Magnitudes and Orientations of Interaction Tensors Determined from Rotational Resonance MAS NMR Lineshapes of a Four-13C-Spin System

Double-Quantum Filtration under Rotational-Resonance Conditions: Numerical Simulations and Experimental Results

“…The second most sensitive fit parameter, again for both the n ϭ 1 R 2 and the R 2 -DQF experiment, is ␤ PC23 CS2 . For this parameter, however, the sensitivity in both experiments is more than an order of magnitude less than that for b 23 . This finding for the 13 C2-13 C3 spin pair in 1-C2/C3 should not be misread in the sense that it might be generally "safe" to ignore magnitudes and orientations of chemical shielding tensors when aiming solely at the estimation of internuclear distances from R 2 or R 2 -DQF MAS NMR experiments.…”

“…For the 13 C2-13 C3 spin pair, the only parameter sensitively encoded in n ϭ 1 R 2 MAS NMR spectra is b 23 . A similar picture emerges for the R 2 -DQF lineshapes of the 13 C2-13 C3 spin pair.…”

“…Our procedures for numerically exact spectral lineshape simulations and iterative fitting are fully described and discussed in detail elsewhere, in particular addressing the n ϭ 0 R 2 condition for isolated homonuclear spin pairs (22) and various n ϭ 0, 1, 2 R 2 conditions in an isolated homonuclear 13 C four-spin system (23). In general, these numerical procedures employ the REPULSION (24) or Lebedev (25) schemes for the calculation of powder averages, implement some of the routines of the GAMMA package (26), and use, where possible, the ␥-COM-PUTE approach (27)(28)(29)(30).…”

Principles of Spin‐Echo Modulation by J‐Couplings in Magic‐Angle‐Spinning Solid‐State NMR

“…The fitted J-coupling of Table 2 J = 64.9 AE 1.8 Hz agrees reasonably well with the solution-state J-coupling estimate of J = 67 Hz. [85] Fourier transformation of s(t) provides a large central peak flanked by the two components of the J-split doublet (Figure 9 b, right column). This behaviour is consistent with the different principal axes orientations of the two large CSA tensors, which bring the spin system into Regime C of Figure 5 a (indicated by a square).…”

Orientational Information from TEDOR Spectral Sidebands

“…While the magnitude of the CS tensor principal values can be easily obtained via an analysis of the spectral sideband intensities seen in conventional 1 H-decoupled CPMAS spectra, one has to employ more sophisticated procedures for obtaining the CS tensor orientation with respect to the molecular frame. Several MAS NMR studies have been reported recently for achieving this in systems containing dipolarcoupled homonuclear spin-1/2 pairs [11][12][13][14]. The efficacy of REDOR [15,16] for obtaining CS tensor orientation has also been shown recently by Goetz and Schaefer [17].…”