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  • 2000-2004  (2)
  • 1920-1924
  • 47B25  (1)
  • PACS. 33.25.+k Nuclear resonance and relaxation – 76.80.+y Mössbauer effect; other gamma-ray spectroscopy – 31.15.Ew Density-functional theory  (1)
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  • 2000-2004  (2)
  • 1920-1924
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Small perturbations of canonical systems (2000)
    Springer
    Integral equations and operator theory 38 (2000), S. 222-250 
    Details
    ISSN: 1420-8989
    Keywords: Primary 34A55 ; 47E05 ; Secondary 34B20 ; 34L05 ; 47B25
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We consider a singular two-dimensional canonical systemJy′=−zHy on [0, ∞) such that at ∞ Weyl's limit point case holds. HereH is a measurable, real and nonnegative definite matrix function, called Hamiltonian. From results of L. de Branges it follows that the correspondence between canonical systems and their Titchmarsh-Weyl coefficients is a bijection between the class of all Hamiltonians with trH=1 and the class of Nevanlinna functions. In this note we show how the HamiltonianH of a canonical system changes if its Titchmarsh-Weyl coefficient or the corresponding spectral measure undergoes certain small perturbations. This generalizes results of H. Dym and N. Kravitsky for so-called vibrating strings, in particular a generalization of a construction principle of I.M. Gelfand and B.M. Levitan can be shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01200125
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  • 2
    Electronic Resource
    Electronic Resource
    The spin-crossover complex [Fe(tpa)(NCS) 2 ] (2001)
    Springer
    The European physical journal 23 (2001), S. 463-472 
    Details
    ISSN: 1434-6036
    Keywords: PACS. 33.25.+k Nuclear resonance and relaxation – 76.80.+y Mössbauer effect; other gamma-ray spectroscopy – 31.15.Ew Density-functional theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The temperature-induced spin crossover of iron(II) in the [ Fe ( tpa )( NCS ) 2 ] complex has been investigated by nuclear forward scattering (NFS), nuclear inelastic scattering (NIS), extended X-ray absorption fine structure (EXAFS) spectroscopy, conventional Mössbauer spectroscopy (MS) and by measurements of the magnetic susceptibility (SQUID). The various measurements consistently show that the transition is complete and abrupt and exhibits a hysteresis between 102 and 110 K. The dependence of the hyperfine parameters of the high-spin (HS) and of the low-spin (LS) phase on temperature is gradual while the effective thickness (determined by the Lamb-Mössbauer factor f LM ) shows a step at the transition temperature. This step could be identified clearly because the effective thickness is measured directly by NFS. The Lamb-Mössbauer factor, the Debye temperature and the mean-square displacement of iron(II) could be determined for the HS and for the LS phase. When comparing the NIS data with the results from density functional theory (DFT), the Fe-N stretching vibrations of both LS and HS phases could be unambiguously identified and the f LM could be factorized for both phases into a lattice and a molecular part. The structural information from EXAFS and DFT geometry optimization are in reasonable agreement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100510170038
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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