Hydrogen and deuterium NMR of solids by magic angle spinning

Thesis/Dissertation · Fri Oct 01 00:00:00 EDT 1982

DOI:https://doi.org/10.2172/971084· OSTI ID:971084

Eckman, Richard Raymond ^[1]

---

1. Univ. of California, Berkeley, CA (United States)

The nuclear magnetic resonance of solids has long been characterized by very large spectral 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. For example, the homonuclear dipolar broadening, HD, for hydrogen is usually several tens of kilohertz. For deuterium, HD is relatively small; however, the quadrupole interaction causes a broadening which can be hundreds of kilohertz in polycrystalline or amorphous solids. 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, β_m = Arccos(3^-1/2), with respect to the direction of the external magnetic field. Two approaches have been developed for each nucleus. For deuterium, the powder spectra were narrowed by over three orders of magnitude by magic angle rotation with precise control of β. 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_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_D, isotropic spectra were obtained by dilution of ¹H with ²H combined with magic angle rotation. The resolution obtained represents the practical limit for proton NMR of solids. Theoretical and technical aspects are described in the text with comments on the application of the principles to other nuclei of interest.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Fossil Energy (FE), Clean Coal and Carbon Management
• DOE Contract Number: AC02-05CH11231; AC03-76SF00098
• OSTI ID: 971084
• Report Number(s): LBL-14200; TRN: US201003%%561
• Resource Relation: Related Information: Designation of Academic Dissertation: Doctoral Thesis; Academic Degree: Ph.D.; Name of Academic Institution: UC Berkeley
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
CHEMICAL SHIFT
DECOUPLING
DEUTERIUM
DILUTION
HYDROGEN
LINE BROADENING
MAGNETIC FIELDS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
POLARIZATION
PROTONS
QUADRUPOLES
RESOLUTION
ROTATION
SPECTRA
SPIN