Determination of New Radical Species in Ammonium Tartrate Dosimeters by CW- and Pulsed-EPR Techniques

Samples of ammonium tartrate irradiated with doses of about 0.1-1 kGy by different beams of ionizing radiation (Co-60-gamma, 19 MeV protons and 62 MeV per nucleon carbon ions) were studied by continuous-wave electron paramagnetic resonance (cw-EPR) and by pulse-EPR techniques. Careful analysis of the cw-EPR and of the echo-detected EPR spectra allowed the identification of a second radical in the system besides the already known radical formed at high temperature by an hydrogen elimination at C(2) position [M. Brustolon et al., Res. Chem. Int 4:359, 1996]. The spectrum of the radical is compatible with that of a radical obtained by hydroxyl elimination.