Dependence of particle nucleation and growth on high-molecular-weight gas-phase products during ozonolysis of α-pinene 1Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota, 55455, USA
08 Aug 2013
2Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, Colorado, 80307, USA
3Department of Applied Physics, University of Eastern Finland, Kuopio 70211, Finland
Received: 08 March 2013 – Published in Atmos. Chem. Phys. Discuss.: 08 April 2013 Abstract. We report the first time-dependent measurements of high-molecular-weight (up
to 700 amu) gas-phase oxidation products from α-pinene ozonolysis in
an aerosol chamber under dry and low-NOx conditions. Measurements of
products having mole fractions ranging from 10−14 to 10−11 were
carried out with a chemical ionization mass spectrometer (the Cluster CIMS).
Most products that were correlated with number concentrations of the
smallest particles measured (10–20 nm) had molecular weights in the 430–560 amu range. Those products are proposed to be likely responsible for the
initial nuclei formation and the early growth of the freshly nucleated
particles based on their high molecular weights and chemical identities,
both of which suggest low-volatility compounds. Another group of oxidation
products in the lower mass range of 140–380 amu was well correlated with
particles larger than 20 nm. We postulate that those products contributed to
the later growth of particles (i.e., larger than 20 nm in diameter).
Although particle nucleation in this study was primarily due to condensation
of oxidation products from α-pinene ozonolysis, the involvement of
residual sulfuric acid vapor in particle nucleation cannot be totally
Revised: 23 June 2013 – Accepted: 05 July 2013 – Published: 08 August 2013
Citation: Zhao, J., Ortega, J., Chen, M., McMurry, P. H., and Smith, J. N.: Dependence of particle nucleation and growth on high-molecular-weight gas-phase products during ozonolysis of α-pinene, Atmos. Chem. Phys., 13, 7631-7644, doi:10.5194/acp-13-7631-2013, 2013.