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  • Chemistry  (5)
  • Inorganic Chemistry  (1)
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  • 1
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemistry of Adsorbed Molecules. V. E.S.R.-Investigations of Phenyl Cations during Photolysis of Arendiazonium Salts in the Polycrystalline and the Adsorbed StateDuring photolysis of 4-NR2-substituted arene diazonium salts ground state triplets occur at low temperatures in the e.s.r.-spectra with (π)5(sp2)1 configuration in the polycrystalline as well as in the adsorbed state on SiO2. The influence of anions and the reaction order of decay processes are discussed. The decay of the aryl cations were also investigated in the presence of pyrene as π-electron donor. Reaction takes place with coadsorbed molecules and the decay mechanism changes from ionic character to radical character.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photooxidation of Leuco Dyes. XII. Time Resolved Investigations on the Photooxidation of Bis-sulfuric Acid Monoesters of Leucothioindigoid CompoundsThe photooxidation of 4, 4′-dimethyl-6, 6′-dichlorothioindigosol (1) was studied by means of laser and conventional flash photolysis. Three transients were detected and assigned to a radical R generated by homolytic splitting of one O—S-bond of the parent compound and to two further radicals which are formed from R by hydrolytic cleavage of the second ester group. The latter two radicals are in a protolytic equilibrium with each other and react, depending on the nature of the solvent by H-atom abstraction, or by disproportionation forming the leuco-thioindigoid dye or both dye and leuco dye. A mechanistic scheme is proposed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 329 (1987), S. 311-320 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Determination of the Molar Absorptivity (ε) of the Photoisomers of 3β-Hydroxy-cholest-5.7-diene (Provitamin D3)A method is described which allows the determination of the molecular absorptivity (ε) of all components in a four-component system and is applied to the ε-determination of the photoisomers of provitamin D3 (1): prävitamin D3 (2), lumisterol3 (3), and tachysterol3 (4). By means of irradiation with appropriate wavelengths the four-component system is reduced to a two- and a three-component system, respectively, and the unknown molar absorptivities are evaluated numerically or graphically.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 633-642 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photooxidation of Leuco Dyes. X. Investigation of the Photooxidation of Di-potassiumanthracene 9,10-ylene-di-sulfatePhotolysis of the title compound (DHAE) in water or ethanol produces anthraquinone and anthrone. In deoxygenated solutions 9,10-dihydroxyanthracene is detected as a long lived intermediate. Laser and conventional flash photolysis reveals three short-lived transients with lifetimes of 200 ns, 2 and 410 ms. Different temperature dependencies are observed for the fluorescence and the photolysis quantum yields. This is interpreted by two successive thermally activated processes: photohomolysis of O—S bond and escape of the radical pair from the solvent cage. The results are discussed with the help of a reaction scheme proposed for the photolysis of DHAE.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 378 (1970), S. 97-103 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigations on the extension of the diffuse reflectance spectroscopy by means of the dilution method of KORTÜM show the decisive influence of water sorption on the dilution substances, particularly on their absolute reflectance. Water sorption is investigated on alkali halides (NaCl and LiF) as dilution substances by gravimetric, thermal desorption and reflectance methods. Sorption gravimetry gives data on the quantities of adsorbed substances and the time function of adsorption processes, thermal desorption on chemical binding of adsorbed molecules and reflectance spektroscopy on the molar absorptivity of adsorbed water molecules.
    Notes: Bei Untersuchungen über die Erweiterung der quantitativen Diffusreflexionsspektroskopie auf der Basis der Verdünnungsmethode nach KORTÜM wurde als eine entscheidende Einflußgröße die Wasserbelegung der eingesetzten Matrixsubstanzen gefunden, die sich insbesondere auf den Verlauf des absoluten Reflexionsvermögens auswirkt.Die Wassersorption wird an Alkalihalogeniden (NaCl und LiF) als gut einsetzbaren Matrixsubstanzen mit sorptionsgravimetrischen, thermodesorptometrischen und reflexionsspektroskopischen Methoden untersucht. Die Sorptionsgravimetrie führt zu Aussagen über den zeitlichen Verlauf der Wassersorption und die sorbierten Mengen, die Thermodesorptionsanalyse ergibt Hinweise über die Bindungssituation des sorbierten Wassers, und aus den Reflexionsspektren bei verschiedenen Wasserkonzentrationen sind die Extinktionskoeffizienten des sorbierten Wassers zu ermitteln.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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