Calculations of electron inelastic mean free paths. V. Data for 14 organic compounds over the 50–2000 eV range

TLDR

The discrepancies arise from extrapolating the TPP‑2 formula, developed for high‑density elements, to low‑density organic materials. This study reports electron inelastic mean free path calculations for 50–2000 eV electrons in 14 organic compounds. The authors analyzed IMFP data for elements and organics together and derived a modified empirical expression for a parameter in the predictive IMFP equation. The calculated IMFPs for the 14 organic compounds exhibit greater similarity in magnitude and energy dependence than in previous element‑based studies, differ from the TPP‑2 predictions by about 40 %, and are well described by the newly derived TPP‑2M empirical equation.

Abstract

Abstract We report calculations of electron inelastic mean free paths (IMFPs) of 50–2000 eV electrons for a group of 14 organic compounds: 26‐ n ‐paraffin, adenine, β‐carotene, bovine plasma albumin, deoxyribonucleic acid, diphenylhexatriene, guanine, kapton, polyacetylene, poly(butene‐1‐sulfone), polyethylene, polymethylmethacrylate, polystyrene and poly(2‐vinylpyridine). The computed IMFPs for these compounds showed greater similarities in magnitude and in the dependences on electron energy than was found in our previous calculations for groups of elements and inorganic compounds (Papers II and III in this series). Comparison of the IMFPs for the organic compounds with values obtained from our predictive IMFP formula TPP‐2 showed systematic differences of ∼40%. These differences are due to the extrapolation of TPP‐2 from the regime of mainly high‐density elements (from which it had been developed and tested) to the low‐density materials such as the organic compounds. We analyzed the IMFP data for the groups of elements and organic compounds together and derived a modified empirical expression for one of the parameters in our predictive IMFP equation. The modified equation, denoted TPP‐2M, is believed to be satisfactory for estimating IMFPs in elements, inorganic compounds and organic compounds.