed bed, was removed periodically. The average phenol degradation rate in this process was 360 mg/1 h. The degradation activity of the bacteria for phenol, measured by the activity of the catechol-2,3-dioxygenase, was stimulated by the activated carbon. During the fermentation processes the carbon particles were covered with a biofilm. The bacteria grew, especially in the caverns and the entrances of the macropores, whereby the phenol adsorption by the activated carbon was decreased.

The phenol degradation by Candida sp. and Pseudomonas sp. immobilized on activated carbon was investigated. Thanks to its great adsorptive surface, activated carbon is suited as supporting material for microorganisms and also provides a high adsorption capacity for phenol.

Measurements are made of the inelastic scattering of electrons from methane into large scattering angles. The results show the appearance of a collision process at 19.5 ± 0.2 eV. From the measured angular dependence of the differential scattering cross section, this collision process is identified as an optically forbidden transition. The classification of this transition (2 sa1→ 3 sa1) and a value of the second appearance potential of methane (between 23.5 and 24 eV) are deduced from analogous transitions in neon.

A 60°-magnetic mass spectrometer of high sensitivity (smallest detectable signal ca. 10-19amps) has been used for the measurement of appearance potentials of high kinetic energy fragment ions from propane. The appearance potential values show that these ions originate both from singly and doubly charged molecular ions. The ions C2H5+, C2H3+, C2H2+, CH3+, CH+, H2+, and H+are produced by at least two reactions. However, only one process was found for the ions C2H4+and C2H+. The calculated and measured appearance potentials agree within some tenths of a volt. The kinetic energy was measured by the deflection method. The accuracy in the determination of appearance potentials is largely determined by the high resolution in kinetic energy measurement.

Es ist bekannt, daß die Massenspektren großer Moleküle eine sehr starke Temperaturabhängigkeit zeigen. Eine brauchbare Theorie der Massenspektren muß diese Temperaturabhängigkeit wiedergeben. In der vorliegenden Arbeit wurden die Massenspektren einer Reihe von gesättigten und ungesättigten Kohlenwasserstoffen in Abhängigkeit von der Temperatur (von 100°C bis maximal 700°C) gemessen und die Meßergebnisse im Rahmen der statistischen Theorie gedeutet. Dabei zeigt sich qualitative Übereinstimmung zwischen Theorie und Experimenten. Die quantitative Prüfung wird am Beispiel des Propans durchgeführt. Auftretende Abweichungen zwischen errechneter und gemessener Temperaturabhängigkeit des Spektrums sind möglicherweise auf die unzureichende Kenntnis der von den Elektronen beim Stoß auf die Moleküle übertragenen Anregungsenergien zurückzuführen.

Simultaneous analysis of e/m, the kinetic energies of the fragment ions, and their appearance potentials were made in order to separate dissoziative ionization processes according to the electronic states of the fragments. The energy dependencies of absolute total cross sections have been determined for three different processes leading to the formation of both energetic N+and O+-ions from N2resp. O2.

Electron scattering measurements have been made of the energy dependences of the excitation of the Helium 23S, 21S, 23p, and 21Pstates at different scattering angles in the range from 20 to 145°. In the energy range from 22 to 23 eV five overlapping resonances of the (e-He)-system have been determined, one of which (22.42 eV) is identified to be a 32S, another (22.60 eV) a 32P-state. The energy values of the other resonances are resp. 22.55, 22.75, and 22.85 eV. The half-widths are below approximately 40 meV. In the 23P-channel three peaks vanish at the same scattering angle, a fact, which seems not understandable in terms of first order resonance poles.

Energy and angular dependences for the electron impact excitation of the Helium 23S, 21S, 23P, and 21Pstates have been measured using monochromatic (0.05 eV) electrons in the energy range from 19 to 23 eV and for scattering angles ranging from 0 to 110°. The structures near the 23S-threshold have been analyzed in terms of resonant and non resonant i.e. direct scattering phase shifts. The first peak in this excitation function at 19.95 eV is mostly due to the rapid change with collision energy of the directs-wave phase of the inelastic scattering, which in turn is a consequence of the existence of the 22S-resonance at 19.3 eV. The energy position and behaviour with collision energy of the first peak at 20.7 eV in the 21S-channel is in agreement with the predictions for the existence of a virtual resonance state ofBurkeet al. A term sceme of the He−resonances with assignments of configurations is presented.

