<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0035-001X</journal-id>
<journal-title><![CDATA[Revista mexicana de física]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. fis.]]></abbrev-journal-title>
<issn>0035-001X</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Mexicana de Física]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0035-001X2018000500507</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[In-situ monitoring by thermal lens microscopy of a photocatalytic reduction process of hexavalent chromium]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Cedeño]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
<xref ref-type="aff" rid="Aaf"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Plazas-Saldaña]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Gordillo-Delgado]]></surname>
<given-names><![CDATA[F.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Bedoya]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
<xref ref-type="aff" rid="Aaf"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Marín]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Instituto Politécnico Nacional  ]]></institution>
<addr-line><![CDATA[Ciudad de México ]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,University of Campinas  ]]></institution>
<addr-line><![CDATA[Campinas SP]]></addr-line>
<country>Brazil</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,Universidad del Quindío  ]]></institution>
<addr-line><![CDATA[Armenia ]]></addr-line>
<country>Colombia</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>10</month>
<year>2018</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>10</month>
<year>2018</year>
</pub-date>
<volume>64</volume>
<numero>5</numero>
<fpage>507</fpage>
<lpage>511</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0035-001X2018000500507&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0035-001X2018000500507&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0035-001X2018000500507&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Abstract In this work, we describe the application of a micro-spatial thermal lens spectroscopy setup (thermal lens microscope, TLM) with coaxial counter-propagating pump, and probe laser beams, and an integrated passive optical Fabry-Perot, to quantify the Cr-VI concentration in water during a photocatalytic reaction in-situ. A series of test samples was analyzed using the 1.5 diphenil carbazide colorimetric method. A calibration curve was obtained by plotting of the TLM signal as a function of the concentration of Cr(VI) in a range between 0 and 10 &#956;g/L (1 &#120583;g/L = 1 ppb, part per billion), with a detection limit of 53 ng/L (1 ng/L = 1 ppt, part per trillion). A solution of 10 &#120583;g/L Cr(VI) in distillated water was placed into a cell in contact with an iron-incorporated titanium dioxide film, which was previously grown onto a 1 mm thick glass microscope slide by the sol-gel dip-coating technique. The TLM signal was registered as a function of the photocatalysis time measured from the beginning of the process, radiating the film with UV-violet light. The Cr(VI) concentration was determined with the calibration curve and after the first 50 minutes a reduction of 95 % of Cr(VI) was observed, being the chemical reaction kinetic described by a potential time decreasing function.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Thermal lens microscopy]]></kwd>
<kwd lng="en"><![CDATA[photocatalysis]]></kwd>
<kwd lng="en"><![CDATA[hexavalent chromium]]></kwd>
<kwd lng="en"><![CDATA[titanium dioxide]]></kwd>
<kwd lng="en"><![CDATA[42.62.Fi]]></kwd>
<kwd lng="en"><![CDATA[07.88.+y]]></kwd>
<kwd lng="en"><![CDATA[82.80.Kq]]></kwd>
</kwd-group>
</article-meta>
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