Adsorption of oxygen and nitrogen on tantalum films. V

Journal Article · Fri Nov 30 23:00:00 EST 1973 · Z. Metallk., v. 64, no. 12, pp. 910-913

OSTI ID:4308159

Fromm, E; Duppel, H; Bauder, U

At 77 deg K the sticking probability for nitrogen on gas-free films has a constant value of 1, and at a coverage of approximately 7 x 10/sup 14/ molecules/cm/sup 2/ it falls rapidly some 5 to 6 orders of magnitude. The electrical resistance is hardly affected by the adsorption process. Heating the film to 300 deg K leads to a very rapid increase in pressure. Exposing the film again to nitrogen at 77 deg K shows that the coverage at which the sticking probability falls is now considerably smaller. Repeated heating to 300 deg K does not further change in the reaction. From measurements of the increase in pressure it can be concluded that the first nitrogen exposure results in a rapid chemisorption. Afterwards, nitrogen molecules are reversibly physisorbed on the chemisorbed layer. Additional nitrogen-exposure of the same film results only in physisorption. The maximum amount of physisorbed nitrogen is approximately 3.5 x 10/sup 14/ molecules/cm/sup 2/. (GE)

• Research Organization: Max-Planck-Institut fuer Metallforschung, Stuttgart
• NSA Number: NSA-29-027322
• OSTI ID: 4308159
• Journal Information: Z. Metallk., v. 64, no. 12, pp. 910-913, Journal Name: Z. Metallk., v. 64, no. 12, pp. 910-913; ISSN ZEMTA
• Country of Publication: Germany
• Language: German

Related Subjects

*NITROGEN-- CHEMISORPTION
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LOW TEMPERATURE
MEDIUM TEMPERATURE
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N50330 --Metals
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