A NEW DETECTION SYSTEM OF SATURATION TRANSFER ELECTRON-PARAMAGNETIC RESONANCE SPECTROSCOPY BY A FOURIER TRANSFORMATION TECHNIQUE

A new detection system for measurement of accurate saturation transfer electron paramagnetic resonance (ST-EPR) spectra has been developed. The principle of this system is that the EPR absorbance is recorded digitally over a wide frequency range without filtering, then processed numerically by a Fourier transformation technique without any phase sensitive detector which is used in conventional ST-EPR spectroscopy. It is possible to acquire the first and second harmonic signals at inphase and 90 degree out-of-phase simultaneously. To obtain very high accuracy of phase determination, the modulation signal is also recorded and processed digitally simultaneously. To improve the signal/noise ratio, an accumulation technique is adopted.