A paper published by some of the present authors showed an unexpected doublet structure in the rigid-lattice proton magnetic resonance spectra of $\mathrm{Y}{\mathrm{H}}_3$ and $\mathrm{Lu}{\mathrm{H}}_3$. In the present study accurate spectra which contain no doublet features are obtained for $\mathrm{Y}{\mathrm{H}}_{2.96}$ and $\mathrm{Lu}{\mathrm{H}}_3$ using the technique of magic echoes. It is shown that the original spectra were distorted by time shifting of the time-domain data. The applicability of using magic echoes with these two systems is justified theoretically and by comparison to free induction decays. The measured second moments of the present spectra agree well with values predicted by the Van Vleck formula, demonstrating that the broadening of the present spectra is almost entirely dipolar.

• Received 14 July 2005

DOI:https://doi.org/10.1103/PhysRevB.72.214111