2882
J. Phys. Chem. A 2002, 106, 2882-2888
The Interaction of Methanol, Acetone, and Acetaldehyde with Ice and Nitric Acid-Doped Ice: Implications for Cirrus Clouds Paula K. Hudson, Mark A. Zondlo, and Margaret A. Tolbert* Department of Chemistry and Biochemistry and the CooperatiVe Institute for Research in EnVironmental Sciences, UniVersity of Colorado, Boulder 80309 ReceiVed: July 16, 2001; In Final Form: October 3, 2001
The uptake of methanol, acetone, and acetaldehyde by ice and nitric acid/ice surfaces representative of cirrus clouds has been measured using a Knudsen cell flow reactor equipped with FTIR spectroscopic observation of the condensed phase. Sticking coefficients and total equilibrium coverage for the organics on ice were obtained over the temperature range of 120-200 K. Both the sticking coefficients and coverage were found to decrease with increasing temperature for all three species. The coverage data was fit using a Langmuir adsorption model, and the results were extrapolated to typical cirrus cloud temperatures. By the use of estimates for the gaseous concentrations of the organic species, calculated coverages on ice at 210 K are extrapolated to be on the order of 1010 molecules/cm2 (10-4 ML) for methanol and acetone and
