CSA-enabled spin diffusion leads to MAS rate-dependent T1's at high field

A surprisingly strong spin rate dependence of (15)N and (13)C NMR T(1) times in magic angle spinning experiments on solid peptides is demonstrated. Using a variety of isotopomers, the phenomenon is shown to be the result of chemical shift anisotropy-mediated spin diffusion. This effect has the potential to be used to detect long-range distance constraints in macromolecular systems.