PULSED S-BAND ELECTRON-SPIN-RESONANCE SPECTROMETER

A computer-controlled pulsed electron spin resonance spectrometer operating at S-band (2-4 GHz) is described. The instrument is designed for the study of weak interactions between paramagnetic centers and surrounding magnetic nuclei by electron spin-echo modulation techniques. The incorporation of loop-gap resonators gives good sensitivity and allows use over the full octave bandwidth range. Free-induction decay and electron spin-echo signals at room temperature and at liquid-helium temperature are shown in selected sample types. The expected increase of the electron spin-echo modulation depths relative to X band (approximately 9 GHz) frequencies is demonstrated for proton modulation.