| Title: | "Influence of humidity, temperature, and radicals on the formation and thermal properties of secondary organic aerosol (SOA) from ozonolysis of beta-pinene" |
| Author(s): | Emanuelsson EU; Watne AK; Lutz A; Ljungstrom E; Hallquist M; |
| Address: | "Atmospheric Science, Department of Chemistry and Molecular Biology, University of Gothenburg , SE-412 96 Gothenburg, Sweden" |
| ISSN/ISBN: | 1520-5215 (Electronic) 1089-5639 (Linking) |
| Abstract: | "The influence of water and radicals on SOAs produced by beta-pinene ozonolysis was investigated at 298 and 288 K using a laminar flow reactor. A volatility tandem differential mobility analyzer (VTDMA) was used to measure the evaporation of the SOA, enabling the parametrization of its volatility properties. The parameters extracted included the temperature at which 50% of the aerosol had evaporated (T(VFR0.5)) and the slope factor (S(VFR)). An increase in S(VFR) indicates a broader distribution of vapor pressures for the aerosol constituents. Reducing the reaction temperature increased S(VFR) and decreased T(VFR0.5) under humid conditions but had less effect on T(VFR0.5) under dry conditions. In general, higher water concentrations gave lower T(VFR0.5) values, more negative S(VFR) values, and a reduction in total SOA production. The radical conditions were changed by introducing OH scavengers to generate systems with and without OH radicals and with different [HO2]/[RO2] ratios. The presence of a scavenger and lower [HO2]/[RO2] ratio reduced SOA production. Observed changes in S(VFR) values could be linked to the more complex chemistry that occurs in the absence of a scavenger and indicated that additional HO2 chemistry gives products with a wider range of vapor pressures. Updates to existing ozonolysis mechanisms with routes that describe the observed responses to water and radical conditions for monoterpenes with endocyclic and exocyclic double bonds are discussed" |
| Keywords: | Aerosols Air Pollutants/*chemistry Bicyclic Monoterpenes Bridged Bicyclo Compounds/*chemistry Free Radical Scavengers/chemistry Humidity Hydroxyl Radical/antagonists & inhibitors/chemistry Monoterpenes/*chemistry Ozone/*chemistry Temperature Volatilizatio; |
| Notes: | "MedlineEmanuelsson, Eva U Watne, Agot K Lutz, Anna Ljungstrom, Evert Hallquist, Mattias eng Research Support, Non-U.S. Gov't 2013/09/05 J Phys Chem A. 2013 Oct 10; 117(40):10346-58. doi: 10.1021/jp4010218. Epub 2013 Sep 24" |
