Atmos. Chem. Phys. Discuss., 10, 27673-27693, 2010
© Author(s) 2010. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
The effect of trimethylamine on atmospheric nucleation involving H2SO4
M. E. Erupe1, A. A. Viggiano2, and S.-H. Lee1
1Kent State University, Department of Chemistry and Biochemistry, Kent, Ohio 44240, USA
2Air Force Research Laboratory, Hanscom Air Force Base, Massachusetts, USA

Abstract. Field observations and quantum chemical calculations have shown that organic amine compounds may be important in new particle formation processes involving H2SO4. Here, we report laboratory observations that investigate the effect of trimethylamine (TMA) on H2SO4-H2O nucleation made under aerosol precursor concentrations typically found in the lower troposphere ([H2SO4] of 106–107 cm−3; [TMA] of 180–1350 pptv). These results show that the threshold [H2SO4] needed to produce the unity nucleation rate ([H2SO4] of 106–107 cm−3) and the number of precursor molecules in the critical cluster (nH2SO4 = 4–6; nTMA = 1) are surprisingly similar to those found in the ammonia (NH3) ternary nucleation study (Benson et al., 2010a). At lower RH, however, enhancement in nucleation rates due to TMA was up to an order of magnitude greater than that due to NH3. These findings imply that both amines and NH3 are important nucleation species, but under dry atmospheric conditions, amines may have stronger effects on H2SO4 nucleation than NH3. Aerosol models should therefore take into account inorganic and organic bases together to fully understand the widespread new particle formation events in the lower troposphere.

Citation: Erupe, M. E., Viggiano, A. A., and Lee, S.-H.: The effect of trimethylamine on atmospheric nucleation involving H2SO4, Atmos. Chem. Phys. Discuss., 10, 27673-27693, doi:10.5194/acpd-10-27673-2010, 2010.
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