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  • 1975-1979  (5)
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Material
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Year
  • 1
    Electronic Resource
    Electronic Resource
    THE CONSTRUCTION OF COSPECTRAL COMPOSITE GRAPHS (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 319 (1979), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Notes: An operation loosely described as a type of composition of graphs is studied. Under rather flexible conditions, the resulting composite graphs must be cospectral. This operation is sufficiently powerful to generate eighty-one cospectral pairs with at most nine vertices. These pairs include the unique smallest cospectral pair, the smallest cospectral connected pair, and one pair of trees with nine vertices. It is felt that this operation provides a unified explanation of cospectrality in several cases that were previously viewed as coincidental.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1979.tb32826.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Fourier transform nuclear magnetic resonance studies of199Hg (1975)
    Springer
    The European physical journal 273 (1975), S. 325-330 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract 199Hg Fourier Transform NMR studies of various solutions of diverse mercury salts in H2O and D2O or in the appropriate protonated and deuterated acids are reported for both Hg 2 ++ and Hg++. In the different solutions investigated the199Hg line positions depend on the concentration of the solution, on the solvents and their isotopic composition and on the temperature of the sample. A ratio of the Larmor frequency of199Hg and of2H in a Hg(NO3)2 solution in dilute DNO3 is given. Using this ratio and the measured chemical shifts, a ratio of the Larmor frequencies of199Hg for infinite dilution relative to2H in pure D2O is given. From this a gI-factor for199Hg is derived and compared with the gI-factor of an optical pumping experiment. The resulting shielding constant is σ* (hydrated199Hg++ versus199Hg atom)=−24.32(5) · 10−4. This yields an atomic reference scale for all measured NMR line shifts of mercury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01435574
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    89Yttrium nuclear magnetic resonance studies (1977)
    Springer
    The European physical journal 280 (1977), S. 117-123 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract With a Fourier-transform spectrometer, especially developed for nuclei with weak NMR signals, the lines of89Y have been investigated in aqueous solutions of Y(NO3)3, YCl3, and Y(ClO4)3. The concentration dependence of the chemical shifts of the89Y resonance frequencies in these solutions were measured. Using this dependence, the Larmor frequency of the89Y3+ ion solely surrounded by water was determined by extrapolation. The Larmor frequency of89Y was referred to those of2H,39K, and73Ge with high accuracy. The magnetic moment of the89Y3+ ion purely surrounded by H2O molecules is μ(89Y3+) = −0.1368523(4) μN. The concentration dependence of Y(NO3)3 solutions in D2O yields the solvent isotope effect δ(89Y3+ in D2O)−δ(89Y3+ in H2O)= −(4.3±0.5)ppm. The89Y relaxation times T1 and T2 of a 3 molal aqueous Y(NO3)3 solution were determined in the pH range −0.5...+1.25. T1 190...90 s is nearly constant in this range, whereas the transverse relaxation rate T2 −1 increases strongly with increasing pH; this effect seems to be due to the chemical exchange of the hydrated Y3+ ion between a monomer and a polymer site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01409538
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  • 4
    Electronic Resource
    Electronic Resource
    183Tungsten NMR studies (1975)
    Springer
    The European physical journal 20 (1975), S. 75-80 
    Details
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract With a Fourier-transform spectrometer, especially developed for nuclei with weak NMR signals, the signal of183W in a liquid diamagnetic sample was detected for the first time. The183W Larmor frequencies and chemical shifts of WF6, of [WO4]− - in aqueous solution, and of WCl6 dissolved in CS2 were determined with high accuracy. The183W resonance is referred to that of the proton in H2O and the magnetic moment of183W in WF6 isµ=0.116224 5 (7)µ N. The scalar coupling constant in WF6 was determined: |J(183W−19F)|=(40.7±1.5) Hz; an upper limit for the coupling constant |J(183W−17O)| in the [WO4]− - ion is given. The relaxation timesT 1 andT 2 of the183W resonance in WF6 were measured by steady state techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01313915
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  • 5
    Electronic Resource
    Electronic Resource
    The ratio of the quadrupole moments of the isotopes95Mo and97Mo (1975)
    Springer
    The European physical journal 274 (1975), S. 87-90 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The spin-lattice relaxation timesT 1 of the NMR signals of95Mo and97Mo in aqueous K2MoO4 solutions were determined by the inversion recovery technique. To separate the relaxation rates due to electric quadrupole interaction and due to magnetic dipole interaction, pure H2O and mixtures of H2O and D2O were used as solvent. No dependence of the ratio of the relaxation ratesT 1(95Mo)/T 1(97Mo) on the composition of the solvent was to be detected, i.e. the relaxation due to magnetic dipole interaction may be neglected. From the ratio of the relaxation rates the absolute value of the ratio of the quadrupole moments of the molybdenum isotopes was evaluated: ¦Q(97Mo)/Q(95Mo)¦ = 11.4 ±0.3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01408457
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    Paper (German National Licenses)
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