Electron spin relaxation times for the alanine radical in two dosimeters

The spin-lattice relaxation times for the alanine radical in dosimeters were measured by long-pulse saturation recovery and by inversion recovery. The strong dependence of the recovery time constants on experimental conditions show that spectral diffusion processes contribute to enhanced relaxation rates, analogous to what was observed previously for 60Co γ-irradiated polycrystalline l-alanine. The spectral diffusion processes make it possible to run quantitative CW spectra of the alanine radical at substantially higher microwave powers than could be used in the absence of spectral diffusion processes.