TY  - JOUR
AU  - Emanuelsson, Eva U.
AU  - Mentel, Thomas F.
AU  - Watne, Ågot K.
AU  - Spindler, Christian
AU  - Bohn, Birger
AU  - Brauers, Theo
AU  - Dorn, Hans-Peter
AU  - Hallquist, Åsa M.
AU  - Häseler, Rolf
AU  - Kiendler-Scharr, Astrid
AU  - Müller, Klaus Peter
AU  - Pleijel, Håkan
AU  - Rohrer, Franz
AU  - Rubach, Florian
AU  - Schlosser, Eric
AU  - Tillmann, Ralf
AU  - Hallquist, Mattias
TI  - Parameterization of Thermal Properties of Aging Secondary Organic Aerosol Produced by Photo-Oxidation of Selected Terpene Mixtures
JO  - Environmental science & technology
VL  - 48
IS  - 11
SN  - 0013-936X
CY  - Columbus, Ohio
PB  - American Chemical Society
M1  - FZJ-2015-00638
SP  - 6168 - 6176
PY  - 2014
AB  - Formation and evolution of secondary organic aerosols (SOA) from biogenic VOCs influences the Earth’s radiative balance. We have examined the photo-oxidation and aging of boreal terpene mixtures in the SAPHIR simulation chamber. Changes in thermal properties and chemical composition, deduced from mass spectrometric measurements, were providing information on the aging of biogenic SOA produced under ambient solar conditions. Effects of precursor mixture, concentration, and photochemical oxidation levels (OH exposure) were evaluated. OH exposure was found to be the major driver in the long term photochemical transformations, i.e., reaction times of several hours up to days, of SOA and its thermal properties, whereas the initial concentrations and terpenoid mixtures had only minor influence. The volatility distributions were parametrized using a sigmoidal function to determine TVFR0.5 (the temperature yielding a 50% particle volume fraction remaining) and the steepness of the volatility distribution. TVFR0.5 increased by 0.3 ± 0.1% (ca. 1 K), while the steepness increased by 0.9 ± 0.3% per hour of 1 × 106 cm–3 OH exposure. Thus, aging reduces volatility and increases homogeneity of the vapor pressure distribution, presumably because highly volatile fractions become increasingly susceptible to gas phase oxidation, while less volatile fractions are less reactive with gas phase OH.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000336952000015
DO  - DOI:10.1021/es405412p
UR  - https://juser.fz-juelich.de/record/186565
ER  -