OBSERVATION OF SPIN-LOCKED ELECTRON-SPIN ECHO ENVELOPE MODULATION

Electron spin echo envelope modulation (ESEEM) is observed in a coal sample utilizing a two-pulse sequence originally proposed by Hartmann and Hahn to generate a 'spin-locked echo'. It is experimentally shown that this spin-locked ESEEM (SLESEEM) is similar to three-pulse ESEEM rather than conventional two-pulse ESEEM with respect to the presence or absence of the sum and the difference frequencies, and the echo decay time. Besides, no phase-cycling is required for the SLESEEM experiment. A qualitative explanation of the new phenomena is suggested.