INHOMOGENEOUS LINE-BROADENING EFFECTS IN H-1 2-DIMENSIONAL 4-PULSE ESEEM SPECTRA OF BETAINE PHOSPHITE SINGLE-CRYSTALS

The effects of inhomogeneous and homogeneous line broadening on the li neshape in two- and quasi-three-dimensional four-pulse (HYSCORE) H-1 e lectron-spin-echo-enGelope-modulation spectra in single crystals of be taine phosphite are examined. The inhomogeneous line broadening leads to a ridge-type cross-peak shape in the two-dimensional four-pulse spe ctra. Whereas the homogeneous linewidth can be directly taken from the cross peaks, spectral simulations are necessary for the determination of the inhomogeneous linewidth. The hyperfine-coupling-parameter dist ributions of protons in the hydrogen bonds of betaine phosphite single crystals are determined. The observed inhomogeneously broadened cross -peak lineshapes indicate small local random fields in the disordered paraelectric phase of betaine phosphite. (C) 1996 Academic Press, Inc.