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  • 1970-1974  (12)
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  • 1
    Electronic Resource
    Electronic Resource
    Kernmagnetische Relaxation in Polyisopren (1970)
    Springer
    Colloid & polymer science 241 (1970), S. 937-942 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary The temperature dependence of the longitudinal proton relaxation timeT 1 in solid and swelled cispolyisoprene (natural rubber) shows in the range between −195°C and +150°C at the Larmor frequencies 4, 22, 44 and 86 MHz two well separated minima, which can be ascribed to two kinds of chain segment motion with different activation energies. The high-temperature minimum is interpreted by kink jumps and the low-temperature minimum by methyl-group rotation. In both cases one has to assume aCole-Davidson distribution of jumping times.
    Notes: Zusammenfassung Die Temperaturabhängigkeit der longitudinalen ProtonenrelaxationszeitT 1 in festem und gequollenem cis-Polyisopren (Naturkautschuk) zeigt zwischen −195°C und +150°C bei den Larmorfrequenzen 4, 22, 44 und 86 MHz zwei deutlich getrennte Minima, die zweierlei Kettenbewegungen mit unterschiedlichen Aktivierungsenergien zuzuordnen sind. Das Hochtemperaturminimum läßt sich durch Kinkumlagerungen, das Tieftemperaturminimum durch Methylgruppen-rotation beschreiben. In beiden Fällen muß eine Sprungzeitverteilung nachCole-Davidson eingeführt werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02137399
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  • 2
    Electronic Resource
    Electronic Resource
    Kernrelaxations-Untersuchung der Selbstdiffusion in festem Kupfer (1974)
    Springer
    The European physical journal 270 (1974), S. 319-327 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report on measurements of the63Cu nuclear spin relaxation time in the rotating frame,T 1ρ, in solid copper as a function of temperature and Larmor frequency, from which the temperature dependence of the self-diffusion coefficient was evaluated using Torrey's theory. Within the relatively small temperature range (572 °C ≦ ϑ ≦ 838 °C) in which diffusion relaxation dominates, the temperature dependence of the diffusion coefficient is compatible with a simple Arrhenius law. However, in an evaluation including recent tracer results in an essentially larger temperature range (353 °C≦ϑ≦1079 °C) clear deviations from this standard interpretation were found, as implied by Seeger's divacancy formalism. From those deviations we have calculated a more reliable set of diffusion parameters than comparable data in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01677768
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  • 3
    Electronic Resource
    Electronic Resource
    Kernmagnetische Relaxation in festem Polypropylen (1970)
    Springer
    Colloid & polymer science 236 (1970), S. 129-137 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary Measurements of the temperature dependence of the proton relaxation timeT 1 in isotactic polypropylene at 4, 30, 44 and 86 Mc/s in the range between 100 °K and 430°K yielded W-shaped curves with frequency dependent high- and low-temperature minima. We discuss jump models for chain and methylgroup motion within the amorphous and cristalline regions of polypropylene which can quantitatively describe the relaxation. In both cases it is necessary to assume a jump model with a distribution (Cole-Davidson) of correlation times.
    Notes: Zusammenfassung Die Messung der Temperaturabhängigkeit der ProtonenrelaxationszeitT 1 in isotaktischem Polypropylen zwischen 100 °K und 430 °K bei den Larmorfrequenzen 4, 30, 44 und 86 MHz ergab W-förmige Kurven mit deutlich getrennten, frequenzabhängigen Hoch- und Tieftemperaturminima. Es werden Sprungmodelle für Kettenumlagerungen und Methylgruppenrotationen in der amorphen bzw. kristallinen Phase des Polypropylens diskutiert, die dieses Verhalten quantitativ beschreiben. In beiden Fällen muß ein Sprungmodell mit Korrelationszeitverteilung (Cole-Davidson) angenommen werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02086626
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  • 4
    Electronic Resource
    Electronic Resource
    Kernmagnetische Relaxationsspektroskopie an Polyäthylenglykolen (1971)
    Springer
    Colloid & polymer science 247 (1971), S. 811-813 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary The Larmor frequency dependence of the proton spin relaxation time in aqueous (D2O) solutions of polyethylene glycol 30000 shows in the range between 3 kHz and 120 MHz, in contrast with the related monomer, two well-resolved dispersion steps. This observation indicates two motional mechanisms similarly as recently demonstrated in biopolymer solutions.
    Notes: Zusammenfassung Die Larmorfrequenzabhängigkeit der ProtonenspinrelaxationszeitT 1 in wäβrigen (D2O) Lösungen von Polyäthylenglykol 30000 zeigt im Bereich zwischen 3 kHz und 120 MHz, im Gegensatz zum zugehörigen Monomer, zwei getrennte Dispersionsstufen. Diese Beobachtung deutet, ähnlich wie es vor kurzem in Biopolymeren nachgewiesen wurde, auf zweierlei Bewegungsmechanismen hin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01500252
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  • 5
    Electronic Resource
    Electronic Resource
    Proton spin relaxation in hexagonal ice (1971)
    Springer
    The European physical journal 246 (1971), S. 91-96 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the rotating frame proton spin relaxation timeT 1p in hexagonal ice single crystals as a function of temperature ϑ for various rotating magnetic field strengths reveal the expectedT 1p minimum at the lowest practicable field values. This allows a very precise determination of the proton correlation (≜ molecular jump) time τc and the related activation energy ΔE by means of the theoretical reasoning of relaxation spectroscopy. We find the Arrhenius-law temperature dependenceτ c=1.99×10−17exp(0.603/8.61×10−5 ϑ)sec, which is in good agreement with our earlier indirect derivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01402654
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  • 6
    Electronic Resource
    Electronic Resource
    Zur Deutung der Protonenspinrelaxation in Glycerin (1971)
    Springer
    The European physical journal 246 (1971), S. 84-90 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In contrast with the usual assumption that proton spin relaxation in glycerol originates from rotational molecular diffusion, quantitative evaluation of the temperature and Larmor frequency dependence in the ranges −30 °C to+70 °C and 10 kHz to 120 MHz, respectively, gives extensive agreement with Fick's translational random walk model. This observation is supported by direct measurements of the self-diffusion constant by means of the pulse gradient method, which reveals the same activation barrier as relaxation spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01402653
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  • 7
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    Zur Deutung der Protonenspinrelaxation in Glycerin (1971)
    Springer
    Details
    Publication Date: 1971-02-01
    Print ISSN: 0939-7922
    Electronic ISSN: 1431-5831
    Topics: Physics
    Published by Springer
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  • 8
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    Kernrelaxations-Untersuchung der Selbstdiffusion in festem Kupfer (1974)
    Springer
    Details
    Publication Date: 1974-12-01
    Print ISSN: 0939-7922
    Electronic ISSN: 1431-5831
    Topics: Physics
    Published by Springer
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  • 9
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    Proton spin relaxation in hexagonal ice (1971)
    Springer
    Details
    Publication Date: 1971-02-01
    Print ISSN: 0939-7922
    Electronic ISSN: 1431-5831
    Topics: Physics
    Published by Springer
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  • 10
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    Kernmagnetische Relaxation in Polyisopren (1970)
    Springer
    Details
    Publication Date: 1970-11-01
    Print ISSN: 0372-820X
    Electronic ISSN: 1435-1536
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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