INVESTIGATION OF SURFACE ENERGY STATES OF SINGLE CRYSTAL METALS
Interim technical rept. 15 Jan 1962-15 Jan 1963
GENERAL MILLS INC MINNEAPOLIS MN
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A unique ion beam sputter cleaning apparatus has been developed to operate in a high vacuum sys tem. This apparatus, known as a unoplasmatron, creates positive ions from various gases and focuses them into a beam of controlled density and energy. Bombarding ion currents of 80 micro amps have been attained. Experiments have shown that this current is sufficient to produce large, smooth, brightly-etched surfaces on copper specimens in less than 1 hour. A contact poten tial device has also been developed to study the surface energy of single-crystal metals in a vacuum. This device utilizes the vibrating condenser technique. Contact potential measure ments of polycrystalline copper in this labora tory compare favorably with measurements reported in the literature. The changing contact poten tial of a clean titanium surface exposed to air has been measured. The contact potential varied from about 230 to 330 mhe accuracy of these measurements is believed to be about 5 mv.
- Electricity and Magnetism