Radiation damage to DNA

Our goal is to calculate the probability to eject electrons from DNA by charged particles that pass near the macromolecule as they slow down in an aqueous medium that contains DNA in low concentration. This process is illustrated for a particle of charge Ze and velocity v, where impact parameters b1, b2, and b3 indicate the distances between the trajectory and a phosphate group, a base, and a sugar moiety, respectively. In the present state of our theoretical development, we must treat each of these components of DNA as an independent impurity site occupied by electrons in a Slater-type orbital with a characteristic orbital radius and band gap. Determination of these parameters will be discussed below; however, before we turn to that part of the discussion, it is interesting to address the question of multiple ionizations of DNA by the passage of a single charged particle