Method and apparatus for detecting electron spin transitions in zero field

摘要

A method and apparatus for detecting spin transitions for a paramagnetic substance that are induced in the absence of a magnetic field. The method includes the steps of placing a substance under investigation in a high magnetic field. The magnetic field is then rapidly turned off and then reenergized. An ESR signal obtained after the magnetic field is reenergized is used as a baseline. This process is then repeated except that when the magnetic field strength is reduced to zero, the substance is exposed to radio frequency (rf) electromagnetic energy. Any spin transitions induced in the substance by absorption of the rf energy are detected by comparing the resulting ESR signal, detected when the magnetic is reenergized, to the baseline ESR signal.