Energy loss by electrons in DNA

The dipole oscillator strength distribution (DOSD) for dry, solid DNA was constructed from experimentally derived optical constants and X-ray attenuation cross-sections. Various energy loss parameters, including the stopping power, the inelastic mean free path and the inelastic collision cross-section, were calculated from the DOSD and stochastic Monte Carlo simulations were performed to evaluate the energy loss distribution for energetic electrons. Large differences were found between the predictions for DNA and those previously reported for gaseous media, raising serious questions about the usefulness of calculations of radiation-induced damage in DNA based on cross-sections for gaseous media.