Optical response of Ag-Au bimetallic nanoparticles to electron storage in aqueous medium

Date
2008
Advisor
Instructor
Source Title
Journal of Nanoscience and Nanotechnology
Print ISSN
1533-4880
Electronic ISSN
Publisher
Volume
8
Issue
6
Pages
3003 - 3007
Language
English
Type
Article
Journal Title
Journal ISSN
Volume Title
Abstract

Composition and structure dependence of the shift in the position of the surface plasmon resonance band upon introduction of NaBH 4 to aqueous solutions of gold and silver nanoparticles are presented. Silver and gold nanoalloys in different compositions were prepared by co-reduction of the corresponding salt mixtures using sodium citrate as the reducing agent. After addition of NaBH 4 to the resultant nanoalloys, the maximum of their surface plasmon resonance band, ranging between that of pure silver (ca. 400 nm) and of pure gold (ca. 530 nm), is blue-shifted as a result of electron storage on the particles. The extent of this blue shift increases non-linearly with the mole fraction of silver in the nanoparticle, parallel to the trends reported previously for both the frequency and the extinction coefficient of the plasmon band shifts. Gold(core)@silver(shell) nanoparticles were prepared by sequential reduction of gold and silver, where addition of NaBH 4 results in relatively large spectral shift in the plasmon resonance band when compared with the nanoalloys having a similar overall composition. The origin of the large plasmon band shift in the core-shell is related with a higher silver surface concentration on these particles. Hence, the chemical nature of the nanoparticle emerges as the dominating factor contributing to the extent of the spectral shift as a result of electron storage in bimetallic systems. Copyright © 2008 American Scientific Publishers All rights reserved.

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Keywords
Core-shell structure, Gold and silver nanoparticles, Spectral shifts, Aqueous medium, Bi-metallic nanoparticles, Charge storage, Electron storage, Optical responses, Structure dependence, Gold, Surface plasmon resonance, Silver
Citation
Published Version (Please cite this version)