A Comparison between REDOR and θ-REDOR for Measuring C–D Dipolar Interactions in Solids

¹³C-observe REDOR and θ-REDOR experiments for recovering the ¹³C–²D dipolar interaction during MAS NMR are compared. It is found that limited ²D RF power may severely compromise the performance of the REDOR experiment whereas the θ-REDOR experiment can be designed to work well. Results are presented for an isolated ¹³C–²D spin pair with a large deuterium quadrupolar coupling constant and for a ¹³C coupled to three methyl deuterons undergoing fast methyl group rotation.