A radiofrequency ESR spectrometer/imager

A Radiofrequency ESR spectrometer/imager is described. Modified from a Surrey Medical Imaging Systems NMR spectroscopy/imaging console, it uses a PC with associated waveform controller cards to perform CW ESR. Digital phase-sensitive detection is provided by a vector processor. The “target-field”-designed magnet and gradients are driven by audio amplifiers. The dual-channel broad-band RF bridge has a reflection homodyne configuration. Birdcage coils have been built that resonate near 200 MHz. Spectra and images of lossy samples of up to 4 cm diameter have been acquired.