Characteristic Energy Loss Spectra and Optical Constants of Some Solid Hydrocarbons

Abstract

Characteristic electron energy loss measurements on some solid hydrocarbons, β-carotene, diphenyl-polyenes and paraffins applying 40 keV electrons are reported. From the energy loss function −Im [1⁄ε(ΔE)] the dielectric constant ε(ΔE) is calculated by means of a Kramers-Kronig transformation. It is possible to divide the optical properties of these compounds into three spectral regions. The low-lying losses below 8 eV observed in β-carotene and diphenyl-polyenes are interpreted by the single excitation of π-electrons. In the range 8 to 16 eV the excitations of σ-electrons are observed. The electron loss at 21 eV is due to the plasma oscillations of π- and σ-electrons.