Interfacial chemistry in aqueous nanodroplet encounters with a reactive gas

ENVR 3

Chad D. Vecitis, vecitis@caltech.edu, Shinichi Enami, Michael R. Hoffmann, mrh@caltech.edu, and A. J. Colussi, ajcoluss@caltech.edu. Environmental Science and Engineering, California Institute of Technology, W. M. Keck Laboratories 138-78, 1200 E. California Blvd., Pasadena, CA 91125
Anions ejected from the surface of aqueous I-, SO32- or S2O32- solution nanodroplets exposed to dilute O3 atmospheres are directly monitored by mass spectrometry. I- oxidation yields iodate and triiodide in amounts that exceed net interfacial I- losses, revealing that I- from the droplet core replenishes the probed layers. SO32- and S2O32- oxidations lead to bisulfate and dithionate, respectively. Inert surfactant additions markedly depress interfacial loss rates R(Xn-), except for I-, and further magnify apparent product yields. Neither R(Xn-)s correlate with second-order rate constants kII(Xn- + O3)s in bulk solution, nor do R(Xn-) vs. [O3(g)] dependences adhere to macroscopic models of gas-liquid reactions, disproving prevailing notions about reactive events between atmospheric gases and fine aerosol droplets.
 

Atmospheric Aerosol Processes
8:30 AM-11:45 AM, Sunday, August 19, 2007 Boston Park Plaza -- Stanbro Rm, Oral

Division of Environmental Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007