[Back]

J. Ofner, H.-U. Krüger, H. Grothe, P. Schmitt-Kopplin, K. Whitmore, C. Zetzsch:
"Physico-chemical characterization of SOA derived from catechol and guaiacol - a model substance for the aromatic fraction of atmospheric HULIS";
Atmospheric Chemistry and Physics, 11 (2011), 1; 1 - 15.

Secondary organic aerosol (SOA) was produced
from the aromatic precursors catechol and guaiacol by reaction
with ozone in the presence and absence of simulated
sunlight and humidity and investigated for its properties as a
proxy for HUmic-LIke Substances (HULIS). Beside a small
particle size, a relatively low molecular weight and typical
optical features in the UV/VIS spectral range, HULIS contain
a typical aromatic and/or olefinic chemical structure and
highly oxidized functional groups within a high chemical diversity.
Various methods were used to characterize the secondary
organic aerosols obtained: Fourier transform infrared
spectroscopy (FTIR) demonstrated the formation of several
carbonyl containing functional groups as well as structural
and functional differences between aerosols formed at different
environmental conditions. UV/VIS spectroscopy of
filter samples showed that the particulate matter absorbs far
into the visible range up to more than 500 nm. Ultrahigh
resolved mass spectroscopy (ICR-FT/MS) determined O/Cratios
between 0.3 and 1 and observed m/z ratios between 200
and 450 to be most abundant. Temperature-programmedpyrolysis
mass spectroscopy (TPP-MS) identified carboxylic
acids and lactones/esters as major functional groups. Particle
sizing using a condensation-nucleus-counter and differentialmobility-
particle-sizer (CNC/DMPS) monitored the formation
of small particles during the SOA formation process.Particle imaging, using field-emission-gun scanning electron
microscopy (FEG-SEM), showed spherical particles, forming
clusters and chains. We conclude that catechol and guaiacol
are appropriate precursors for studies of the processing
of aromatic SOA with atmospheric HULIS properties on the
laboratory scale.

http://dx.doi.org/10.5194/acp-11-1-2011