Event
ECE Special Seminar: Exitons & Plasmons as Probes of Ultrafast Dynamics
Monday, April 9, 2012
11:00 a.m.
UMERC, Building # 223, Rm. 1207
Carrie Hilmer
301 405 4471
chilmer@umd.edu
Excitons in Semiconductor Nanocrystals and Plasmons in Metal Nanoparticles as Probes of Ultrafast Dynamics
Speaker: Dr. Matthew Pelton, Argonne National Laboratories
Location: University of Maryland, Energy Research Facility (building 223), Rm. 1207
Time: Monday April 9, 2012 at 11:00 AM
Abstract: Semiconductor nanocrystals and noble-metal nanoparticles exhibit strong, tunable optical resonances, the first due to quantum-confined electron-hole pairs, or excitons, and the second due to collective electron oscillations, or plasmons. In both cases, the resonances are sensitive to the states of electrons in the nanoparticles, allowing them to be used as sensitive probes of ultrafast dynamics. For example, we can monitor the separation and localization of charges in semiconductor nanocrystal heterostructures and small, ligand-stabilized metal clusters; understanding these processes is important for use of these materials in light-emitting devices and in photovoltaic devices. Ultrafast optical measurements also enable the measurement of mechanical vibrations in metal nanoparticles and the damping of these vibrations, of importance for the development of vibration-based mass sensors. The much faster damping of the plasmon oscillations themselves can also be determined, setting a lower limit to the losses experienced in any plasmonic application. Finally, the spectra of plasmon resonances in metal nanoparticles are predicted to be highly modified when they are coupled to excitons in individual semiconductor nanocrystals, with the potential to produce strong optical nonlinearities on the nanometer scale (and, perhaps, at the single-photon level) and to enable novel single-particle spectroscopies.
Biographic sketch: Matthew Pelton received a B.A.Sc. in Engineering Physics from the University of Toronto in 1996 and a Ph.D. in Applied Physics from Stanford University in 2002. Following postdoctoral positions at the Royal Institute of Technology in Sweden and at the University of Chicago, he joined the Center for Nanoscale Materials at Argonne National Laboratory, where he has been a scientific staff member since 2006.
