Switching-angle sample-spinning NMR spectroscopy for obtaining powder-pattern-resolved 2D spectra: Measurements of 13C chemical-shift anisotropies in powdered 3,4-dimethoxybenzaldehyde

A Robust Technique for Two-Dimensional Separation of Undistorted Chemical-Shift Anisotropy Powder Patterns in Magic-Angle-Spinning NMR

“…Some methods are distortionless only for very small scaling factors (<0.1) (16), while most other CSA recoupling pulse sequences are notoriously sensitive to pulselength imperfections or off-resonance effects (18,19,22,23) or suffer from low sensitivity (24). The techniques that yield the best powder patterns require unconventional hardware for angle switching (15,17,25), for slow spinning, and/or for special rotor synchronization throughout the pulse sequence (12,20,21).…”

High-resolution NMR of anisotropic samples with spinning away from the magic angle

“…Data were collected on samples rotating at angles different from the magic angle, restricted between 0 • and 54.7 • (MAS). SAS has been used in the past to obtain similar correlations, with the constraint of one angle being the magic angle [9][10][11][12], and also in the context of Dynamic Angle Spinning (DAS) [13,14] for high resolution NMR of quadrupolar nuclei. Our goals here are quite different; we are interested in recording the full isotropic and anisotropic spectroscopic information by spinning the sample or the magnetic field around axes making angles with the static magnetic field away from the magic angle.…”

A Two-Dimensional NMR Experiment for the Study of Slow Motions in Complex Chemical Systems

“…This is given by and the complete FID at time t is again given by the sum of the elements of G(t) as in Eq. [6]. The form of this dG(t) dt Å G(iv / p) FID for the t 1 interval of the 2DCSA experiment is identical to that for the one-dimensional experiment (Eq.…”