Observation of the Nonsecular Frequency Shift of the NMR Line in SolidHe3

Abstract
Observation of the nonsecular frequency shift in the NMR line of solid He3 associated with the off-diagonal elements in the dipolar Hamiltonian is reported. The method used is to look for the shift directly following a change in sample pressure. The result is in good agreement with the theory of Kubo and Tomita using published data for the spin-exchange rate.