Xe nuclear magnetic resonance line shapes in channels decorated with paramagnetic centers.

To make predictions of the Xe NMR line shapes for Xe in channels decorated with paramagnetic centers, we consider a model system using the O(2) molecule as the paramagnetic center. The previously calculated quantum mechanical Xe@O(2) hyperfine tensor for various configurations of Xe in the presence of O(2) provides a model for the hyperfine response of Xe atom to the presence of a paramagnetic center. The averaging is carried out using the same grand canonical Monte Carlo methodology as for calculating NMR line shapes for Xe in diamagnetic channels, modified to include the effects of the hyperfine tensor response. We explore the temperature dependence of the Xe line shapes, the dependence on the concentration, and the symmetry of distribution of embedded paramagnetic centers, on the orientation of the paramagnetic center axis with respect to the channel axis, and on the radial distance of the paramagnetic center from the axis of the channel. We predict Xe line shape signatures of the presence and orientation of paramagnetic centers and deduce which tensor elements provide measures of concentration and radial distance of paramagnetic centers from the channel axis.