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Tuesday, November 20

NOTE NEW ROOM:
Manipulation of Exciton Dynamics in Macrocycle
Molecules and Inorganic Semiconductor Nanocrystals

Su Liu, University of Utah, Department of Physics and Astronomy, Salt Lake City
Chemical Sciences Division Seminar
10:00 AM — 11:00 AM, Building 4100 / Room C-301
Contact: Robert W. Shaw (shawrw@ornl.gov), 865.574.4920

Abstract

Electrostatic manipulation of exciton dynamics with external electric fields can be used to study electronic properties of novel material systems such as semiconductor nanocrystals, which may be well suited for future applications in optoelectronic devices. Excitons can be separated and stored in nanocrystals by an applied electric field for several microseconds before being retrieved upon the removal of the electric field. Due to the limited number of trap sites where excitons can be stored, the relative efficiency of exciton manipulation decreases with increasing excitation density. The manipulation of excitons can also be achieved through structural engineering, which controls exciton relaxation through the designed chemical structure. Model molecular systems of monomers and dimers were studied using time-resolved spectroscopy in combination with single molecule spectroscopy to reveal coherent exciton delocalization and incoherent energy transfer in the dimers containing two closely spaced monomers.