Electron inelastic mean free paths in a group of bioorganic compounds and liquid water over the energy range of 20–20,000 eV

Abstract

We have carried out the systematic calculations of inelastic mean free paths (IMFPs) of energetic electrons in seven bioorganic compounds (Adenine, Guanine, Thymine, Cytosine, Uracil, DNA, and Protein) and liquid water in the energy range from 20 eV to 20 keV. The calculations are based on our previous optical-data model with the Born–Ochkur exchange correction, but a combinational second-order perturbation correction is introduced into this model and the energy gap is accounted for in the present work. The introduced second-order perturbation correction includes the two parts, one is the correction due to the Barkas effect and the other is called the pseudo-Coulomb-field correction proposed heuristically. The two corrections are implemented respectively in the range above and below a characteristic energy. We have compared our calculated IMFPs for the considered compounds with other theoretical evaluations of IMFP. The comparisons reveal the significant effects of the introduced second-order correction on the IMFP calculations at energies below 200 eV and meanwhile show good agreement between all the theoretically evaluated IMFPs above about 300 eV. The presented calculation data provide the useful and alternative IMFPs for the bioorganic compounds under consideration and liquid water in the study of radiation biological effects.