Magic-angle spinning electron paramagnetic resonance spectroscopy

Pulsed electron paramagnetic resonance (EPR) has been combined magic-angle spinning (MAS) to extract highly-resolved isotropic EPR signals from anisotropic powder spectra. With a self-built probe head, pulsed EPR experiments are performed during sample rotation with a spinning speed of almost 17 kHz. Analogous to the ultra-slow MAS experiment in NMR, in the MAS-EPR experiment transverse magnetization evolves at selected rotor positions, leading to an averaging of anisotropic contributions. The MAS-EPR spectrum of E1′ centers in γ-irradiated silica has been recorded, where averaging of the anisotropic g-factor leads to an isontropic resonance line of 1 MHz spectral width, comparable to EPR lines in low viscous liquids.