Rotational echo double resonance without proton decoupling under fast spinning condition

We show that rotational echo double resonance (REDOR) experiments can be carried out without proton decoupling under the conditions of fast spinning and strong rf field. Numerical simulations on a five-spin systems show that no significant attenuation of the reference signal (S0) is observed at a spin rate of 25 kHz, provided that the rf power is larger than 100 kHz. This approach has been validated by 31P{13C} REDOR measurements on isotopically labeled glyphosate. The obtained van Vleck's second moment is in favorable agreement with the value calculated based on the crystal structure.