ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 65.40.−f  (2)
  • 74.30.Gn  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 20 (1991), S. 329-331 
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 65.40.−f
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Specific-heat measurements on the cluster compound Au55(P(C6H5)3)12Cl6 at temperatures 0.06 K ≤T≤3 K and in magnetic fields 0≤B≤6 T are reported. While above 0.6 K the specific heatC is dominated by the inter-cluster vibrational contribution observed previously, an anomalous increase ofC towards lowT is observed below 0.3 K, withC ∼T −2. This contribution develops into a Schottky-like anomaly forB≥0.4 T, indicating that it might be attributed to local moments which are also observed in ESR measurements. From the height of the anomaly one can infer that approximately one tenth of the Au55 clusters carry a magnetic moment. For 0.6 K≤T≤1 K andB=0 our data indicate the absence of a linear electronic specific-heat contribution expected for bulk Au. This possibly constitutes the first direct observation of the quantum-size effect on electronic energy levels in the specific heat.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1434-6079
    Keywords: 74.30.Gn ; 74.70.Vy ; 76.60.Es
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract 195Pt NMR on the organic ligand stabilized metal cluster compound Pt309Phen 36 * O30 reveals two separate peaks in the lineshape. Ligand-bonded platinum atoms at the surface of the core are thought to be responsible for the peak that does not show any Knight shift. The corresponding spin-lattice relaxation timeT 1 is of the order of seconds. The second peak is Knight shifted and is attributed to the other Pt atoms, for which metallic behavior is inferred from the temperature dependence ofT 1. The Korringa relation holds down to 65 K. Below 65 K the relaxation of the magnetization becomes increasingly non-exponential with decreasing temperature. The relaxation process can be successfully modelled under the assumption of a Poisson distribution of the energy levels around the Fermi energy (the electronic quantum size effect).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1434-6079
    Keywords: 74.30.Gn ; 74.70.Vy ; 76.60.Es
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract 13C and31P solid state NMR measurements on the organic ligands in ligated Au55, Ni8, Pt309, Cu36 and Cu70 clusters are reported. The ligands behave like diamagnetic organic molecules, giving rise to relatively narrow lines with excellent cross-polarization efficiency. The resonance lines of the nuclei directly bound to the metal core are systematically broadened in the conducting compounds. No pronounced Knight shifts or evidence of metallic-like relaxation were observed. These results support a model for the electrical conduction involving tunneling between metal cores with the ligands playing the role of a tunneling barrier.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 65.40.−f ; 76.80.+y
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract There are 5 different Au-sites in the Au55 core of Au55(PPh3)12Cl6. The 13 inner atoms are almost identical to that of bulk gold. At the surface the attachment of the ligands is responsible for further differentiation. We have calculated the low temperature specific heat using the Mössbauer determined electrical quadrupolar splitting of the surface atoms. Due to too long a quadrupolar relaxation time, no such contribution is seen in the zero field results (down to 0.06 K) of Goll et al., Z. Phys. D 20, 329 (1991). The latter zero and in-field data are interpreted as the contribution of an electronic spin, hyperfine coupled to a nuclear spin 3/2. The effective abundance is about one spin per ten clusters.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...