RÉSUMÉ
The optical switching of coupled plasmons of silver nanoparticles derivatised with a photoisomerisable azobenzene ligand is presented. It is shown that nanoparticle clusters, linked with an azobenzene dithiol molecule, display switchable optical properties. The photoisomerisation of the linker molecule was used to vary the separation between nanoparticles, which was monitored by changes in the UV-Vis-spectra of the plasmon band of adjacent nanoparticles. A red-shift due to the appearance of a coupled longitudinal plasmon band was observed resulting from the formation of nanoparticle clusters. The maximum absorbance wavelength of this secondary plasmon band was altered by isomerisation of the linker and the spectral changes observed were in good agreement with theory and earlier measurements for gold. Evidence of energy transfer between a nanoparticle and an azobenzene terminated monothiol attached to it was also observed in the UV-Vis spectra.
Sujet(s)
Composés azoïques/composition chimique , Nanoparticules/composition chimique , Optique et photonique , Argent/composition chimique , Résonance plasmonique de surface , Composés azoïques/synthèse chimique , Composés azoïques/effets des radiations , Transfert d'énergie , Or/composition chimique , Isomérie , Ligands , Microscopie électronique à transmission/méthodes , Modèles moléculaires , Structure moléculaire , Photochimie , Sensibilité et spécificité , Spectrophotométrie UV/méthodes , Propriétés de surface , Rayons ultravioletsRÉSUMÉ
A new method for the preparation of metal nanoparticles in organic media is proposed. This is based on the formation of metal-carbon bonds after reduction of the corresponding diazonium derivative of the capping ligand. The particles are very stable due to the strong metal-ligand covalent bond, and the proposed method appears to be an alternative for the preparation of monolayer-protected metal nanoparticles when the formation of metal-sulfur or metal-nitrogen bonds needs to be avoided.
