Universität Stuttgart
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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 Energy relaxation and intervalley relaxation of hot electrons in n-type germanium(1966) Seeger, Karlheinz; Schweitzer, DieterThe average current density in n-type germanium subjected to superimposed strong ac and weak dc electric fields was both measured and calculated for frequencies of 9 and 35 GHz. Repopulation relaxation of the conduction band valleys and energy relaxation were taken into account. Experimental and theoretical result agree qualitatively.Item Open Access ODMR of phanes and charge transfer phanes(1979) Schweitzer, Dieter; Goldacker, Wilfried; Hausser, Karl H.; Staab, Heinz A.Triplet zero field splitted parameters |D| and |E| and decay rates ki of the triplet sublevels of two stereoisomeric tetramethoxy [2.2] paracyclophanes as well as those of two CT [2.2] paracyclophanes in low concentration in glasses and small neat single ctystals as measured by ODMR in zero fields at 1,3 K are presented.Item Open Access Dynamic nuclear polarisation in p-doped silicon by microwave ultrasonics(1969) Hausser, Karl H.; Schweitzer, DieterWe have investigated the dynamic nuclear polarisation (DNP) of 29 Si nuclei in highly doped silicon single crystals. The saturation of the electronic Zeeman levels in a magnetic field of 3.3 kG at 1.6°K was obtained using microwave ultrasonics of about 9 GHz. The ultrasonic waves were generated in a cavity by means of a transducer consisting of a thin film of CdS evaporated on the polished surface of the silicon. Preliminary results obtained with a silicon-rod of 2 x 2 x 12 mm cut with the long axis parallel to the (110) direction rendered a reduction of the NMR signal to about ⅓ in agreement with the expected negative sign of the DNP.Item Open Access 15N and 13C spin lattice relaxation in neat liquids at high magnetic fields(1975) Schweitzer, Dieter; Spiess, Hans WolfgangGeneral features of 15N spin lattice relaxation in nitrobenzene, pyridine and triethanolamine are discussed and compared with l3C relaxation mechanisms.