Colloidal dispersions of gold rods: Synthesis and optical properties

Bianca M.I. Van Der Zande, Marcel R. Böhmer, Lambertus G.J. Fokkink, Christian Schönenberger

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Colloidal dispersions of rod-shaped gold particles are obtained by electrodeposition of gold in the nanopores of anodized alumina attached to a conductive support followed by dissolution of the alumina and release of the rods from the support. Coagulation is prevented by steric repulsion due to adsorption of poly-(vinylpyrrolidone) on the gold surface. The synthesis method presented is suitable for the preparation of dispersions of nearly monodisperse colloidal gold rods with adjustable aspect ratio L/d in the range 1.8<L/d<49. The length, L, is tuned between 39 and 729 nm, and the diameter, d, is between 12 and 22 nm. The absorbance spectra of randomly oriented colloidal gold rods display a transverse and a longitudinal resonance contribution. With increasing aspect ratio, the transverse resonance shows a small shift to shorter wavelengths, while the longitudinal resonance shifts into the near-infrared regime. The positions of the absorbance maxima agree with the predictions of the Gans theory.

Original languageEnglish
Pages (from-to)451-458
Number of pages8
Issue number2
Publication statusPublished - 25 Jan 2000
Externally publishedYes

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