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@ARTICLE{Flores:185510,
author = {Flores, J. M. and Zhao, Defeng and Segev, L. and Schlag, P.
and Kiendler-Scharr, A. and Fuchs, H. and Watne, Å. K. and
Bluvshtein, N. and Mentel, Th. F. and Hallquist, M. and
Rudich, Y.},
title = {{E}volution of the complex refractive index in the {UV}
spectral region in ageing secondary organic aerosol},
journal = {Atmospheric chemistry and physics},
volume = {14},
number = {11},
issn = {1680-7324},
address = {Katlenburg-Lindau},
publisher = {EGU},
reportid = {FZJ-2014-06937},
pages = {5793 - 5806},
year = {2014},
abstract = {The chemical and physical properties of secondary organic
aerosol (SOA) formed by the photochemical degradation of
biogenic and anthropogenic volatile organic compounds (VOC)
are as yet still poorly constrained. The evolution of the
complex refractive index (RI) of SOA, formed from purely
biogenic VOC and mixtures of biogenic and anthropogenic VOC,
was studied over a diurnal cycle in the SAPHIR photochemical
outdoor chamber in Jülich, Germany. The correlation of RI
with SOA chemical and physical properties such as oxidation
level and volatility was examined. The RI was retrieved by a
newly developed broadband cavity-enhanced spectrometer for
aerosol optical extinction measurements in the UV spectral
region (360 to 420 nm). Chemical composition and volatility
of the particles were monitored by a high-resolution
time-of-flight aerosol mass spectrometer, and a volatility
tandem differential mobility analyzer. SOA was formed by
ozonolysis of either (i) a mixture of biogenic VOC
(α-pinene and limonene), (ii) biogenic VOC mixture with
subsequent addition of an anthropogenic VOC (p-xylene-d10),
or (iii) a mixture of biogenic and anthropogenic VOC. The
SOA aged by ozone/OH reactions up to 29.5 h was found to be
non-absorbing in all cases. The SOA with p-xylene-d10 showed
an increase of the scattering component of the RI correlated
with an increase of the O / C ratio and with an increase in
the SOA density. There was a greater increase in the
scattering component of the RI when the SOA was produced
from the mixture of biogenic VOCs and anthropogenic VOC than
from the sequential addition of the VOCs after approximately
the same ageing time. The increase of the scattering
component was inversely correlated with the SOA volatility.
Two RI retrievals determined for the pure biogenic SOA
showed a constant RI for up to 5 h of ageing. Mass spectral
characterization shows the three types of the SOA formed in
this study have a significant amount of semivolatile
components. The influence of anthropogenic VOCs on the
oxygenated organic aerosol as well as the atmospheric
implications are discussed.},
cin = {IEK-8},
ddc = {550},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {233 - Trace gas and aerosol processes in the troposphere
(POF2-233)},
pid = {G:(DE-HGF)POF2-233},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000337803100030},
doi = {10.5194/acp-14-5793-2014},
url = {https://juser.fz-juelich.de/record/185510},
}