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Proceedings Paper

Ultrahigh vacuum studies of the surfaces of ice and sulfuric acid
Author(s): Jeffrey T. Roberts
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Paper Abstract

The surface chemical properties of ice and sulfuric acid in ultrahigh vacuum have been studied using temperature programmed desorption and Fourier transform infrared reflection absorption spectroscopy (FTIRAS). Ice and sulfuric acid were deposited on Pt(111) and W(100) as films between 10 and 100 monolayers thick. FTIRAS measurements imply that amorphous ice has a greater density of `dangling,' surface OH groups than crystalline ice. The crystalline and amorphous surfaces are also chemically different: adsorbate capable of forming hydrogen bonds of the type X(DOT)(DOT)(DOT)H-O exhibit a desorption state that is unique to amorphous ice. The adsorption of OCIO on ice was investigated in order to estimate the coverage of adsorbed OCIO on stratospheric ice particles. The sticking coefficient at 100 K is nearly unity. At low coverages, desorption is first order, with an activation energy of 23 +/- 1 kJ(DOT)mol-1 and a frequency factor of 1.5 X 109+/- 1 s-1. The coverage of OCIO on stratospheric ice particles is probably so low that thermal- and photochemistry are unimportant in the atmosphere. For H2SO4, the dangling OH group cannot be spectroscopically observed, nor does HCl adsorb or absorb at 100 K.

Paper Details

Date Published: 25 September 1995
PDF: 10 pages
Proc. SPIE 2547, Laser Techniques for Surface Science II, (25 September 1995); doi: 10.1117/12.221469
Show Author Affiliations
Jeffrey T. Roberts, Univ. of Minnesota (United States)

Published in SPIE Proceedings Vol. 2547:
Laser Techniques for Surface Science II
Janice M. Hicks; Wilson Ho; Hai-Lung Dai, Editor(s)

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