Final Technical Report

During the contract period, our experimental activities concentrated on ion-surface collision studies, gas phase collisions, the effects of adsorbates on field emission, and the origin of H3O+ in mass spectroscopy. In the area of ion-surface collisions we have measured sputtering yields for negative ions and electrons arising from collisions of ions and photons with a variety of metallic substrates upon which is known amount of adsorbate, which drastically alters the emission characteristics. Kinetic energy distributions of the ejected anions and electrons have also been determined. We have developed a theoretical model which, to a large degree, describes the process and elucidates the role of the adsorbate in the emission processes. In the category of gas-phase collisions, we reported work on proton transfer and ion-molecule reactions for reactants involving H3+ and D3+, measured absolute cross sections for a variety inelastic channels for reactants involving CH4+ and CF4, and measured electron detachment and decomposition cross sections for collisions of SF6- with N2. Additionally, we reported absolute cross sections for various reactive collisions involving collisional decomposition of SF6- and the reactants CF3+ and CHF3. The idea here was to use these measured cross sections to model and understand the salient features of the popular gaseous dielectric, SF6 , and the etching discharge which utilizes CHF3. A somewhat different set of experiments explored the role of adsorbates on the process of electron field emission and the nature and origin of the anomalous cation signal often seen at mass 19 amu in mass spectroscopy. The laboratory collision energies for these experiments ranged from a few electron volts up to 500 eV. The goal of all the studies was to develop an understanding of the collisional dynamics and pathways for systems which are both intellectually interesting and of some potential importance to various areas of applied physics