A novel approach to quadrupolar-echo (QE) NMR of half-integer quadrupolar nuclei in static powders is analyzed. By acquisition of the QE spectrum during a Carr−Purcell−Meiboom−Gill (CPMG) train of selective π pulses, the second-order quadrupolar line shape for the central transition is split into a comb of sidebands leading to a considerable increase in the sensitivity compared to a conventional QE spectrum. The applicability of the method for determination of magnitudes and relative orientation of chemical shielding and quadrupolar coupling tensors is examined. Through numerical simulation and iterative fitting of experimental 87Rb (RbClO4 and RbVO3) and 59Co spectra (Co(NH3)5 Cl3), it is demonstrated that the quadrupolar CPMG experiment represents a useful method for studying half-integer quadrupolar nuclei exhibiting large quadrupolar coupling combined with anisotropic chemical shielding interactions. Sensitivity enhancements by a factor of up to about 30 are observed for the samples studied.

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Sensitivity-Enhanced Quadrupolar-Echo NMR of Half-Integer Quadrupolar Nuclei. Magnitudes and Relative Orientation of Chemical Shielding and Quadrupolar Coupling Tensors

Deuterium quadrupole-echo NMR spectroscopy. III: Practical aspects of lineshape calculations for multiaxis rotational processes

Effects of jump dynamics on solid state nuclear magnetic resonance line shapes and spin relaxation times.

Deuterium Relaxation In Molecular Solids

We describe several two-dimensional NMR experiments to facilitate the analysis of overcrowded proton-decoupled deuterium spectra of chiral molecules oriented in poly-A-benzyl-L-glutamate liquid crystalline solutions. These 2D NMR experiments allow the correlation between the components of each quadrupolar doublet in the deuterium spectra and then their assignment on the basis of chemical shift. The 2D pulse sequences proposed in this work were developed using the Cartesian spin-operator formalism for spin I ) 1 nuclei with a small quadrupolar moment, such as deuterons in high magnetic field. The features and analytical potentialities of each pulse sequence are discussed and compared. Illustrative applications of these sequences in natural abundance deuterium NMR spectroscopy using a 9.4 T magnetic field and standard NMR equipment are reported and examined. With this technique, it is demonstrated that quantitative measurements are possible within a precision of 10%.

Two-Dimensional Deuterium NMR Spectroscopy of Chiral Molecules Oriented in a Polypeptide Liquid Crystal: Applications for the Enantiomeric Analysis through Natural Abundance Deuterium NMR

Thomas M Barbara

Papers

Deuterium quadrupole echo NMR spectroscopy. I. Effects of chemical exchange during single and composite pulses

Analytical expressions and lineshape simulations for Levitt-Suter-Ernst composite-pulse quadrupolar echo sequences

2H NMR lineshapes in deuterium molybdenum bronze 2H1.66MoO3