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color="#000000"><b>Seminar on</b></font></div>
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<div align="center"><font face="Times New Roman"
color="#000000"><b>Modern Optics and Spectroscopy</b></font></div>
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<div align="center"><font face="Times New Roman"
color="#000000"><i><b>Thiophene photophysics:</b></i></font></div>
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color="#000000"><i><b> oligomers, dendrimers, and
polymers</b></i></font></div>
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color="#000000"><i><b><br></b></i></font></div>
<div align="center"><font face="Times New Roman"
color="#000000"><b>David Blank</b>,</font></div>
<div align="center"><font face="Times New Roman"
color="#000000">University of Minnesota</font></div>
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<div align="center"><font face="Times New Roman"
color="#000000">Tuesday, April 14, 2009</font></div>
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<div align="center"><font face="Times New Roman" color="#000000">12:00
- 1:00 p.m.</font></div>
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color="#000000">Conjugated organic systems have been demonstrated as
successful primary components in organic optical and electronic
devices such as photovoltaics. These materials offer some significant
potential advantages in term of cost and processing over the
traditional alternatives, but their performance has yet to become
competitive. Using a variety of ultrafast time-resolved electronic
spectroscopies, including pump-probe, time resolved fluorescence, and
2-color 3-pulse photon echos, we have investigated the dynamics of
light absorption, molecular relaxation, and energy (exciton) migration
in a range of thiophene based systems. The substituted oligomers and
dendrimers offer well defined structures for study while the series of
size selected polymers includes the typical distribution of molecular
sizes found in actual devices. These systems span the range from
molecular excited states that are the same size as the molecule to
molecules that are much larger than the excitation (exciton). Once the
molecular dimensions exceeds the exciton size, coupled relaxation and
migration of the exciton (intramolecular energy transfer) becomes a
key aspect of the dynamics.</font></div>
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<div align="center"><font face="Times New Roman" color="#000000">Grier
Room, MIT Bldg 34-401</font></div>
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color="#000000">Refreshments served after the lecture</font></div>
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