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.
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