Universität Stuttgart
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Item Open Access Metallic coordination polymers using CS2 as starting material(1987) Keller, Heimo J.; Klutz, Thomas; Münstedt, Helmut; Renner, Gerd; Schweitzer, DieterOrganic polymers with "metallic" properties have found widespread interest during the last few years. Acetylene and aniline as well as different nitrogen and sulfur heterocycles have been used as starting materials. One main problem hampering the technical application of these solids up to now is their environmental and thermal instability. Therefore, we introduced metal ions to stabilize polymeric backbones with high electrical conductivity. Because of the enormous coordination ability of sulfur to many transition metal ions we decided to use a polymeric carbon-sulfur backbone.Item Open Access Zukunft der Optik(1970) Tiziani, Hans J.Die Optik hat in den letzten Jahren neuen Aufschwung genommen. Mitverantwortlich für diese Entwicklung sind sowohl die Verwendung von leistungsfähigen Computern als auch die Nachfrage nach immer besserer Auflösung und Bildqualität. Besonders positiv haben sich die Entwicklungen des Laser (1960) und der Holographie ausgewirkt. Immer neue Applikationen des gebündelten, kohärenten Laserlichtes werden erschlossen, doch will ich mich in diesem Zusammenhang auf die mögliche Weiterentwlckung der erwähnten Gebiete beschränken.Item Open Access Excited electronic states of flavin-containing coenzyme models(1988) Gückel, Friedemann; Schweitzer, Dieter; Becker, Katja; Schirmer, Rolf Heiner; Zipplies, Matthias F.; Staab, Heinz A.In order to gain further insight into the physical basis of flavin-catalyzed reactions, the interactions of a flavin with a second flavin and with other aromatic ring systems were studied. For this purpose compounds through 1 were synthesized These compounds contain the interacting units in defined geometric orientation. A monomeric flavin and glutathione reductase a flavoenzyme of known active-site chemistry, were included as reference molecules. The present report deals with excited triplet states of the flavin compounds as studied by optical spectroscopy and optically detected magnetic resonances (ODMR) at 1.3K.Item Open Access Self-consistent modelling of pulsar magnetospheres(1989) Herold, Heinz; Ertl, Thomas; Finkbeiner, Bernd; Ruder, HannsThe magnetosphere of a rapidly rotating, strongly magnetized neutron star with aligned magnetic and rotational axes (parallel rotator) is modelled numerically. Including the radiation of the particles accelerated to relativistic energies as an efficient damping mechanism, we obtain a quasi-stationary selfconsistent solution to this classical problem. The numerical simulation, which was started from the well-known vacuum solution, yields a global magnetospheric structure that can be characterized by two regions of oppositely charged particles, which eventually produce a relativistic pulsar wind, separated by a vacuum gap of considerable extent.Item Open Access Optical elements for atoms : a beamsplitter and a mirror(1993) Sigel, Martin; Pfau, Tilman; Adams, Charles S.; Kurtsiefer, Christian; Seifert, Werner; Heine, Claus; Mlynek, Jürgen; Kaiser, Robin; Aspect, AlainIn the first part of this article we attempt to provide a very brief introduction to atom optics. In the second and third part we report on recent experiments in our group on two specific atom-optical elements that may be useful in atom interferometers and atom cavities: the demonstration of a new beam splitter based on the diffraction of atomic matter waves from a "magneto-optical grating" and the investigation of a mirror based on the reflection of atoms from an evanescent light field.Item Open Access Nuclear magnetic shielding tensors for 1H, 13C, and 15N in organic solids(1975) Spiess, Hans Wolfgang; Haeberlen, Ulrich; Kempf, Jürgen; Schweitzer, DieterA survey will be given of nuclear magnetic shielding tensors obtained by multiple pulse techniques for 1H in carboxylic acids and by high field NMR for 13C in carbonyl- and carboxyl groups of aromatic compounds and for 15N in pyridine and nitrobenzene.Item Open Access Resonance and relaxation attenuation by neutral acceptors in a magnetic field(1977) Schad, Hanspeter; Lassmann, Kurt; Zeile, HeinrichFine structure, level splitting, and relaxation times of the acceptor ground state in cubic semiconductors can be deduced from ultrasonic attenuation. By the application of a magnetic field it is possible to vary the coupling strength and the number of acceptors on speaking terms with the ultrasonic wave. Making use of this possibility, we have determined directly effective coupling constants for relaxation attenuation and the temperature dependence of the critical intensity for saturation of the resonant interaction. Results obtained for p-type GaAs and Si are discussed in comparison with analogous results for glasses.Item Open Access Atomic beam splitters based on light(1993) Adams, Charles S.; Pfau, Tilman; Mlynek, JürgenIn this paper we review techniques to coherently split an atomic beam using the dipole force. We discuss the interaction of atoms with normal standing wave light field in the context of atomic beam splitters. The case where the atom enters the standing wave at a small angle such that Bragg diffraction and velocity selective resonances are observed is also considered. An alternative approach to realize a coherent beam splitter based on the optical Stem-Gerlach effect is discussed. Finally we consider the interaction of atoms with a magneto-optical potential formed by a polarization gradient light field and a static magnetic field. We show that the Stem-Gerlach effect and the magneto-optical potential produce a more effective beam splitting into states with high tranverse momentum than diffraction from a normal standing wave.Item Open Access Prospects of testing aspheric surfaces with computer-generated holograms(1981) Tiziani, Hans J.For testing aspheric surfaces, computer generated holograms are frequently used. Some methods of generating the holograms as well as a comparison of in-line and off-axis computer generated holograms will be discussed. Furthermore, examples tested will be analysed from the stand point of an industrial testing procedure.Item Open Access Spectroscopic properties of kekulene(1981) Schweitzer, Dieter; Hausser, Karl H.; Diederich, Francois; Staab, Heinz A.; Vogler, HelmutKekulene [1,2] is the first example of a new class of aromatic compounds in which the annelation of six membered rings leads to a cyclic system enclosing a cavity with hydrogen atoms.