An X-Band Crossed-Loop EPR Resonator

A copper X-band (9.22 GHz) cross-loop resonator has been constructed for use with 4 mm sample tubes. The Q for the two resonators is 380 and 350, respectively. The resonator efficiency is about 1 G per square root of watt. Operation has been demonstrated with measurement of T 1 by saturation recovery for samples of coal and an immobilized nitroxide.