Chemical interface damping of surfaceplasmon excitation in metal nanoparticles:a study by persistent spectral hole burning

H. Ouacha, C. Hendrich, F. Hubenthal and F. Träger

Institut für Physik and Center for Interdisciplinary Nanostructure Science and Technology - CINSaT, Universität Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany

Received: 7 June 2005
Published online: 22 July 2005

Abstract
We demonstrate that supported gold nanoparticles with a given well-defined shape can be produced by laser-assisted growth. For this purpose, gold nanoparticles with average radii ranging from 1.5 to 13 nm, i.e., coverage between 0.45 × 10¹⁶ and 5.6 × 10¹⁶ atoms/cm², were prepared at room temperature by self-assembly of atoms deposited on quartz and sapphire substrates. For analysis of the samples, the optical spectra of the particles were measured with p-polarized light and photon energies in the range of 1.3 to 3.1 eV. Irradiating the particles during growth with laser light of different wavelengths to stimulate surface plasmon excitation made it possible to stabilize mean axial ratios between 0.19 and 0.98. The influence of the laser fluence on the shape of the nanoparticles was also investigated and shows that the position of the surface plasmon resonance shifts to higher energies as the fluence rises. Optimum growth conditions to shape gold nanoparticles with axial ratios close to unity (spheres) with a relatively low laser fluence of 60 ± 5 mJ/cm² have also been found. The results of our experiments show that laser-assisted growth is a powerfultechnique to control the shape of nanoparticles.

PACS 61.46.+w - 71.45.Gm - 73.22.Lp - 78.67.Bf, © Springer-Verlag 2005

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