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Proceedings Paper

Removal of adsorbed gases with CO2 snow
Author(s): Richard R. Zito
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Paper Abstract

During the outgassing of orbiting astronomical observatories, the condensation of molecular species on optical surfaces can create difficulties for astronomers. The problem is particularly severe in ultraviolet astronomy where the adsorption of only a few atomic layers of some substances can be very damaging. In this paper the removal of adsorbed atomic layers using carbon dioxide snow is discussed. The rate of removal of adsorbed layers of isopropyl alcohol, Freon TF, and deionized distilled water on Teflon substrates was experimentally determined. The removal of fingerprints (containing fatty acids such as stearic acid) from optical surfaces is also demonstrated. The presence and rate of removal of the multilayers was monitored by detecting the molecular dipole field of adsorbed molecular species. For isopropyl alcohol, Freon TF (trichlorotrifluoroethane), and water adsorbed multilayers were removed in under 1.5 seconds. Fingerprint removal was much more difficult and required 20 seconds of spraying with a mixture of carbon dioxide snow flakes and atomized microdroplets of isopropyl alcohol.

Paper Details

Date Published: 1 September 1991
PDF: 7 pages
Proc. SPIE 1494, Space Astronomical Telescopes and Instruments, (1 September 1991); doi: 10.1117/12.46742
Show Author Affiliations
Richard R. Zito, Richard R. Zito R & D Corp. (United States)

Published in SPIE Proceedings Vol. 1494:
Space Astronomical Telescopes and Instruments
Pierre Y. Bely; James B. Breckinridge, Editor(s)

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