Chemical Physics Letters, Vol.697, 29-37, 2018
Broadband MAS NMR spectroscopy in the low-power limit
We investigate the performance of broadband adiabatic inversion pulses in the high-power (short high-powered adiabatic pulse, SHAP) and low-power (single-sideband-selective adiabatic pulse, S(3)AP) RF regimes on a spin system subjected to large anisotropic interactions. We show by combined experimental results and spin dynamics simulations that when the magic-angle spinning rate exceeds 100 kHz S(3)APs begin outperforming SHAPs. This is especially true for low-gamma nuclei, such as Li-6 in paramagnetic Li-ion battery materials. Finally, we show how S3APs can be improved by combining multiple waveforms sweeping over multiple sidebands simultaneously, in order to produce inverted sideband profiles free from intensity biasing. (C) 2018 Elsevier B.V. All rights reserved.