Abstract: The ¹H MAS spectrum of fumaric acid monoetbyl ester recorded by a single pulse experiment is composed of a high resolution component and a broadline component.The high resolution component can be well separated from the broadline component using Hahn echo sequence with a long echo time.The properties of both components are investigated by variable temperature ¹H MAS and CRAMPS experiments.Two sets of resonances are observed in the CRAMPS spectrum as the temperature approaches the melting point of the sample.It is confurmed that the high resolution component is produced by a plastic phase in the solid,while the broadline component is generated by the rest of the solid,i.e., the rigid phase.The experimental resultS sufficiently demonstrate that the modern NMR techniques,¹H MAS and CRAMPS,are very useful tools for the studying of plaStic organic solids because of their enhanced spectal resolution.

Key words: Variable temperature, ¹H MAS and CRAMPS, Fumaric acid monoethyl ester, Plastic phase