Dresden 2006 – wissenschaftliches Programm
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O: Oberflächenphysik
O 26: Particles and clusters I
O 26.11: Vortrag
Dienstag, 28. März 2006, 18:15–18:30, WIL A317
Tailoring the dimensions of colloidal gold nanoparticles by laser irradiation — •F. Vogel, C. Hendrich, F. Hubenthal, and F. Träger — Instiut für Physik and Center for Interdisciplinary Nanostructure Science and Technology - CINSaT, Universität Kassel, Heinrich-Plett-Straße 40, D-34132 Kassel
Colloidal gold nanoparticles (AuNPs) are used in many different fields and, especially for industrial applications, are often needed in large quantities. However, a substantial drawback of most production methods is that the prepared AuNPs exhibit broad size and shape distributions. In this contribution, we present our recent experiments with the objective of tailoring the size of AuNPs in solution with laser light in order to overcome the drawback mentioned above. In our experiments colloidal AuNPs were prepared by wet chemical reduction of HAuCl4. Post-synthesis irradiation with laser light permits tailoring of the dimensions of the nanoparticles by diffusion of surface atoms and, especially at high fluences, removal of atoms. Thus, it is possible to eliminate all particles of undesired sizes and shapes by choosing appropriate photon energies and light intensities.
First experiments on colloidal AuNPs with a mean radius of <r> = (7.5 ± 1.5) nm show a pronounced reduction of the HWHM (half width at half maximum) of the surface plasmon resonance (SPR) from 0.37 eV to 0.21 eV and an increased absorption at higher photon energies by the modified AuNPs. The increase and shift of the SPR to higher photon energies can be attributed to a narrowed shape distribution. Consequences of the laser treatment for the size distribution are under examination.