Hydrogen and deuterium NMR of solids by magic-angle spinning
The nuclear magnetic resonance of solids has long been characterized by very large specral broadening which arises from internuclear dipole-dipole coupling or the nuclear electric quadrupole interaction. These couplings can obscure the smaller chemical shift interaction and make that information unavailable. Two important and difficult cases are that of hydrogen and deuterium. The development of cross polarization, heteronuclear radiofrequency decoupling, and coherent averaging of nuclear spin interactions has provided measurement of chemical shift tensors in solids. Recently, double quantum NMR and double quantum decoupling have led to measurement of deuterium and proton chemical shift tensors, respectively. A general problem of these experiments is the overlapping of the tensor powder pattern spectra of magnetically distinct sites which cannot be resolved. In this work, high resolution NMR of hydrogen and deuterium in solids is demonstrated. For both nuclei, the resonances are narrowed to obtain liquid-like isotropic spectra by high frequency rotation of the sample about an axis inclined at the magic angle, ..beta../sub m/ = Arccos (3/sup -1/2/), with respect to the direction of the external magnetic field. For deuterium, the powder spectra were narrowed by over three orders of magnitude by magic angle rotation with precise control of ..beta... A second approach was the observation of deuterium double quantum transitions under magic angle rotation. For hydrogen, magic angle rotation alone could be applied to obtain the isotropic spectrum when H/sub D/ was small. This often occurs naturally when the nuclei are semi-dilute or involved in internal motion. In the general case of large H/sub D/, isotropic spectra were obtained by dilution of /sup 1/H with /sup 2/H combined with magic angle rotation. The resolution obtained represents the practical limit for proton NMR of solids.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6645809
- Report Number(s):
- LBL-14200; ON: DE83003634
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ANGULAR MOMENTUM
AROMATICS
BENZENE
CHEMICAL SHIFT
COUPLING
DEUTERIUM
ELEMENTS
HAMILTONIANS
HYDROCARBONS
HYDROGEN
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MATHEMATICAL OPERATORS
MEASURING INSTRUMENTS
MOLECULAR STRUCTURE
MOTION
NMR SPECTROMETERS
NONMETALS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PARTICLE PROPERTIES
QUANTUM OPERATORS
RELAXATION
RESONANCE
ROTATION
SOLIDS
SPECTRAL SHIFT
SPECTROMETERS
SPIN
SPIN-LATTICE RELAXATION
STABLE ISOTOPES
TENSORS