COMPARISON OF CONTINUOUS WAVE AND RAPID SCAN X-BAND ELECTRON PARAMAGNETIC RESONANCE OF IRRADIATED CLIPPED FINGERNAILS

摘要

X-band rapid scan electron paramagnetic resonance (EPR) measures the free radicals in irradiated clipped fingernails with higher signal-to-noise (SIN) and lower standard deviation of the signal amplitude for replicate measurements than does conventional continuous wave (CW) EPR in the same measurement time. For a clipped fingernail sample irradiated to 10 Gy and data acquisition time of 30 s with B_1 = 8.5 μT, the SIN for rapid scan is >2000 for the absorption spectrum and 1200 for the corresponding first derivative. The standard deviation for replicate measurements of signal amplitude is ～1%. For CW spectra, the SIN depends on the modulation amplitude. The CW signal has a first derivative peak-to-peak linewidth of 0.95 mT. For 30s of CW acquisition time, the SIN was 30 for a conservative modulation amplitude of 0.2 mT and B_1 of 2.3 μT or 90 for a modulation amplitude of 0.4 mT and B_1 of 3.2 μT, which resulted in standard deviations of replicate measurements of 5% or 2%, respectively.