Real-Time, Single-Particle Measurements of Oligomers in Aged Ambient Aerosol Particles

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• 作者：Kerri A. Denkenberger ; Ryan C. Moffet ; John C. Holecek ; Thomas P. Rebotier ; Kimberly A. Prather
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：August 1, 2007
• 年：2007
• 卷：41
• 期：15
• 页码：5439 - 5446
• 全文大小：395K
• 年卷期：v.41,no.15(August 1, 2007)
• ISSN：1520-5851

文摘

Unique high mass negative ions in the -200 to -400mass/charge range with repetitive spacings of 12, 14, and16 units, representative of oligomeric species, havebeen detected in single ambient submicrometer aerosolparticles using real-time single-particle mass spectrometryduring the Study of Organic Aerosols field campaignconducted in Riverside, CA (SOAR) in August and November2005. These oligomer-containing particles represented 33-40% of the total detected particles and contained otherindicators of aging including oxidized organic carbon, amine,nitrate, and sulfate ion markers. Overall, the highestmass oligomeric patterns were observed in small acidic 140-200 nm particles in the summer. Also during the summer,increased oligomer intensities were observed when theparticles were heated with a thermodenuder. We hypothesizethat heat removed semivolatile species, thereby increasingparticle acidity, while concentrating the oligomericprecursors and accelerating oligomer formation. Differencesin oligomer behavior with respect to particle size andheating can be attributed to seasonal differences inphotochemical oxidation, the relative amount of ammonium,and particle acidity.