The photoelectron energy spectra produced by the impact of 584 Å photons on the gases Kr, H2, N2, O2, CO, NO and several alkanes are reported. The angular distribution of photoelectrons corresponding to the simultaneous formation of specific electronic states of the ion have been measured in the range 30°—130°. A preference for electron ejection in the direction of light propagation is shown in the formation of the electronic ground states of NO+ and O2+. Both involve the ejection of an electron from apg orbital.

The energy dependence of the elastic resonance scattering of low energy electrons from He, Ne, Ar, and N2 has been measured in the angular range from 8° to 110°. From the measurements are derived the total angular momenta and hence the configurations of the quasistationary negative ion states. The line shapes depend very strongly on the phase shifts for the potential scattering and on the interference of different partial waves. In the cases of He and Ne phase shifts are determined. The resonance structure in the elastic scattering from N2 in the energy range from 1.75 eV to about 3,5 eV seems to be due to the formation of the N2--ion in its electronic ground state with a2? configuration. The separations of its first few vibrational states are 237±10 meV, the natural half-width of these states being approximately 150 meV.

A modulated molecular beam technique has been used for the investigation of the exchange of internal energy between propane molecules and a metal surface. The temperatures of the beam oven and the metal surface were varied independently in the range from 50 to 600 ‡C. Accommodation coefficients were determined from the temperature dependence of the mass spectrum after collisions of the molecules with the surface. The absorption time of the particles is found to be less than 10-5 sec.

Zusammenfassung An einem Gasstrahl aus n-Heptan-Molekülen wurden monoenergetische Elektronen von 6 bis zu einigen 100 eV gestreut. Die Zahl der gestreuten Elektronen wurde in Abhängigkeit vom Winkel und von ihrer Restenergie mit einer schwenkbaren Gegenfeldanordnung gemessen. Der Nachweis erfolgt mit einem Multiplier und anschließender Zählanordnung.

Scattering experiments of 70 eV electrons from methane and n-heptane are described. The results, namely energy-loss spectra, and the energy and angular distributions of the ejected electrons of these molecules are compared with those of argon. A coincidence technique is used to determine the energy distributions of the probability for formation of the molecular ions. By subtraction of the distributions from the total energy-loss spectra, the distributions of the superexcited states are obtained. In the case of n-heptane, superexcited states are found up to 20 eV above the first ionization potential.

Double differential cross sections (angular distributions and energy loss spectra) have been measured of electrons after ionizing electron collisions with helium at primary energiesE0between 25 eV and about 260 eV and with argon atE0=75, 150 and 200 eV. The spectra have been measured with an energy analyzing collector system of constant transmission. It was found that for high collision energies (E0≧ 80 eV) the outgoing electrons belong to one of the two energetically well separated groups, either thefastelectrons, which are scattered mainly in forward direction or theslowelectrons which are distributed isotropically into all angles. At low primary energiesE0no separation into groups is possible. Several findings indicate the qualitative applicability of the binary collision model.

A short-lived compound state of the systeme-H2in the energy region from 13.5 to 15 eV has been investigated. It desintegrates preferably into theC1πuv=0, 1, 2, 3,... vibrational states of H2. Excitation functions and angular dependences of these states have been measured. The H2vibrational levels are situated at 13.63, 13.93, 14.20, 14.70, 14.92,... eV. The shape of the potential energy curve and the internuclear distance of the compound state should be very similar to that of theC1πuresp.D1πustate ofH2.

Results of scattering experiments with monochromatic electrons in the energy range from a few tenth of an eV to about 16 eV are reported. Below 1.8 eV collision energy no resonance structures have been found either in the total scattering (transmitted current) or in the elastic and inelastic differential cross sections. The resonances above 1.8 eV have been measured in the elastic and inelastic channels (up to vibrational quantum number?=8 of the N2-molecule) in the angular range from 10° to 110°. In the inelastic channels??2 especially the first resonance peak appears asymmetric, as predicted by calculations of the associated Franck-Condon-factors. In all inelastic channels the angular dependence (due to the pure resonance scattering) shows maxima at 0° and 90° and a minimum around 55°, probably indicating gerade-symmetry of the associated N2--state.

The energy dependence of the inelastic scattering of low energy electrons into the 23S-state of Helium has been measured for different scattering angles ranging from 7° to 110°. From the measurements are derived the total angular momenta of the resonance states. The configurations of these three resonances, due to short lived negative ion states, are 22S, 22P, and a 22D. Their energies are 19.95±0.05, 20.45±0.05 and 21.00±0.05 eV. The angular dependence of the direct excitation from 21.5 eV to 24 eV varies only slightly with the energy of the colliding electrons.