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Center for Excitonics Seminar Series
Thursday, October 11, 2012
RLE Conference Room - 36-428
3:00 - 4:00pm
Exciton Dynamics and Structural Investigations of Singlet Fission in Molecular Solids
Michael Wasielewski -Department of Chemistry and Argonne-Northwestern Solar Energy
Research (ANSER) Center, Northwestern University
Abstract:
abstract: We are examining new dye molecules, which undergo singlet fission (SF),
using guidance from electronic structure calculations to assure the requisite
relationships between molecular singlet and triplet energy levels. We are preparing
hierarchical assemblies from these chromophores, starting from covalent dimers and
trimers, then developing supramolecular assemblies, and engineered crystalline materials
to investigate SF in bulk, ordered materials. We are using femtosecond transient
spectroscopy as well as time-resolved electron paramagnetic resonance spectroscopy to
characterize the SF mechanism and the factors that determine its efficiency at time scales
down to 100 fs. We are also using X-ray diffraction to investigate the single crystal
structures of these materials and X-ray scattering on their thin polycrystalline solid
films to determine how their structures correlate with their ability to carry out SF. Our
results suggest that a p-p slip-stacked geometry is important for maximizing SF
efficiency.io
bio Professor Wasielewski received his Bachelor of Science (1971) and Ph.D. (1975)
degrees from the University of Chicago. Following his graduate work, he was a postdoctoral
fellow at Columbia University. He then joined the scientific staff of Argonne National
Laboratory, where he rose through the ranks to become Group Leader of the Molecular
Photonics Group. In 1994, he joined the faculty of Northwestern University, where he is
currently the Clare Hamilton Hall Professor of Chemistry. He served as Chair of the
Chemistry Department at Northwestern from 2001-2004. He is currently the Director of the
Argonne-Northwestern Solar Energy Research (ANSER) Center, which is a DOE Energy Frontier
Research Center, headquartered at Northwestern. Professor Wasielewski's research
focuses on light-driven charge generation and transport in molecules and supramolecular
materials, artificial photosynthesis, molecular systems for solar fuels and electricity,
molecular electronics, spin dynamics, spintronics, and time-resolved optical and EPR
spectroscopy. His research has resulted in over 410 publications. Professor Wasielewski
was elected a Fellow of the American Association for the Advancement of Science in 1995,
and has held numerous distinguished lectureships and fellowships. Among Professor
Wasielewski's recent awards are the 2012 Arthur C. Cope Scholar Award of the American
Chemical Society, the 2008 Porter Medal for Photochemistry, the 2006 James Flack Norris
Award in Physical Organic Chemistry of the American Chemical Society, and the 2004
Photochemistry Research Award of the Inter-American Photochemical Society.
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