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Proceedings Paper

Electron relaxation in lead-salt quantum dots
Author(s): Frank W. Wise; Jeff Harbold; Stephen Clark; Byung-Ryool Hyun
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Paper Abstract

Recent studies of the relaxation of photoexcited electrons in PbSe quantum dots find that the relaxation of electrons from the 1P state to the 1S state occurs on the picosecond time scale, even when the states are more than 10 phonon energies apart. This ultrafast relaxation cannot be explained by mechanisms invoked to explain the absence of a phonon bottleneck in other quantum-dot materials. Linear spectroscopy reveals splitting of the lowest-energy states of PbSe quantum dots, but the splitting is inadequate to account for the ultrafast 1P-to-1S relaxation. We tentatively attribute the splitting to coupling of the equivalent L-valleys from which the quantum-dot states are derived. Fluorescence-line-narrowing experiments exhibit little narrowing, and substantial anti-Stokes fluorescence even at temperatures as low as 15 K. Finally, we observe microsecond-time-scale radiative recombination and resonant energy transfer between quantum dots. The time scale of these processes is consistent with dielectric screening of the electric field in the nanocrystals, which in turn highlights the need for better understanding of the dielectric function of a nanocrystal.

Paper Details

Date Published: 18 August 2005
PDF: 9 pages
Proc. SPIE 5929, Physical Chemistry of Interfaces and Nanomaterials IV, 59290S (18 August 2005); doi: 10.1117/12.617285
Show Author Affiliations
Frank W. Wise, Cornell Univ. (United States)
Jeff Harbold, Cornell Univ. (United States)
Stephen Clark, Cornell Univ. (United States)
Byung-Ryool Hyun, Cornell Univ. (United States)


Published in SPIE Proceedings Vol. 5929:
Physical Chemistry of Interfaces and Nanomaterials IV
Clemens Burda; Randy J. Ellingson, Editor(s)

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