Abstract
Methods for studying chemical exchange in solid samples are discussed and a new two-dimensional magic angle sampling spinning experiment is introduced. The new experiment is derived from the basic two-dimensional experiment used in solution spectroscopy but it employs chemical-shift scaling during t1 to ensure isotropic evolution. Thus, one dimension contains isotropic shifts while the second contains isotropic plus anisotropic. Chemical exchange between inequivalent spins manifests itself by cross peaks. The new method is used to study slow exchange in three different compounds containing aromatic rings which undergo twofold flips.