Biomaterial Database

Particle phase acidity and oligomer formation in secondary organic aerosol. 2004

Song Gao, and Nga L Ng, and Melita Keywood, and Varuntida Varutbangkul, and Roya Bahreini, and Athanasios Nenes, and Jiwen He, and Kee Y Yoo, and J L Beauchamp, and Robert P Hodyss, and Richard C Flagan, and John H Seinfeld

Department of Environmental Science, California Institute of Technology, MC 210-41, Pasadena, California 91125, USA.

A series of controlled laboratory experiments are carried out in dual Teflon chambers to examine the presence of oligomers in secondary organic aerosols (SOA) from hydrocarbon ozonolysis as well as to explore the effect of particle phase acidity on SOA formation. In all seven hydrocarbon systems studied (i.e., alpha-pinene, cyclohexene, 1-methyl cyclopentene, cycloheptene, 1-methyl cyclohexene, cyclooctene, and terpinolene), oligomers with MW from 250 to 1600 are present in the SOA formed, both in the absence and presence of seed particles and regardless of the seed particle acidity. These oligomers are comparable to, and in some cases, exceed the low molecular weight species (MW < 250) in ion intensities in the ion trap mass spectra, suggesting they may comprise a substantial fraction of the total aerosol mass. It is possible that oligomers are widely present in atmospheric organic aerosols, formed through acid- or base-catalyzed heterogeneous reactions. In addition, as the seed particle acidity increases, larger oligomers are formed more abundantly in the SOA; consequently, the overall SOA yield also increases. This explicit effect of particle phase acidity on the composition and yield of SOA may have important climatic consequences and need to be considered in relevant models.

UI	MeSH Term	Description	Entries
D010083	Oxidants, Photochemical	Compounds that accept electrons in an oxidation-reduction reaction. The reaction is induced by or accelerated by exposure to electromagnetic radiation in the spectrum of visible or ultraviolet light.	Photochemical Oxidants
D010126	Ozone	The unstable triatomic form of oxygen, O3. It is a powerful oxidant that is produced for various chemical and industrial uses. Its production is also catalyzed in the ATMOSPHERE by ULTRAVIOLET RAY irradiation of oxygen or other ozone precursors such as VOLATILE ORGANIC COMPOUNDS and NITROGEN OXIDES. About 90% of the ozone in the atmosphere exists in the stratosphere (STRATOSPHERIC OZONE).	Ground Level Ozone,Low Level Ozone,Tropospheric Ozone,Level Ozone, Ground,Level Ozone, Low,Ozone, Ground Level,Ozone, Low Level,Ozone, Tropospheric
D010316	Particle Size	Relating to the size of solids.	Particle Sizes,Size, Particle,Sizes, Particle
D006838	Hydrocarbons	Organic compounds that primarily contain carbon and hydrogen atoms with the carbon atoms forming a linear or circular structure.	Hydrocarbon,Saturated Hydrocarbons,Unsaturated Hydrocarbons,Hydrocarbons, Saturated,Hydrocarbons, Unsaturated
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000336	Aerosols	Colloids with a gaseous dispersing phase and either liquid (fog) or solid (smoke) dispersed phase; used in fumigation or in inhalation therapy; may contain propellant agents.	Aerosol
D000393	Air Pollutants	Any substance in the air which could, if present in high enough concentration, harm humans, animals, vegetation or materials. Substances include GASES; PARTICULATE MATTER; and volatile ORGANIC CHEMICALS.	Air Pollutant,Air Pollutants, Environmental,Environmental Air Pollutants,Environmental Pollutants, Air,Air Environmental Pollutants,Pollutant, Air,Pollutants, Air,Pollutants, Air Environmental,Pollutants, Environmental Air