HR: 0830h
AN: A51F-0745    [PDF]
TI: Methanol Reaction With Sulfuric Acid: Implications for Organo-Sulfate Aerosol Chemistry in the Middle and Upper Troposphere
AU: * Van Loon, L L
EM: lvanloon@chemistry.ohio-state.edu
AF: The Ohio State University, Dept of Chemistry 100 W 18th Ave, Columbus, OH 43210-1106 United States
AU: Allen, H C
EM: allen@chemistry.ohio-state.edu
AF: The Ohio State University, Dept of Chemistry 100 W 18th Ave, Columbus, OH 43210-1106 United States
AB: Current estimates of global atmospheric methanol predict higher concentrations than those observed in the middle and upper troposphere over the Atlantic and Pacific oceans suggesting that an unknown sink for methanol exists. One possible explanation is the uptake of methanol by sulfate aerosols. The esterification of methanol by sulfuric acid has been studied since the 1950's, yet there is no complete quantitative or molecular level understanding of the reaction system. Using vibrational broad bandwidth sum frequency generation (BBSFG) the surface structure of methanol-sulfuric acid (SA) solutions using atmospherically relevant SA concentrations was examined. Liquid studies using Raman spectroscopy confirm protonation of methanol and formation of methyl hydrogen sulfate. The presence of water controls the formation of dimethyl sulfate. Surface studies reveal the formation of methyl hydrogen sulfate versus dimethyl sulfate from differing solvation effects at the surface relative to the bulk. These results further elucidate the molecular level picture of methanol-sulfuric acid aerosols and their role in middle and upper tropospheric chemistry.
DE: 0345 Pollution--urban and regional (0305)
DE: 4801 Aerosols (0305)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting