A Signal-to-Noise Standard for Pulsed EPR

Abstract A 2 mm diameter by 10 mm long cylinder of fused SiO 2 (quartz) γ-irradiated to 1 kGy with 60 Co contains about 2 × 10 16  spins/cm 3 . It is proposed as a standard for monitoring signal-to-noise (S/N) performance of X-band pulsed EPR spectrometers. This sample yields S/N of about 25 on modern spin echo spectrometers, which permits measurement of both signal and noise under the same conditions with an 8-bit digitizer.