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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 91 (1966), S. 107-120 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyethyleneoxides (HO(—CH2—CH2—O—)nH) of molecular weights 2000, 4000, and 20000 were irradiated in vacuo at 14 °C. by 1 MeV electrons. The radiation induced reactions were determined by measurements of gel and viscosity, by IR-spectroscopy, gaschromatography and bromination. Two reactions correspond to the radiation induced reactions of polyethylene, and additionally two degradation reactions occur. The degradation reactions show the influence of oxygen in the molecular chain of polyethyleneoxide. This may be compared with the degradation under external oxygen.
    Notes: Es wurden Polyäthylenoxyde (HO(—CH2—CH2—O—)nH) der Molekulargewichte 2000, 4000 und 20000 mit 1-MeV-Elektronen im Vakuum bei 14 °C bestrahlt. Durch Kombination von Gel-Sol-Messungen, Viskositätsmessungen, UR-Untersuchungen, Bromierungsexperimenten und Gasanalysen konnten die strahlungsinduzierten Reaktionen geklärt werden. Es treten beim Polyäthylenoxyd zwei Reaktionen auf, die den bei Polyäthylen gefundenen Reaktionen entsprechen, und darüber hinaus noch zwei reine Abbaureaktionen, die den Einfluß des Sauerstoffs in der Molekelkette des Polyäthylenoxyds kennzeichnen. Dieser Abbaueffekt korreliert mit der bekannten abbauenden Wirkung des äußeren Sauerstoffs.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 51-55 
    ISSN: 1057-9257
    Keywords: MOVPE ; Quantum wells ; ZnSe/ZnSxSe1 - x heterostructures ; Gain ; Excitons ; Luminescence dynamics ; Transfer processes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Optically pumped stimulated emission in ZnSe/ZnSxSe1 - x heterostructures grown by MOVPE has been observed up to 170 K. Gain measurements have been performed using the variable stripe length method. The underlying gain mechanism at 25 K is atributed to an excitonexciton scattering process. Photoluminescence excitation spectra and the temporal evolution of the luminescence indicate a transfer process from the ZnSxSe1 - x barrier into the ZnSe active layer.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 3 (1994), S. 141-150 
    ISSN: 1057-9257
    Keywords: Semiconductor-doped glasses ; Non-linear optical materials ; Differential absorption spectroscopy ; Scattering processes ; II-VI compounds ; Quantum dots ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: By use of differential absorption spectroscopy at different temperatures we investigate the homogeneous line broadening of small CdSxSe1 - x quantum dots embedded in glass. Our experiments show the strong correlation between the precipitation stages and characteristics optical parameters such as the saturation intensity and the longitudinal and transverse relaxation times. In samples grown in the diffusion-controlled regime to avoid coalescence, we find after strong laser excitation for the first time spectrally narrow holes in the non-linear differential absorption spectra. These sharp non-linear resonances with a halfwidth Γ of only 10 meV at T = 20 K allow us to investigate the energetic distance of the lowest hole levels and the temperature dependence of the line broadening. The different contributions of LO phonon coupling and temperature-independent scattering to the homogeneous linewidth will be analysed. The relaxation from the excited hole states has been investigated by exciting in the higher-energy hole states and measuring the resulting change in the ground state absorption.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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