Nuclear spin-lattice relaxation mechanisms in kaolinite confirmed by magic-angle spinning

Shigenobu Hayashi, Etsuo Akiba

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Spin-lattice relaxation mechanisms in kaolinite have been reinvestigated by magic-angle spinning (MAS) of the sample. MAS is useful to distinguish between relaxation mechanisms: the direct relaxation rate caused by the dipole-dipole interaction with electron spins is not affected by spinning while the spin diffusion-assisted relaxation rate is. Spin diffusion plays a dominant role in 1H relaxation. MAS causes only a slight change in the relaxation behavior, because the dipolar coupling between 1H spins is strong. 29Si relaxes directly through the dipole-dipole interaction with electron spins under spinning conditions higher than 2 kHz. A spin diffusion effect has been clearly observed in the 29Si relaxation of relatively pure samples under static and slow-spinning conditions. 27Al relaxes through three mechanisms: phonon-coupled quadrupole interaction, spin diffusion and dipole-dipole interaction with electron spins. The first mechanism is dominant, while the last is negligibly small. Spin diffusion between 27Al spins is suppressed completely at a spinning rate of 2.5 kHz. We have analyzed the relaxation behavior theoretically and discussed quantitatively. Concentrations of paramagnetic impurities, electron spin-lattice relaxation times and spin diffusion rates have been estimated.

Original languageEnglish
Pages (from-to)331-340
Number of pages10
JournalSolid State Nuclear Magnetic Resonance
Volume4
Issue number6
DOIs
Publication statusPublished - 1995

All Science Journal Classification (ASJC) codes

  • Radiation
  • Chemistry(all)
  • Nuclear and High Energy Physics
  • Instrumentation

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