Electron mean-free pathlengths through monolayers of cadmium arachidate

Abstract

The inelastic mean-free pathlengths λ, of 1042–1402 eV electrons through cadmium arachidate (C19H39COO)2Cd, monolayers have been determined from attenuation measurements of the core level photoemission (XPS) signals from gold, silver and indium substrates. Both fixed angle-variable overlayer thickness experiments and variable angle-fixed overlayer thickness experiments were performed. We derive a preferred value of 3.6 nm at 1117 eV and an E0.5 energy dependence over the narrow energy range considered. Values determined for bulk cadmium arachidate and arachidic acid from absolute intensity comparisons with gold and silver are close to the monolayer values. The results are discussed in the light of the controversy existing concerning other values of λ’s determined for organic and polymeric materials.