A radiofrequency (220-MHz) Fourier transform EPR spectrometer

Radiofrequency continuous wave EPR spectrometers for detecting and localizing free radicals in vivo in samples of 50-100 g have been developed. The main limitation of these EPR instruments is the slow acquisition time, and a sensible improvement is expected by the adoption of pulsed EPR techniques. We present here a Fourier transform EPR spectrometer operating at 220 MHz suitable for large volume samples (up to 50 ml). A detailed description of the transmitter and receiver sections, including the EPR resonator, is given. Representative free induction decay data obtained from a sample with a relaxation time of about 900 ns are reported. (C) 1998 Academic Press.