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Center for Excitonics Seminar Series
Tues. November 29, 2011
3:00 PM - 4:00 PM
Haus Conference Room - 36-428
"Spectroscopy of complex molecular systems: Physics on an exciton cake-walk"
Jasper Knoester, Zernike Institute for Advanced Materials, University of
Groningen
abstract
The concept of excitons, collective excited states, is well-known in
solid-state physics. It was first developed by Frenkel in the 1930's to
explain the absorption spectrum of perfect molecular crystals, in which case
the excitons are simple Bloch waves of excitation. Over the years, it has
become apparent that also less regular structures carry delocalized
excitations, which are responsible for many of their electromagnetic
properties and energy transport characteristics. In this presentation, I
will address two classes of such systems. The first class are molecular
J-aggregates, large self-assembled structures containing up to 1000's of
molecules, which play a role in opto-electronic applications and natural
photosynthetic systems. The second class are polypeptides and proteins, in
which case collective vibrations are the excitations of interest. The
irregular nature of these systems and the occurrence of fluctuations in
their host, provide a complex and dynamic landscape in which the excitons
are created, evolve, and decay. I will address the basic physics of these
systems, some of their intriguing properties, and the theoretical tools used
by us to analyse and predict (ultrafast) spectroscopic experiments in the
visible and the infrared used to probe these properties.
bio
Jasper Knoester received his MSc and PhD in Theoretical Physics at the
University of Utrecht, The Netherlands, in 1983 and 1987, respectively.
Currently, he is the Dean of Faculty of Mathematics and Natural Sciences and
Professor of Theoretical Physics at the University of Groningen, The
Netherlands. He conducts his research in the Theory of Condensed Matter
Group at the Zernike Institute for Advanced Materials in optical and
electronic properties of condensed phases, in particular of (bio)molecular
aggregates and conjugated polymers; vibrational dynamics and infrared
spectroscopy of polypeptides and proteins; low-dimensional systems; spin
systems; disorder and localization; QED near dielectric interfaces; light
scattering on photonic crystals, plasmonics.
Light refreshments will be provided
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