title: Optical Properties of Secondary Organic Aerosol from cis-3-Hexenol and cis-3-Hexenyl Acetate: Effect of Chemical Composition, Humidity, and Phase.
abstract: Atmospheric aerosols play an important role in Earth's radiative balance directly, by scattering and absorbing radiation, and indirectly, by acting as cloud condensation nuclei (CCN). Atmospheric aerosol is dominated by secondary organic aerosol (SOA) formed by the oxidation of biogenic volatile organic compounds (BVOCs). Green leaf volatiles (GLVs) are a class of BVOCs that contribute to SOA, yet their role in the Earth's radiative budget is poorly understood. In this work we measured the scattering efficiency (at 450, 525, and 635 nm), absorption efficiency (between 190 and 900 nm), particle phase, bulk chemical properties (O:C, H:C), and molecular-level composition of SOA formed from the ozonolysis of two GLVs: cis-3-hexenol (HXL) and cis-3-hexenyl acetate (CHA). Both HXL and CHA produced SOA that was weakly absorbing, yet CHA-SOA was a more efficient absorber than HXL-SOA. The scatter efficiency of SOA from both systems was wavelength-dependent, with the stronger dependence exhibited by HXL-SOA, likely due to differences in particle size. HXL-SOA formed under both dry (10% RH) and wet (70% RH) conditions had the same bulk chemical properties (O:C), yet significantly different optical properties, which was attributed to differences in molecular-level composition. We have found that SOA derived from green leaf volatiles has the potential to affect the Earth's radiative budget, and also that bulk chemical properties can be insufficient to predict SOA optical properties.
authors.affiliation: Department of Chemistry, University of Vermont , Burlington, Vermont 05405, United States.
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Harvey
authors.affiliation: School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Bateman
authors.affiliation: Department of Chemistry, University of Vermont , Burlington, Vermont 05405, United States.
authors.forename: Shashank
authors.initials: S
authors.lastname: Jain
authors.affiliation: School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Yong Jie
authors.initials: YJ
authors.lastname: Li
authors.affiliation: School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.|Department of Earth and Planetary Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Scot
authors.initials: S
authors.lastname: Martin
authors.affiliation: Department of Chemistry, University of Vermont , Burlington, Vermont 05405, United States.
authors.forename: Giuseppe A
authors.initials: GA
authors.lastname: Petrucci
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D006813:Humidity; D010084:Oxidation-Reduction; D010316:Particle Size; D055549:Volatile Organic Compounds / Q000737:chemistry
chemical_list: D000336:Aerosols; D055549:Volatile Organic Compounds