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Proceedings Paper

Ultrafast electronic relaxation in gold (I) sulfide nanoparticles
Author(s): Christian D. Grant; Thaddeus Jude Norman; Todd Morris; Greg Szulczewski; Jin Z. Zhang
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Paper Abstract

Ultrafast electronic relaxation dynamics in Au2S colloidal nanoparticles have been studied using fs transient absorption spectroscopy. The electronic absorption spectrum of the nanoparticles exhibits a broad featureless absorption with increasing intensity from the near-IR into the visible and UV, indicating that Au2S is an indirect bandgap semiconductor. The electronic relaxation dynamics have been measured with 390 nm excitation and probing at 790 and 850 nm. The transient absorption decay profiles can be fit to a double exponential with time constants of 600 fs and 23 ps. The fast decay can be assigned to trapping of electrons from the conduction band to shallow trap states or from shallow traps to deep traps, while the long decay is assigned to recombination from shallow or deep trap states. The overall fast relaxation can be attributed to a high density of intrinsic or surface trap states. This fast decay is non-radiative and consistent with no observable luminescence at room temperature. EXAFS data show a 20% decrease in the first coordination shell for nanoparticles relative to bulk, which suggests a large number of surface dangling bounds that can contribute to a high density of surface trap states.

Paper Details

Date Published: 15 November 2002
PDF: 7 pages
Proc. SPIE 4807, Physical Chemistry of Interfaces and Nanomaterials, (15 November 2002); doi: 10.1117/12.451240
Show Author Affiliations
Christian D. Grant, Univ. of California/Santa Cruz (United States)
Thaddeus Jude Norman, Univ. of California/Santa Cruz (United States)
Todd Morris, Univ. of Alabama (United States)
Greg Szulczewski, Univ. of Alabama (United States)
Jin Z. Zhang, Univ. of California/Santa Cruz (United States)


Published in SPIE Proceedings Vol. 4807:
Physical Chemistry of Interfaces and Nanomaterials
Jin Z. Zhang; Zhong L. Wang, Editor(s)

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