Abstract
In this study, we show that supported gold nanoparticles with a given well-defined shape can be produced by laser-assisted growth on substrates based on different materials. For this purpose, gold nanoparticles with average radii ranging from 1.5 to 13 nm, i.e., covering between 0.45 x 10(16) and 5.6 x 10(16) atoms/cm(2), 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 impact 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 mJ/cm(2) have been found. The results of these experiments show that laser-assisted growth is a powerful technique to control the shape of nanoparticles of different materials on different substrates.