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<DIV align=center><FONT face=Arial size=2><FONT size=3><STRONG><SPAN lang=ES-AR
style="COLOR: black; FONT-FAMILY: Arial; mso-ansi-language: ES-AR">Seminarios
del Dpto. de Química Inorgánica, Analítica y Química Física /
INQUIMAE</SPAN></STRONG><SPAN
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align=center><FONT size=3><STRONG><SPAN lang=ES-AR
style="COLOR: black; FONT-FAMILY: Arial; mso-ansi-language: ES-AR">FCEyN -
Universidad de Buenos Aires</SPAN></STRONG><SPAN
style="FONT-FAMILY: Arial"><o:p></o:p></SPAN></FONT></P>
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align=center><STRONG><SPAN lang=ES-AR
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href="http://www.qi.fcen.uba.ar/es"><FONT
size=3>http://www.qi.fcen.uba.ar/es</FONT></A></SPAN></STRONG><SPAN
style="FONT-FAMILY: Arial"><FONT size=3> <o:p></o:p></FONT></SPAN></P>
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align=center><FONT size=4><STRONG><SPAN lang=ES-AR
style="COLOR: black; FONT-FAMILY: Arial; mso-ansi-language: ES-AR">1er.
Cuatrimestre, 2006</SPAN></STRONG><SPAN
style="FONT-FAMILY: Arial"><o:p></o:p></SPAN></FONT></P>
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<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"
align=center> Miercoles 26 de Abril, 13h</SPAN></STRONG></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"
align=center><FONT size=3><SPAN style="FONT-FAMILY: Arial">Aula de Seminarios
del Departamento de Química Inorgánica, Analítica y Química Física, FCEyN,
UBA</SPAN><o:p></o:p></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"
align=center><SPAN style="FONT-FAMILY: Arial"><FONT size=3>Ciudad Universitaria,
Pabellón II, Piso 3<o:p></o:p></FONT></SPAN></P>
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size=3> </FONT></o:p></SPAN><SPAN style="FONT-FAMILY: Arial"><o:p><FONT
size=3> </FONT></o:p></SPAN></P>
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align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: Arial"><o:p><FONT
size=2></FONT> <STRONG> </STRONG></P>
<P align=center><FONT size=4><STRONG>Daniel Kuroda</STRONG></FONT></P>
<P align=center><FONT size=4>Department of Chemistry, University of
Florida</FONT></P>
<P align=center><FONT size=4>Gainesville, Fl, 32611-7200
</FONT></P></o:p></SPAN>
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align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: Arial"><o:p><FONT
size=4><STRONG>
</STRONG> </FONT></o:p></SPAN><B style="mso-bidi-font-weight: normal"><SPAN
style="FONT-SIZE: 14pt; FONT-FAMILY: Arial"><B><FONT size=4>Controlling
Fluorescence Quantum Efficiency With Femtosecond Laser Pulses</FONT>
</B></SPAN></B></P>
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align=center><B style="mso-bidi-font-weight: normal"><SPAN
style="FONT-SIZE: 14pt; FONT-FAMILY: Arial"><B><I></I></B></SPAN></B> </P>
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align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: Arial"><FONT
face=Helvetica><FONT face=Arial size=3></FONT></FONT></SPAN> </P>
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align=center><SPAN style="FONT-SIZE: 14pt; FONT-FAMILY: Arial"><FONT
face=Helvetica><FONT face=Arial size=3> We present here the coherent
control of the fluorescence quantum efficiency of Rhodamine 6G in solution.
</FONT></P>
<P align=justify><FONT face=Arial size=3> In this work we
demonstrate control over solution photochemistry using a novel tool based on the
coherent properties of the excitation field. To achieve control over a
photochemical process, ultrafast pulses with a particular time and frequency
relationship are needed. These pulses are intrinsically defined by the target
potential energy surfaces. Since full knowledge of the required molecular
properties is unattainable, optimization algorithms with feedback loops have
been used to find the excitation electric field leading to the control of the
process. </FONT></P>
<P align=justify><FONT size=3><FONT face=Arial> In our experiments,
a liquid crystal pulse shaper is used to modulate the phase of the excitation
pulse, and a closed loop genetic algorithm searches for the best pulse to
control the system. Using fluorescence and second harmonic generation as
feedback signals, we successfully control the fluorescence quantum efficiency of
Rhodamine 6G in solution. Through the analysis of the excitation pulses we are
able to obtain molecular information about Rhodamine 6G.</FONT>
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