Date Awarded
1991
Document Type
Dissertation
Degree Name
Doctor of Philosophy (Ph.D.)
Department
Physics
Advisor
R L Champion
Abstract
Total cross sections for charge transfer and electron detachment for collisions of a variety of negative ions with atomic hydrogen have been separately determined for laboratory collision energies ranging from about 5 eV to 500 eV. The experiments are performed with an apparatus that utilizes a crossed-beam configuration with a radio-frequency discharge as the source of atomic hydrogen.;For collisions of H{dollar}\sp-{dollar}(D{dollar}\sp-{dollar}) with H the charge transfer cross sections increase monotonically with decreasing energy and display an isotope effect. at the lowest collision energies, the electron detachment cross sections are about one order of magnitude smaller than those for charge transfer; for the two projectiles the detachment cross sections are identical when compared at the same relative collision energy.;Total electron detachment cross sections have also been measured for collisions of Halogen anions with atomic hydrogen. For F{dollar}\sp-{dollar}, Cl{dollar}\sp-{dollar}, and Br{dollar}\sp-{dollar} projectiles the measured detachment cross sections increase with decreasing collision energy, and no energetic threshold is indicated; no charge transfer is observed. For I{dollar}\sp-{dollar} + H, however, the detachment cross sections are small at low collision energies, and increase rapidly with increasing energy. HI{dollar}\sp-{dollar} is known to form a stable molecular anion, and a small charge transfer cross section is measured to be less than 1 A{dollar}\sp2{dollar} at the highest collision energy.;For collisions of O{dollar}\sp-{dollar} and S{dollar}\sp-{dollar} with atomic hydrogen, electron detachment is also found to be the dominant electron loss mechanism, and the measured total detachment cross sections are found to increase with decreasing collision energy. For both projectiles, charge transfer cross sections are measured to be small and energetic thresholds are indicated.;The experimental results are compared with several calculations and previous measurements that overlap the present results at the highest energies, and are discussed, where possible, in terms of various intermolecular potentials which have been calculated previously.
DOI
https://dx.doi.org/doi:10.21220/s2-a95z-qm57
Rights
© The Author
Recommended Citation
Huels, Michael A., "Low-energy collisions of negative ions with atomic hydrogen" (1991). Dissertations, Theses, and Masters Projects. William & Mary. Paper 1539623798.
https://dx.doi.org/doi:10.21220/s2-a95z-qm57
