The Role of Secondary Electrons in Radiation Damage

Abstract

In the present contribution we will show that low energy electrons (< 10 eV), which are formed as secondary species in the interaction of ionizing radiation with biological matter, can effectively damage molecules of biological matter. The underlying mechanism is dissociative electron attachment, where the transient negative ion (TNI) state decays by dissociation into a fragment anion and one or more neutral fragments. We investigated this process with building blocks of DNA (nucleobases) and proteins (amino acids). We studied these compounds under isolated conditions in the gas phase and also when they were embedded in cold helium droplets. The latter experiments allow the study of clusters of biomolecules and moreover, the effect of environment on the electron capture process and the decay of the TNI formed can be elucidated. This bears important consequences for drawing conclusions from the gas phase results to the damage of secondary electrons in a cellular environment.