Cross-polarization dynamics and spin diffusion in some aromatic compounds

1H/31P distance determination by solid state NMR in multiple-spin systems

“…The simplified angular dependence of CP (g encoding [25]) leads to a more pronounced time-domain oscillatory behavior at long times than for the REDOR dipolar-dephasing curve. However, using the simple phenomenological model treating spin diffusion as a relaxation process [26], we have verified that spin diffusion alone cannot account for the experimental data. Indeed, with this model, the oscillations of both the CP and REDOR curves are equally damped in contradiction with the experimental data.…”

Application of Rotor-Synchronized Amplitude-Modulated Cross-Polarization in a13C–1H Spin Pair under Fast Magic-Angle Spinning

“…CP matching profiles were computed by integrating numerically the Liouville-von Neumann equation for a rotating 13 C-1 H two-spin 1 2 system, as described previously (44,49), neglecting the heteronuclear J coupling, the 1 H-1 H spin diffusion process, and T 1 relaxation. The time-dependent RF fields of the AMCP sequences, 1I (t) and 1S (t), were approximated by their expansion in Fourier series.…”

Chemical shift powder spectra obtained by using ROtor-Directed Exchange of Orientations Cross-Polarization (RODEO-CP)

“…(1) as in Ref. [28] show that under these conditions the MAH is strongly attenuated by slow MAS so that the MKBE model adequately describes the experimental data (not shown). Experiments and simulations also demonstrate that RODEO-CP yields undistorted spectra at higher spinning speed when the lineshapes are observed to break up into spinning sidebands [13].…”

“…Note that we have previously used this model to account successfully for CWCP results in molecular crystals, polymers and liquid crystals [28][29][30][31]. The system is then treated as a tightly coupled IS spin pair immersed in a thermal bath consisting of the remaining protons.…”