Controlled synthesis and quantum-size effect in gold-coated nanoparticles

H. S. Zhou, I. Honma, H. Komiyama, J. W. Haus

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236 Citations (Scopus)


We have observed enormous shifts of the optical-absorption peak during the reduction of gold-sulfide particles (Au2S) to gold particles. A two-step colloidal method is used for the nanoparticle synthesis. We can explain our findings by assuming the colloidal particles have a gold coating on the surface. This is also consistent with our transmission-electron-microscopy figures, displaying a core-shell structure, and electron-diffraction data. The optical-absorption peak initially shifts toward the red and at later times toward the blue wavelengths. By controlling the initial size of the gold-sulfide particles, the resonance shift is correlated with a theoretical model that includes both quantum confinement and the resonance effects (the so-called surface-plasmon resonance). The use of metal-coated particles with a nonmetallic core material offers two advantages for studying quantum confinement. First, the particles are initially large, and have a large polarizability and consequently a large absorption cross section, and second, the thin metal layer confines the electron in one dimension and can extend itself in the other two dimensions.

Original languageEnglish
Pages (from-to)12052-12056
Number of pages5
JournalPhysical Review B
Issue number16
Publication statusPublished - 1994
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics


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