Continuum Multiple Scattering Xα Calculations of Elastic Cross Sections in Electron-Molecule Scattering

Abstract

In recent years several research groups have initiated experimental programs using electron transmission spectroscopy (ETS) to grobe the existence of low lying negative ion states in polyatomic molecules.1–8 Since in many cases more than one negative ion state is revealed by the observation of multiple resonances in the ETS experiment7,8, any acceptable theoretical model for the interpretation of these results must be free of any parameterization which is dependent on a prior knowledge of the nature of the resonances. Techniques, which depend on parameter adjustment until the first calculated resonance is in agreement with the experimentally observed one, are of little predictive value for molecules such as the chloroethylenes which contain multiple resonances.? At the present time two models which avoid this dilemma are available.9–14 The first one, which is primarily a one center model, is the method recently developed by Jain and Thompson (JT).9,10 It has proved successful in providing a detailed interpretation of electron scattering results for methane, water, and ammonia and is discussed elsewhere in this volume. The second model is the continuum multiple scattering Χα (MSXα) method originally proposed by Dehmer and Dill11,but which we have modified so that it is a practical non-empirical method capable of producing total elastic cross sections and differential cross sections for polyatomic molecules containing up to twenty atoms and for electron impact energies from 0 to 100 eV.12–14 KeywordsDifferential Cross SectionPolyatomic MoleculeIntegral Cross SectionElastic Cross SectionMultiple ResonanceThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.