PHYS 633 |
| Organic molecules at the surface of sulfuric acid aerosols may alter the rates of heterogeneous reactions in the atmosphere. The packing of these surfactants can be determined from surface tension measurements. In particular, the soluble alcohols butanol, hexanol and octanol reach 44%, 56%, and 68% of full monolayer coverage at 296 K in 60 wt% H2SO4. The alcohols pack ~8% more tightly at 250 K than at 296 K. Hexanoic acid packs ~10% more tightly than hexanol, while hexylamine reaches only ~60% of the coverage of hexanol. Molecular beam scattering experiments test the efficacy of hexanol to block the entry of HCl into surfactant-coated sulfuric acid. When the hexanol packing is ~2/3 or less of a monolayer, HCl entry is enhanced by hexanol, but when the packing exceeds this value, entry is impeded. Therefore, hexanol films can augment or hinder the entry of HCl depending on surface coverage. |
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PHYS Poster Session - Physical Chemistry of Atmospheric Processes
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster
Sci-Mix
Division of Physical Chemistry |