Fast adiabatic pulses for solid-state NMR of paramagnetic systems

We present a simple framework for determining the parameters for efficient adiabatic pulses in solids with very large shift anisotropies under very fast MAS. We introduce the notion of the effective adiabatic quality factor to describe the spin dynamics. We then demonstrate the use of short, high-power adiabatic pulses (SHAPs) for population inversion in paramagnetic solids, and show its application to various systems with differing proton anisotropies in iron, ytterbium, and terbium complexes, from 400 to more than 1000 ppm. We then show how these pulses yield improvements in refocusing schemes and TEDOR NMR experiments on paramagnetic solids.