MOLECULAR PHYSICS, 1998, VOL. 95, No. 6, 1197-1207



Cross polarization in the tilted frame:
assignment and spectral simplification in heteronuclear spin systems

Marc Baldus,1 Aneta T. Petkova,1,2 Judith Herzfeld,2 and Robert G. Griffin1

1Francis Bitter Magnet Laboratory and Dept. of Chemistry, MIT, Cambridge MA 02139
2Dept. of Chemistry and Keck Institute for Cellular Visualization, Brandeis University, Waltham MA 02454-9110



Abstract

A frequency selective heteronuclear polarization transfer technique is introduced for rotating solids. In this method, radiofrequency fields comparable with the frequency offsets are applied to establish Hartmann-Hahn cross polarization that therefore depends explicitly on the resonance offset of the nuclei involved. Under these conditions, spectrally induced filtering in combination with cross polarization (SPECIFIC CP) can be achieved and is demonstrated to be useful for spectral simplification or assignment in heteronuclear spin pairs. The design principles are outlined and demonstrated experimentally on 13C, 15N labeled amino acids.