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<article language="en">
	<journal>
		<journal_title>Atmospheric Chemistry and Physics Discussions</journal_title>
		<journal_url>www.atmos-chem-phys-discuss.net</journal_url>
		<issn>1680-7367</issn>
		<eissn>1680-7375</eissn>
		<volume_number>9</volume_number>
		<issue_number>1</issue_number>
		<publication_year>2009</publication_year>
	</journal>
	<doi>10.5194/acpd-9-1273-2009</doi>
	<article_url>http://www.atmos-chem-phys-discuss.net/9/1273/2009/</article_url>
	<abstract_html>http://www.atmos-chem-phys-discuss.net/9/1273/2009/acpd-9-1273-2009.html</abstract_html>
	<fulltext_pdf>http://www.atmos-chem-phys-discuss.net/9/1273/2009/acpd-9-1273-2009.pdf</fulltext_pdf>
	<start_page>1273</start_page>
	<end_page>1300</end_page>
	<publication_date>2009-01-15</publication_date>
	<article_title content_type="html">Kinetic modeling of nucleation experiments involving SO&lt;sub&gt;2&lt;/sub&gt; and OH: new insights into the underlying nucleation mechanisms</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>H. Du</name>
			<email>huadu@asrc.cestm.albany.edu</email>
		</author>
		<author numeration="2" affiliations="1">
			<name>F. Yu</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">Atmospheric Sciences Research Center, State University of New York at Albany, Albany, NY, 12203, USA</affiliation>
	</affiliations>
	<abstract content_type="html">Nucleation is an important source of atmospheric aerosols which have
      significant climatic and health implications. Despite intensive
      theoretical and field studies during past decades, the dominant
      nucleation mechanism in the lower troposphere remains to be
      mysterious. Several recent laboratory studies on atmospheric
      nucleation may shed light on this important problem. However, the most
      interesting finding from those studies was based on the
      H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; concentration whose accuracy has not yet been
      evaluated by any other methods. Moreover, the threshold
      H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt; concentration needed to reach the same degree of
      nucleation reported by two separate nucleation studies varies by about
      one order of magnitude. In this study, we apply a recently updated
      kinetic nucleation model to study the nucleation phenomena observed in
      those recent experiments. We show that the H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;
      concentration can be estimated with a higher level of accuracy with
      the kinetic model by constraining the simulated particle size
      distributions with observed ones. We find that the H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;
      concentration was underestimated in those studies by a factor of ~2 to 4. More
      importantly, by comparing the derived thermodynamic
      properties associated with the nucleation process, we conclude that
      different unknown species may participate in the two separate
      nucleation experimental studies, which may explain the large
      difference in the reported threshold H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;
      concentration. Although the unknown species involved has yet to be
      identified, the derived values of thermodynamic properties can serve
      as a valuable guideline for the search of their chemical identities
      using advanced quantum-chemical approaches.</abstract>
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</article>

