Elastic scattering of electrons from dimethylsulfide and dimethylsulfoxide

Abstract

Differential cross sections for elastic scattering of electrons from dimethylsulfide and dimethylsulfoxide in the energy range from 30 to 500 eV are presented. The cross sections have been measured using a crossed-beam-type high-resolution electron spectrometer. The measured cross sections have been put on an absolute scale using the relative flow technique. The measured differential cross sections show an increase in the midangles at 30 and 50 eV for both the molecules that is characteristic of resonant enhanced $d$-wave scattering. Total and momentum-transfer cross sections were derived by integrating over all angles after extrapolating the data to forward and backward angles using a least-squares fitting procedure based on the Legendre polynomial expansion. Independent-atom-model-based theoretical calculations incorporating static, exchange, and polarization potentials are also reported and compared with the experimental cross sections. For energies lower than 100 eV, it is seen that the independent-atom-model calculations fail to predict the qualitative behavior of the differential cross sections correctly, while at energies greater than 100 eV it seems to describe the data adequately. The effect of polarization and enhancement of cross sections through $d$-wave scattering at low energies is also analyzed.