The PI plans to address the fundamental physical processes that affect the behavior of semi-volatile organic compounds (SOCS) in the troposphere. Methods will be developed to collect particle samples suitable for surface area analysis. Specific surface areas of urban and, for the first time, rural aerosols will be determined. The results will be used to assess whether 10 urban and rural particles differ significantly in specific surface area; 2) published estimates of specific surface area are reasonable; and 3) the current use of estimated surface areas in deposition modeling is appropriate. Concentrations of n-alkanes and polycyclic aromatic hydrocarbons will also be measured to investigate, in a preliminary fashion, the effect of particle surface area on the phase distribution of SOC's
