An ESR/NMR resonator for hybrid imaging system was fabricated. It consisted of an ESR resonator, a bridged loop-gap resonator (inner diameter,43 mm; axial length,10 mm), and an NMR resonator, an LC circuit of a solenoid coil (inner diameter,60mm; axial length,10 mm) and variable capacitor. The former was located inside the latter. The resonant frequencies of ESR and NMR were 730 and 27 MHz, respectively. An ESR/NMR hybrid spectrometer was constructed for homodyne detection and lock in detection of ESR and NMR signals. By using the ESR/NMR resonator and spectrometer, CW-ESR, CW-NMR, and pulsed NMR measurements of a phantom that included a physiological saline solution containing a nitroxide radical could be made at the magnetic field of 26 mT and 640 mT.
