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Author: search.filters.author.Schweitzer, DieterInstitute: search.filters.UBSInstitut.Sonstige EinrichtungStart date: 1979End date: 1979

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Now showing 1 - 6 of 6
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    Electronic properties of the triplet state of fluorene, carbazole, dibenzofuran and dibenzothiophene(X-traps)
    (1979) Goldacker, Wilfried; Schweitzer, Dieter; Zimmermann, Herbert
    The triplet state of X-traps in neat single crystals of fluorene, carbazole, dibenzofuran and dibenzothiophene was investigated bv the method of ODMR in zero field at 1.3 K. In addition to the intersystem crossing rates, steady state populations, decay rate constants and relative radiative rate constants of the sublevels, the spin-lattice relaxation (SLR)-rates were measured, which could not be neglected even at this low temperature. In the case of dibenzothiophene a strong intramolecular heavy-atom effect due to the sulphur atom was observed which allowed direct So → T1 excitation.
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    Transanular interaction in [2.2]phanes: models for dimers?
    (1979) Goldacker, Wilfried; Hausser, Karl H.; Schweitzer, Dieter; Staab, Heinz A.
    The emission spectra of pseudo-ortho 3 and pseudo-geminal-4,7,12,15-tetramethoxy[2.2]-paracyclophane 3 were measured in glass matrices at 1.3 K. Furthermore, the zero field splitting parameters D and E and the decay rate constants ki of the excited triplet state were studied by optical detection of magnetic resonance in zero field. The results were compared with the corresponding monomer 1,4-dimethyl-2,5-dimethoxybenzene.
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    Investigation of the excited triplet states of [2.2]- and [3.3]paracyclophane
    (1979) Melzer, Guenter; Schweitzer, Dieter; Hausser, Karl H.; Colpa, Johannes Pieter; Haenel, Matthias
    We have studied the excited triplet states of [2-2]- and [3.3]paracyclophane by emission spectroscopy and by ODMR and have compared the results with the corresponding monomer paraxylene. The most striking result is that both phanes exhibit two sets of zero field splitting parameters indicating the existence of two nearly degenerate low lying excited triplet states. Furthermore, we find in distinction to expection a stronger reduction of the zero field splitting parameters as compared to the monomers for [3.3]paracyclophane than for [2.2]paracyclophane. The causes of these surprising experimental findings are discussed.
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    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.
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    Molecular structure and spectroscopic properties of Kekulene
    (1979) Krieger, Claus; Diederich, Francois; Schweitzer, Dieter; Staab, Heinz A.
    Considerable bond localization has been detected in kekulene(1) by X-ray structure analysis: only every second ring is "aromatic". This initially surprising result is in accord with various spectroscopic properties of (1).
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    Molekülstruktur und spektroskopische Eigenschaften des Kekulens
    (1979) Krieger, Claus; Diederich, Francois; Schweitzer, Dieter; Staab, Heinz A.
    Beträchtliche Bindungslokalisation im Kekulen (1) wurde durch Röntgen-Strukturanalyse nachgewiesen: Nur jeder zweite Ring ist "aromatisch". Dieser zunächst überraschende Befund ist mit einigen spektroskopischen Eigenschaften von (1) in Einklang.