DISTORTION-FREE ELECTRON-SPIN-ECHO ENVELOPE-MODULATION SPECTRA OF DISORDERED SOLIDS OBTAINED FROM 2-DIMENSIONAL AND 3-DIMENSIONAL HYSCORE EXPERIMENTS

Simulations and experiments show that ESEEM spectra of disordered solids with S = 1/2 and I = 1/2 can be obtained free of dead-time artifacts and suppression effects by 2D and 3D HYSCORE experiments. The nuclear-larmor-frequency dependence of a suppression effect related to pulse separation is demonstrated by H-1 and C-13 spectra in a 3D experiment. Extremely broad powder lines of 10 and 5 MHz width due to H-1 and naturally abundant C-13 nuclear spins, respectively, could be observed in a coal sample, virtually free of any distortions. The interpretation of the HYSCORE correlation patterns of disordered solids is given through simulations. (C) 1994 Academic Press, Inc.