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Iodination of gas-phase-generated Ag nanoparticles: Behavior of the two spin orbit components of the AgI exciton in Ag@AgI core-shell nanoparticles

Pedersen, David B. and Wang, Shiliang (2007) Iodination of gas-phase-generated Ag nanoparticles: Behavior of the two spin orbit components of the AgI exciton in Ag@AgI core-shell nanoparticles. JOURNAL OF PHYSICAL CHEMISTRY C, 111 (3). pp. 1261-1267.

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jp066357s

Abstract

Ag nanoparticles, with diameters estimated to be 17 +/- 6 nm, were observed to react readily with I-2 to produce Ag@AgI core-shell nanoparticles. Both spin-orbit components of the exciton associated with the AgI shell were observed in the UV-vis spectra. The band gap of the AgI shell was found to shift to lower energy as the reaction with 12 proceeded and the shell thickness increased. Shell thickness can be varied by controlling the duration of the exposure of the Ag nanoparticles to iodine. The band gap observed for the Ag@AgI nanoparticles was comparable to that expected of a solid AgI nanoparticle with a diameter of 5-6 nm, as estimated using the Brus formula. The difference between this effective diameter and the actual diameter of the particle (17 +/- 6 nm) may be attributable to confinement effects associated with the finite thickness of the AgI shell and/or effects of the Ag core on the AgI shell. The shorter wavelength exciton appeared to be much more sensitive to surface effects, which are pronounced in nanoparticles, and appeared anywhere from 312 to 355 nm. The longer wavelength exciton behaved differently and does not appear to be affected much by such surface effects and therefore seems to be a much more localized electron-hole pair.

Item Type:Article
Subjects:Material Science > Nanochemistry
Material Science > Nanostructured materials
ID Code:3277
Deposited By:Farnush Anwar
Deposited On:15 Jan 2009 13:56
Last Modified:15 Jan 2009 13:56

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