Chemical shift powder spectra obtained by using ROtor-Directed Exchange of Orientations Cross-Polarization (RODEO-CP)

We present a new simple and robust cross-polarization (CP) scheme, called ROtor-Directed Exchange of Orientations CP (RODEO-CP), which permits to obtain undistorted chemical shift powder spectra with short contact times, i.e., when a (quasi-)equilibrium state polarization is not reached. RODEO-CP uses slow magic-angle spinning to suppress lineshape distortions caused by the orientation dependence of CP. The reliability of the method is demonstrated on a powder sample of ferrocene and RODEO-CP is shown to remove the ‘magic-angle hole’ that distorts CP spectra of non-oriented membrane-associated peptides undergoing fast rotational diffusion around the bilayer normal.