Chemistry and Physics Faculty Articles

Document Type

Article

Publication Date

11-16-2001

Publication Title

Journal of Geophysical Research: Atmospheres

Keywords

Constituent sources and sinks, Troposphere

ISSN

2169-897X

Volume

106

Issue/No.

D21

First Page

27603

Last Page

27618

Abstract

Observations of particle nucleation and growth during ozonolysis of α-pinene were carried out in Calspan's 600 m3 environmental chamber utilizing relatively low concentrations of α-pinene (15 ppb) and ozone (100 ppb). Model simulations with a comprehensive sectional aerosol model which incorporated the relevant gas-phase chemistry show that the observed evolution of the size distribution could be simulated within the accuracy of the experiment by assuming only one condensable product produced with a molar yield of 5% to 6% and a saturation vapor pressure (SVP) of about 0.01 ppb or less. While only one component was required to simulate the data, more than one product may have been involved, in which case the one component must be viewed as a surrogate having an effective SVP of 0.01 ppb or less. Adding trace amounts of SO2greatly increased the nucleation rate while having negligible effect on the overall aerosol yield. We are unable to explain the observed nucleation in the α-pinene/ozone system in terms of classical nucleation theory. The nucleation rate and, more importantly, the slope of the nucleation rate versus the vapor pressure of the nucleating species would suggest that the nucleation rate in the α-pinene/ozone system may be limited by the initial nucleation steps (i.e., dimer, trimer, or adduct formation).

Comments

©2001 by the American Geophysical Union

DOI

10.1029/2001JD900018

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