2 research outputs found
Local Composition for a Binary Mixture of Particles on a Three-Dimensional Ising Lattice
No full textResults from Monte Carlo (MC) simulations are reported
for a binary
mixture of particles A and B placed at the nodes of a three-dimensional
cubic Ising lattice, with pairwise nearest neighbor interactions between
species <i>i</i> and <i>j</i>, <i>E</i><sub><i>ij</i></sub>. The local composition is studied
as a function of composition and of the value of the interchange energy
(δ = 2<i>E</i><sub>AB</sub> – <i>E</i><sub>AA</sub> – <i>E</i><sub>BB</sub>). The MC results
are used to assess the accuracy of analytical theories proposed in
the literature as a function of the interchange energy. The local
composition is shown to obey an exact limiting law at high dilution
of one component, thus providing a simple expression for the limiting
activity coefficient. The activity coefficients of the species and
the entropy per particle are computed from the MC data
Influence of Strong Confinement on the Structure and Dynamics of Liquids: a Study of the Clay/Water Interface Exploiting <sup>2</sup>H NMR Spectroscopy and Spin-Locking Relaxometry
No full text<sup>2</sup>H NMR spectroscopy, multiquanta relaxation, and spin-locking
relaxometry are used to investigate the structural and dynamical properties
of water molecules confined within dense sediments of synthetic fluorohectorite.
As shown by the large residual splitting of the <sup>2</sup>H NMR
resonance line, water molecules confined in the interlamellar space
of the clay are strongly oriented to contact with the fluorinated
basal surface of the clay. Multiquanta relaxation measurements are
used to identify and quantify the contributions of the quadrupolar
and heteronuclear dipolar couplings by monitoring the NMR relaxation
of the confined water molecules. Finally, the average residence time
of the water molecules confined within the interlamellar space of
the clay platelets is quantified by detailed analysis of <sup>2</sup>H spin-locking relaxometry measurements. Thanks to the significant
contributions of both quadripolar and heteronuclear dipolar relaxation
mechanisms, <sup>2</sup>H spin-locking relaxation measurements probe
a broad dynamical range, by sampling angular velocities ranging between
10<sup>2</sup> and 3 × 10<sup>5</sup> rad/s
