Center for Excitonics
Seminar Series Announcement
The Center for Excitonics is an Energy Frontier Research Center funded by
the
U.S. Department of Energy, Office of Science and Office of Basic Energy
Sciences
The Center for Excitonics invites you to join us at the next seminar of
the
Spring 2010 series. Please forward this information on to others who
might be
interested in attending this and other center seminars.
Title: State-Resolved Exciton Dynamics in Quantum Dots
Presenter: Patanjali Kambhampati
Organization: Department of Chemistry, McGill University
Date: April 15, 2010
Time: 3:00 - 4:00pm
Place: 34-401A (Grier A)
Center URL:
www.rle.mit.edu/excitonics
Seminar URL:
www.rle.mit.edu/excitonics/patanjali-041510.html
Abstract
The semiconductor quantum dot is one of the canonical systems in
nanoscience. Whereas the nanometer size of these materials is obvious, the
richer and more meaningful issue is the presence of quantum confinement
effects conferred by virtue of size. One may qualitatively describe
quantum dot electronic structure like the textbook particle in a sphere.
However, this simple picture misses the vast majority of the processes
which ultimately control the functionality of the quantum dot. Our goal is
to obtain a detailed picture of the rich inner workings of the quantum
dot. We introduce a mixed time/frequency domain ultrafast spectroscopic
approach which we denote State-Resolved Exciton Dynamics. We have applied
this approach to resolve several long standing issues central to quantum
dot science:
1) Hot exciton relaxation dynamics: radiationless transitions on the
nanoscale
2) Optical gain: recovering predictions from theory and revealing new
physics
3) Electronic structure of multiexcitons: creation of an artificial
periodic table
4) electron-phonon interactions: quantizing piezoelectricity
The power of this approach is reflected by our ability to predict aspects
of unrelated experiments, e.g. single dot blinking and multiple exciton
generation.
In addition to the basic science of excitons in nanoscale materials, these
fundamental results have advanced the design principles for a broad range
of applications including: LEDs, lasers, solar cells, THz radiation
sources, piezoelectrics, and non-classical light.
Bio
Patanjali Kambhampati received a B.A. in Chemistry from Carleton College
in 1992, and a Ph.D. in Chemistry from the University of Texas at Austin
in 1998. His doctoral work focused on ultra-high vacuum surface studies of
adsorbate-substrate charge transfer excitations and surface enhanced Raman
scattering under the supervision of Alan Campion. From 1999 – 2001 he was
a Postdoctoral Associate with Paul Barbara, also at the University of
Texas at Austin. His postdoctoral work focused on femtosecond laser
spectroscopy of condensed phase chemical dynamics of the solvated electron
and intramolecular electron transfer. From 2001 – 2003 he was involved in
early phase work in a fiber optic startup based in Los Angeles. At McGill
University, where his group focuses on ultrafast dynamics in quantum dots,
he was an Assistant Professor from 2003 – 2009 and is presently an
Associate Professor.