TY - JOUR
T1 - Transitions from functionalization to fragmentation reactions of laboratory Secondary Organic Aerosol (SOA) generated from the OH oxidation of alkane precursors
AU - Lambe, Andrew T.
AU - Onasch, Timothy B.
AU - Croasdale, David R.
AU - Wright, Justin P.
AU - Martin, Alexander T.
AU - Franklin, Jonathan P.
AU - Massoli, Paola
AU - Kroll, Jesse H.
AU - Canagaratna, Manjula R.
AU - Brune, William H.
AU - Worsnop, Douglas R.
AU - Davidovits, Paul
PY - 2012/5/15
Y1 - 2012/5/15
N2 - Functionalization (oxygen addition) and fragmentation (carbon loss) reactions governing secondary organic aerosol (SOA) formation from the OH oxidation of alkane precursors were studied in a flow reactor in the absence of NOx. SOA precursors were n-decane (n-C10), n-pentadecane (n-C15), n-heptadecane (n-C17), tricyclo[5.2.1.0 2,6]decane (JP-10), and vapors of diesel fuel and Southern Louisiana crude oil. Aerosol mass spectra were measured with a high-resolution time-of-flight aerosol mass spectrometer, from which normalized SOA yields, hydrogen-to-carbon (H/C) and oxygen-to-carbon (O/C) ratios, and C xHy+, CxHyO+, and C xHyO2+ ion abundances were extracted as a function of OH exposure. Normalized SOA yield curves exhibited an increase followed by a decrease as a function of OH exposure, with maximum yields at O/C ratios ranging from 0.29 to 0.74. The decrease in SOA yield correlates with an increase in oxygen content and decrease in carbon content, consistent with transitions from functionalization to fragmentation. For a subset of alkane precursors (n-C10, n-C15, and JP-10), maximum SOA yields were estimated to be 0.39, 0.69, and 1.1. In addition, maximum SOA yields correspond with a maximum in the CxHyO+ relative abundance. Measured correlations between OH exposure, O/C ratio, and H/C ratio may enable identification of alkane precursor contributions to ambient SOA.
AB - Functionalization (oxygen addition) and fragmentation (carbon loss) reactions governing secondary organic aerosol (SOA) formation from the OH oxidation of alkane precursors were studied in a flow reactor in the absence of NOx. SOA precursors were n-decane (n-C10), n-pentadecane (n-C15), n-heptadecane (n-C17), tricyclo[5.2.1.0 2,6]decane (JP-10), and vapors of diesel fuel and Southern Louisiana crude oil. Aerosol mass spectra were measured with a high-resolution time-of-flight aerosol mass spectrometer, from which normalized SOA yields, hydrogen-to-carbon (H/C) and oxygen-to-carbon (O/C) ratios, and C xHy+, CxHyO+, and C xHyO2+ ion abundances were extracted as a function of OH exposure. Normalized SOA yield curves exhibited an increase followed by a decrease as a function of OH exposure, with maximum yields at O/C ratios ranging from 0.29 to 0.74. The decrease in SOA yield correlates with an increase in oxygen content and decrease in carbon content, consistent with transitions from functionalization to fragmentation. For a subset of alkane precursors (n-C10, n-C15, and JP-10), maximum SOA yields were estimated to be 0.39, 0.69, and 1.1. In addition, maximum SOA yields correspond with a maximum in the CxHyO+ relative abundance. Measured correlations between OH exposure, O/C ratio, and H/C ratio may enable identification of alkane precursor contributions to ambient SOA.
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U2 - 10.1021/es300274t
DO - 10.1021/es300274t
M3 - Article
C2 - 22534114
AN - SCOPUS:84861116560
SN - 0013-936X
VL - 46
SP - 5430
EP - 5437
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 10
ER -