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<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="methods-article" dtd-version="3.0" xml:lang="en">
<front>
<journal-meta>
<journal-id journal-id-type="publisher">ACP</journal-id>
<journal-title-group>
<journal-title>Atmospheric Chemistry and Physics</journal-title>
<abbrev-journal-title abbrev-type="publisher">ACP</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Atmos. Chem. Phys.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1680-7324</issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/acp-14-9201-2014</article-id>
<title-group>
<article-title>Technical Note: Application of positive matrix factor analysis in heterogeneous kinetics studies utilizing the mixed-phase relative rates technique</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Liu</surname>
<given-names>Y.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Li</surname>
<given-names>S.-M.</given-names>
<ext-link>https://orcid.org/0000-0002-7628-6581</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Liggio</surname>
<given-names>J.</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Air Quality Processes Research Section, Environment Canada, Toronto, M3H 5T4, Canada</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>now at: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China</addr-line>
</aff>
<pub-date pub-type="epub">
<day>08</day>
<month>09</month>
<year>2014</year>
</pub-date>
<volume>14</volume>
<issue>17</issue>
<fpage>9201</fpage>
<lpage>9211</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2014 Y. Liu et al.</copyright-statement>
<copyright-year>2014</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/3.0/">https://creativecommons.org/licenses/by/3.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://acp.copernicus.org/articles/14/9201/2014/acp-14-9201-2014.html">This article is available from https://acp.copernicus.org/articles/14/9201/2014/acp-14-9201-2014.html</self-uri>
<self-uri xlink:href="https://acp.copernicus.org/articles/14/9201/2014/acp-14-9201-2014.pdf">The full text article is available as a PDF file from https://acp.copernicus.org/articles/14/9201/2014/acp-14-9201-2014.pdf</self-uri>
<abstract>
<p>The mixed-phase relative rates approach for determining aerosol particle
organic heterogeneous reaction kinetics is often performed utilizing mass
spectral tracers as a proxy for particle-phase reactant concentration.
However, this approach may be influenced by signal contamination
from oxidation products during the experiment. In the current study, the
mixed-phase relative rates technique has been improved by combining a
positive matrix factor (PMF) analysis with electron ionization aerosol mass
spectrometry (unit-mass resolution), thereby removing the influence of &lt;i&gt;m / z&lt;/i&gt;
fragments from reaction products on the reactant signals. To demonstrate the
advantages of this approach, the heterogeneous reaction between OH radicals
and citric acid (CA) was investigated using a photochemical flow tube
coupled to a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS).
The measured heterogeneous rate constant (&lt;i&gt;k&lt;/i&gt;&lt;sub&gt;2&lt;/sub&gt;) of citric acid toward OH
was
(3.31 ± 0.29) × 10&lt;sup&gt;&amp;minus;12&lt;/sup&gt; cm&lt;sup&gt;3&lt;/sup&gt; molecule&lt;sup&gt;−1&lt;/sup&gt; s&lt;sup&gt;−1&lt;/sup&gt;
at 298 K and (30 ± 3)% relative humidity (RH) and was several times greater
than the results utilizing individual &lt;i&gt;m / z&lt;/i&gt; fragments. This phenomenon was
further evaluated for particulate-phase organophosphates (triphenyl phosphate (TPhP), tris-1,3-dichloro-2-propyl phosphate (TDCPP) and tris-2-ethylhexyl phosphate
(TEHP)), leading to &lt;i&gt;k&lt;/i&gt;&lt;sub&gt;2&lt;/sub&gt; values significantly larger than previously
reported. The results suggest that heterogeneous kinetics can be
significantly underestimated when the structure of the products is highly
similar to the reactant and when a non-molecular tracer is measured with a
unit-mass resolution aerosol mass spectrometer. The results also suggest
that the heterogeneous lifetime of organic aerosol in models can be
overestimated due to underestimated OH uptake coefficients. Finally, a
comparison of reported rate constants implies that the heterogeneous
oxidation of aerosols will be dependent upon a number of factors related to
the reaction system, and that a single rate constant for one system cannot
be universally applied under all conditions.</p>
</abstract>
<counts><page-count count="11"/></counts>
<funding-group>
<award-group id="gs1">
<funding-source>Government of Canada</funding-source>
<award-id>The Chemicals Management Plan</award-id>
</award-group>
<award-group id="gs2">
<funding-source>Government of Canada</funding-source>
<award-id>The Clean Air Regulatory Agenda</award-id>
</award-group>
</funding-group>
</article-meta>
</front>
<body/>
<back>
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