By near-field optics, we characterized the local optical properties of clusters of gold nanoparticles randomly distributed under a 50 nm-thick SiO2 thin film. A local field enhancement is visible above isolated clusters. A few hundred nanometers away from them, we observed a polarization-dependent pattern with elliptical lobes oriented in the incident polarization direction. A simple simulation shows that the observed near-field images can be represented by the sum of the field of an oscillating dipole and the incident field. When the cluster density is larger, the measured near-field images show numerous bright and dark spots. The position of the bright spots does not necessarily coincide with the gold clusters showing the presence of coupling effects between them.
Near-field optical characterization of interacting and non-interacting gold nanoparticles embedded in a silica thin film
De Julian Fernandez C;
2011
Abstract
By near-field optics, we characterized the local optical properties of clusters of gold nanoparticles randomly distributed under a 50 nm-thick SiO2 thin film. A local field enhancement is visible above isolated clusters. A few hundred nanometers away from them, we observed a polarization-dependent pattern with elliptical lobes oriented in the incident polarization direction. A simple simulation shows that the observed near-field images can be represented by the sum of the field of an oscillating dipole and the incident field. When the cluster density is larger, the measured near-field images show numerous bright and dark spots. The position of the bright spots does not necessarily coincide with the gold clusters showing the presence of coupling effects between them.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
