Fig. 6.

Pulse sequence of combined DIPSHIFT and DARR experiments. After the ramped CP, a DIPSHIFT dipolar filter is applied, with a fixed ¹H–¹³C recoupling period, here shown with R18₁⁷ recoupling. Subsequently, the residual ¹³C signal (from non-rigid carbons) is allowed to evolve under incrementing t₁ periods, prior to DARR-based ¹³C–¹³C polarization exchange. This pulse sequence generates a broad-band ¹³C–¹³C spectrum, but the DIPSHIFT filter would only work fully for the ¹³C–¹H protonated carbons (CH/CH₂).