Figure 41.

RF pulse schemes used for selective recoupling of ¹H–¹H interactions in fully protonated samples. (a) BASS-SD mixing with RF offset applied at the center of the amide proton frequency band (selection of other frequency bands, such as α or methyl protons is also possible). Panel (b) shows the SPR scheme, which is reminiscent of CN symmetry-based sequences, with a 90° pulse as a basic element (gray and black rectangles). SPR was further generalized for arbitrary phases (pSPR) and unrestricted phase incrementation, resulting in the identification of the MODIST sequence.