A transient nuclear Overhauser effect (NOE) makes measurements of the 13C spin-lattice relaxation times in organic solids complicated. Extended Solomon equations are applied in order to describe 13C spin-lattice relaxation with 1H r.f. field irradiation. Spin-lattice relaxation under r.f. irradiation is shown to be generally a triple-exponential process, but it can be reduced to be single-exponential under stronger r.f. field irradiation as well as in the absence of 1H initial magnetizations. Based on numerical calculations, the difference between spin-lattice relaxation curves obeying TC1 < TH1 and those obeying TC1 > TH1 is clearly indicated. The methyl group resonances in solid-state L-valine are examined, and the experimental results agree well with the theoretical results.
- C spin-lattice relaxation
- Extended Solomon equations
- H r.f. Field irradiation
- Transient nuclear Overhauser effect
ASJC Scopus subject areas
- Nuclear and High Energy Physics