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Quasielastic incoherent neutron scattering studies on NH4(C6H5)4B and NaxCoO2.yH2O (x~0.28, y~1.3)
Niina Jalarvo, HMI Berlin
QENS measurements in a broad temperature range have been performed, in order to understand the dynamical properties of aromatic H-bonding in NH4(C6H5)4B and the water dynamics in superconducting NaxCoO2.yH2O (x~0.28, y~1.3).
The occurrence and the function of the aromatic H-bonds in many biological systems, like in protein-DNA interactions, make this study particularly interesting. Nevertheless, the dynamical properties of the aromatic H-bonds are not yet well understood, according to the complexity of this exotic type of H-bond. The QENS spectra of NH4(C6H5)4B were reproduced using models for local diffusive motions of the ammonium ions and the phenyl rings to explain the dynamical properties of aromatic H-bonding in this compound.
Intercalation of water in between the Na+ and CoO2 layers in NaCoO2 leads to superconductivity. The superconducting transition temperature (2K < Tc < 5K) depends on the amount of intercalated water molecules. Anyhow, the role of the water in the superconducting mechanism is still an open question. To determine the signature of the water dynamics on this novel compound, QENS measurements have been carried out. Our results show, that the chemically bounded water is diffusing inside a confined space, which has the dimension of the two nearby crystal sites.Back to Seminar Home Page
Last modified 17-January-2006 by website owner: NCNR (attn: )