Recombination of ion radicals in single crystals of cytosine monohydrate

Single crystals of cytosine monohydrate were irradiated with γ rays at 77 K, and the electron spin resonance (ESR) spectra were recorded while gradually increasing the temperature. The analysis of the decrease in line intensity shows that the disappearance of cation and anion radicals is due predominantly to their mutual recombination. The kinetics study clearly displayed the existence of recombination processes with several distinct groups of activation energies. It is assumed that activation energies are reduced by the Coulomb interaction of closely spaced ions. The track model for the deposition of energy during irradiation is discussed