Resonant Charge Exchange Studies with Hyperthermal Energy Ion Beams: Development of Multi-Detection Capabilities and a Data Acquisition System

摘要

The overall research program described in this report is to investigate the interactions of hyperthermal (10-100 eV) and keV ions with clean and adsorbate-covered metal surfaces. Particular emphasis is placed on the study of ion-surface charge exchange processes. Progress in instrumentation includes: completion of the general apparatus, the successful production of low phase-space alkali and noble gas beams ranging in energy from about 10 eV to several keV, completion of two hemispherical analyzers for detecting scattered ions (one with high-resolution capabilities, the other for large angle scattering studies), design details of the position-sensitive pulse-counting detectors for multi-energy detection, and the configuration of a Macintosh II-based data acquisition system. Scientific progress includes: measurements of 50 eV to 4keV alkali scattering from clean and cesiated Cu(110), simulations using Hartree-Fock pair potentials that give good agreement with the 100 to 400 eV Na(+) scattering from Cu(110), trajectory analysis to identify peaks in the Na(+) energy spectra, measurements of charge transfer probabilities for alkalis scattered from (Cu(110)) with low coverages (<1/10 monolayer) of Cs adsorbates, and ongoing development of a model that includes both local and collective effects of the Cs overlayers in determining charge transfer probabilities. Keywords: Hyperthermal Energy Ion Beams; Resonant Charge Exchange; Ion Scattering Instrumentation; Multi-Channel Electrostatic Detectors. (jhd)