The decrease in Δ1/2 (half-value line width) upon the nuclear magnetic saturation of non-metallic solids has been treated theoretically using a simple model in the case of the lower concentration of impurities.
Quantitative discrepancies of Tomita's results with φ≈1/T, for the case of F19 in CaF2 crystals could be removed at least by considering the suitable situation of relaxation via spin-spin interaction to paramagnetic ions. We put forth a modification of Tomita's theory by taking into an account of the 4th order effect of spin-spin interaction, and obtained a criterion about the line-narrowing rather different from Tomita's one,
W1? (σ″IIσ2I/φ0) 1/2
as the results of the motional effect of nuclear spins near impurities. This shows good quantitative agreement with the experimental data of Holcomb.
