Electron Detachment in Low-Energy Collisions of H- and D- with He

Measurements and calculations have been made of elastic scattering and electron detachment in collisions of H− and D− with He at energies of 5-120 eV. The measurements show no other inelastic processes occurring in this energy range. The mechanism responsible for electron detachment is assumed to be the crossing of the H− bound state with the continuum of free states; the bound state is then assigned a complex energy. The measured elastic scattering differential cross section shows no structure except at Eθ∼200 eV deg, where there is a region of downward curvature in the graph of logσ vs θ. This is interpreted as the threshold angle for electron detachment, and it is directly related to the crossing point. By empirically fitting the experimental differential cross section, the general features of the complex potential were obtained. By using the resulting potentials, the total detachment cross section was calculated and compared to the experimental results of Bailey, May, and Muschlitz. Only fair agreement is found at low energies, and poor agreement at higher energies (\u3e100 eV). The theory predicts an isotope effect in the elastic differential cross section, and this effect provides a test of the theory. A careful series of experiments at 20 eV displayed the effect. A preliminary measurement of the electron energy spectrum was also made

Fundamental processes in low energy collisions of alkali anions and atoms

Negative ion sources often employ alkali metal atoms in one way or another in order to increase their yield. Models which describe equilibrium conditions or the nature of energy transport within these sources require, among other things, information about the two-body cross sections for various scattering channels which involve either alkali negative ions or alkali atoms. The purpose of this report is to provide a brief summary of recent experimental observations in which collisions of alkali anions (M/sup -/) with various atoms and molecules and collisions of H/sup -/ and D/sup -/ with alkali atoms (M) have been investigated. The energy range of the experiments, 5 < E < 500 eV, includes those kinetics energies often found in discharge-type ion sources. The specific experiments which will be discussed focus upon measurements of total cross sections for collisional electron detachment and charge transfer of negative ions. 16 refs., 7 figs

Negative ion detachment cross sections. Interim progress report

The authors have measured absolute cross sections for electron detachment and charge exchange for collision of O and S with atomic hydrogen, have investigated the sputtering and photodesorption of negative ions from gas covered surfaces, and have begun an investigation of photon-induced field emission of electrons from exotic structures. Brief descriptions of these activities as well as future plans for these projects are given below

Negative ion detachment cross sections. Interim progress report

During past year, we have measured cross sections for associative and collisional detachment for several negative ions in collisions with atomic hydrogen. Additional experiments have been performed in which the formation of secondary negative ions and electrons by means of low energy ion impact on surfaces has been studied. Brief descriptions of these activities along with future plans for the project follow

Collisions of alkali negative ions with atomic and molecular targets

Ion-beam measurements are presented for the total cross section sigma/sub e/(E) for electron detachment of Na/sup -/, K/sup -/. and Cs/sup -/ in low-energy (E/sub lab/ < 300 eV) collisions with atomic and molecular targets. The data for the Cs/sup -/ projectile is previously unreported and extends our recent study of Na/sup -/ and K/sup -/. The motivation for this work is due in part to the observation that these alkali-metal anions (denoted M/sup -/) are similar to H/sup -/ in that they have two s-electrons outside a closed shell. In particular, it is of interest to determine whether the energy dependence of sigma/sub e/(E) for M/sup -/ is similar to that observed for H/sup -/. 21 refs., 5 figs

Comparison of different methods of determining the sex type of an occupation

The \u27sex type\u27 of an occupation is frequently used as an independent variable in vocational, organizational, and sex-role research. The sex type of an occupation interacts with the sex of subjects and applicants and affects a host of dependent variables including choice and interest in an occupation, selection of decisions, perceived success, and expectations regarding performance. Recently, the sex type of an occupation has also come to play an integral role in comparable worth theory, where it is argued that female sex-typed occupations are paid less than they are worth. The sex type of an occupation has been frequently investigated. Two major methods, actual rates of participation in the labor market and subjective estimates, have been used to determine the sex type of an occupation. The present study demonstrated that these two methods of estimating sex type may lead to different results