Exploring connections between phase-modulated heteronuclear dipolar decoupling schemes in solid-state NMR

We here show a commonality in the approach to the design of prominent phase-modulated schemes used for heteronuclear dipolar decoupling in solid-state NMR. This concerns mainly two pulse phase modulation (TPPM), small phase incremental alternation (SPINAL), and swept-frequency TPPM (SWf-TPPM) schemes. SPINAL turns out to be a supercycled version of TPPM without any need for phase increments and yielding the same performance. This version of TPPM, called TPPM64, is hence easier to implement than SPINAL. We further compare TPPM64 with SWf-TPPM, another derivative of TPPM which has been shown to perform better than other contemporary heteronuclear dipolar decoupling schemes.