Improved strategies for NMR diffusion measurements with magnetization-grating rotating-frame imaging (MAGROFI)

Design and application of robust rf pulses for toroid cavity NMR spectroscopy

“…A conventional rectangular pulse thus rotates spins near the central conductor by a flip angle that is six times larger than the flip angle experienced by spins near the outer wall of the toroid resonator. This large and well-defined rf inhomogeneity of toroid probes can be exploited, e.g., in spatially resolved diffusion measurements and imaging [19,[31][32][33]. However, the large rf inhomogeneity has limited spectroscopic applications of toroid probes to relatively simple experiments.…”

Probing four orders of magnitude of the diffusion time in porous silica glass with unconventional NMR techniques

“…2), and the evaluation of diffusion coefficients can be focused on the region of interest. The compensation pulse makes up for the variable part of the preparation pulse before the grid is imaged using the rapid rotating frame imaging method [13,16]. Note that in this case the diffusion time must be defined as t diff 1 3 s 1 þ s 2 þ 1 3 s 3 ¼ const due to the presence of a third diffusion period s 3 .…”

“…It is therefore more favorable to employ the fast, single-shot variant described in Refs. [13,16]. The method consists of a series of short gradient pulses with narrow intervals in between permitting the stroboscopic acquisition of data points of the pseudo FID (see Fig.…”

“…That is, the coil geometry can be optimized for strong gradients regardless of homogeneity requirements. Favorable coil geometries to be used for diffusion measurements with the MAGROFI technique turned out to be solenoids [13], conic coils [8,14] or a toroid cavity detector [15,16].…”

Coaxial probe for nuclear magnetic resonance diffusion and relaxation correlation experiments

“…It was demonstrated that with this B 1 gradient technique, the self-diffusion coefficient of the fluid could be well-determined. A particularly interesting follow-up was the development of the toroid based NMR probe 5,7 at the Argonne National Laboratory and the University of Bonn. In this design, the RF field is well confined inside the metallic toroid container where the fluid sample is placed.…”