Theory of NMR Line Shapes in Dipolar-Broadened Spin Systems and Applications to SrF2, CsF, and NaCl

Detailed line-shape measurements of fluorine resonance in Sr${\mathrm{F}}_2$ have been made and the results compared with theories of dipolar broadening and with Barnaal and Lowe's data from Ca${\mathrm{F}}_2$. It was recognized that the theoretical results of Evans and Powles (EP) and of Lee, Tse, Goldburg, and Lowe (LTGL) were derived from the same basic expansion for the free-induction-decay function. This made it appropriate to combine their results in order to obtain an improvement in the theory. The combined result was compared with experimental data of LTGL from NaCl and with Hutchins and Day's results from CsF. In most cases, the combined result gave as good or better agreement than either the approximation of EP or that of LTGL.