Paruzzo, Federico M.Walder, Brennan J.Emsley, Lyndon2019-08-032019-08-032019-08-032019-08-0110.1016/j.jmr.2019.06.015https://infoscience.epfl.ch/handle/20.500.14299/159526WOS:000476468100018The residual broadening observed in H-1 spectra of rigid organic solids at natural abundance under 111 kHz magic angle spinning (MAS) is typically a few hundred Hertz. Here we show that refocusable and non-refocusable interactions contribute roughly equally to this residual at high-fields (21.14 T), and suggest that the removal of the non-refocusable part will produce significant increase in spectral resolution. To this end, we demonstrate an experiment for the indirect acquisition of constant-time experiments at ultra-fast MAS (CT-MAS) which verifies this hypothesis. The combination of this experiment with the two-dimensional one pulse (TOP) transformation reduces the experimental time to a fraction of the original cost while retaining the narrowing effects. Results obtained with TOP-CT-MAS at 111 kHz MAS on a sample of beta-AspAla yield up to 30% higher resolution spectra than the equivalent one-pulse experiment, in less than 10 min. (C) 2019 Published by Elsevier Inc.Biochemical Research MethodsPhysics, Atomic, Molecular & ChemicalSpectroscopyBiochemistry & Molecular BiologyPhysicsSpectroscopysolid-state nmrultra-fast mash-1 spectraconstant timehomonuclear dipolar decouplingstate nmr-spectroscopyhigh-resolution nmrmultiple-pulse nmrcrystal-structure predictionphasecrystallographyspectraelucidationsequencesdynamicstext::journal::journal article::research article