Inelastic interactions of low-energy electrons with biological media

A study of inelastic interactions of low-energy electrons with biological media is of fundamental importance in the understanding of radiation-induced actions leading to the biological damage. In the present work, electron energy loss properties in liquid water and solid DNA were calculated based on the dielectric response theory for valence band electrons and atomic models for inner-shell electrons. For electron interactions with the valence band, an extended Drude dielectric function was fitted to experimental optical data and then checked by sum rules. The valance band was considered as composed of many subbands with different oscillator strength, binding energy and damping coefficient. The real and imaginary parts of the dielectric function and the energy loss function were all checked. For electron interactions with inner shells, the generalized oscillator strength was calculated using the sum-rule-constrained binary-encounter model and the local-plasma approximation. The differential inverse mean free paths for the valence band and inner shells were calculated using the Born approximation. Exchange effect was estimated using an approach based on the Moller cross-section. Results of the present work were compared with similar calculations by other authors. r 2007 Elsevier B.V. All rights reserved.