The Journal of Chemical Physics, 14 August 2006J. Chem. Phys. 125, 064507
Limin Shao and Jeremy J. Titman
An alternative magic angle spinning (MAS) exchange NMR experiment based on chemical shift anisotropy (CSA) amplification is described. The CSA amplification experiment correlates a standard MAS spectrum in the 2 dimension with a sideband pattern in 1 in which the intensities are identical to those expected for a sample spinning at some fraction 1/N of the actual rate r. In common with 2D-PASS, the isotropic shift appears only in the 2 dimension, and long acquisition times can be avoided without loss of resolution of different chemical sites. The new CSA amplification exchange experiment provides information about the time scale and geometry of molecular motions via their effect on the sideband intensities in a one-dimensional pattern. The one-dimensional patterns from different chemical sites are separated across two frequency dimensions according to the isotropic shifts.