Ambient observations of dimers from terpene oxidation in the gas phase: Implications for new particle formation and growth: Ambient Observations of Gas-Phase Dimers

• Published in: Geophysical research letters Vol. 44; no. 6
• Main Authors: Mohr, Claudia, Lopez-Hilfiker, Felipe D., Yli-Juuti, Taina, Heitto, Arto, Lutz, Anna, Hallquist, Mattias, D'Ambro, Emma L., Rissanen, Matti P., Hao, Liqing, Schobesberger, Siegfried, Kulmala, Markku, Mauldin, Roy L., Makkonen, Ulla, Sipilä, Mikko, Petäjä, Tuukka, Thornton, Joel A.
• Format: Journal Article
• Language: English
• Published: United States American Geophysical Union 28-03-2017
• Subjects: dimeric monoterpene oxidation dimers; GEOSCIENCES
• ISSN: 0094-8276

Here, we present ambient observations of dimeric monoterpene oxidation products (C16–20HyO6–9) in gas and particle phases in the boreal forest in Finland in spring 2013 and 2014, detected with a chemical ionization mass spectrometer with a filter inlet for gases and aerosols employing acetate and iodide as reagent ions. These are among the first online dual-phase observations of such dimers in the atmosphere. Estimated saturation concentrations of 10-15 to 10-6 µg m-3 (based on observed thermal desorptions and group-contribution methods) and measured gas-phase concentrations of 10-3 to 10-2 µg m-3 (~106–107 molecules cm-3) corroborate a gas-phase formation mechanism. Regular new particle formation (NPF) events allowed insights into the potential role dimers may play for atmospheric NPF and growth. The observationally constrained Model for Acid-Base chemistry in NAnoparticle Growth indicates a contribution of ~5% to early stage particle growth from the ~60 gaseous dimer compounds.