<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-7">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Aptos;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
font-size:11.0pt;
font-family:"Aptos",sans-serif;
mso-ligatures:standardcontextual;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#467886;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Aptos",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:11.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="#467886" vlink="#96607D" style="word-wrap:break-word">
<div class="WordSection1">
<p style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:15.0pt;margin-left:0in">
<span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#131314">Gu, Shan, Khalaj, Farzaneh, Perraud, Veronique, and Faiola, Celia L., Emerging investigator series: secondary organic aerosol formation from photooxidation of acyclic terpenes in
an oxidation flow reactor, Environ. Sci.: Processes Impacts, Advance Article, 2024,
</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><a href="http://dx.doi.org/10.1039/D4EM00063C">http://dx.doi.org/10.1039/D4EM00063C</a><span style="color:#131314">. </span><o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-family:"Calibri",sans-serif">Abstract</span></b><span style="font-family:"Calibri",sans-serif">. One major challenge in predicting secondary organic aerosol (SOA) formation in the atmosphere is incomplete representation
of biogenic volatile organic compounds (BVOCs) emitted from plants, particularly those that are emitted as a result of stress – a condition that is becoming more frequent in a rapidly changing climate. One of the most common types of BVOCs emitted by plants
in response to environmental stress are acyclic terpenes. In this work, SOA is generated from the photooxidation of acyclic terpenes in an oxidation flow reactor and compared to SOA production from a reference cyclic terpene – á-pinene. The acyclic terpenes
used as SOA precursors included â-myrcene, â-ocimene, and linalool. Results showed that oxidation of all acyclic terpenes had lower SOA yields measured after 4 days photochemical age, in comparison to á-pinene. However, there was also evidence that the condensed
organic products that formed, while a smaller amount overall, had a higher oligomeric content. In particular, â-ocimene SOA had higher oligomeric content than all the other chemical systems studied. SOA composition data from ultra-high performance liquid chromatography
with electrospray ionization mass spectrometry (UHPLC-ESI-MS) was combined with mechanistic modeling using the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) to explore chemical mechanisms that could lead to this oligomer
formation. Calculations based on composition data suggested that â-ocimene SOA was more viscous with a higher glass transition temperature than other SOA generated from acyclic terpene oxidation. This was attributed to a higher oligomeric content compared
to other SOA systems studied. These results contribute to novel chemical insights about SOA formation from acyclic terpenes and relevant chemistry processes, highlighting the importance of improving underrepresented biogenic SOA formation in chemical transport
models.<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a href="https://sites.google.com/site/pamwiki/publications-using-the-pam-oxidation-flow-reactor?authuser=0">PAM Wiki - Publications Using the PAM Oxidation Flow Reactor (google.com)</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:#464646;background:white">Simonen, P., Dal Maso, M., Prauda, P., Hoilijoki, A., Karppinen, A., Matilainen, P., Karjalainen, P., and Keskinen, J.: Estimating errors in vehicle secondary
aerosol production factors due to oxidation flow reactor response time, Atmos. Meas. Tech., 17, 3219–3236,
<a href="https://doi.org/10.5194/amt-17-3219-2024">https://doi.org/10.5194/amt-17-3219-2024</a>, 2024.</span><span style="font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p style="margin-top:0in;background:white"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:black">Abstract.
</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#464646">Oxidation flow reactors used in secondary aerosol research do not immediately respond to changes in the inlet concentration of precursor gases because of their broad transfer
functions. This is an issue when measuring the vehicular secondary aerosol formation in transient driving cycles because the secondary aerosol measured at the oxidation flow reactor outlet does not correspond to the rapid changes in the exhaust flow rate.
Since the secondary aerosol production factor is determined by multiplying the secondary aerosol mass by the exhaust flow rate, the misalignment between the two leads to incorrect production factors. This study evaluates the extent of the error in production
factors due to oxidation flow reactor transfer functions using synthetic and semi-synthetic exhaust emission data. It was found that the transfer-function-related error could be eliminated when only the total production factor of the full cycle was measured
using constant-volume sampling. For shorter segments within a driving cycle, a narrower transfer function led to a smaller error. Even with a narrow transfer function, the oxidation flow reactor could report production factors that were more than 10 times
higher than the reference production factors if the segment duration was too short.<o:p></o:p></span></p>
<p class="MsoNormal"><a href="https://sites.google.com/site/pamwiki/publications-using-other-oxidation-flow-reactors">PAM Wiki - Publications Using Other Oxidation Flow Reactors (google.com)</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="mso-ligatures:none">Andrew Lambe<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ligatures:none">Principal Scientist<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ligatures:none">Aerodyne Research, Inc. <o:p>
</o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</body>
</html>