Optical absorption of submonolayer gold films: Size dependence of ϵround in small island particles

Spectroellipsometric characterization of plasma-deposited Au/SiO2 nanocomposite films

“…The decreasing height of the peak at ϳ425 nm with decreasing a is due to a decrease in the imaginary part of ⑀ inter (⑀ inter Љ ). This trend has also been observed by Yamaguchi et al, 62 however, it is in disagreement with the calculations of Quinten 44 and Kreibig, 46 both of whom obtained an increase in ⑀ inter Љ with decreasing a. The optical constants determined from ellipsometric measurements should be more reliable than those calculated from a KK analysis of extinction spectra since KK integrals have to be approximated in the spectral regions where measured data are not available.…”

Two dimensional dipolar coupling in monolayers of silver and gold nanoparticles on a dielectric substrate

“…First we combine Maxwell Garnett (MG) and Bruggeman (BRUG) theories in dimension n which, as discussed below, we found to be a good compromise for taking into account both short range (local field) and long range (dipole-dipole interaction) dipolar effects. Second, in the 2D case, we considered the interaction of NPs on a substrate, using the dipole image modelling previously developed for small metallic islands 10 .…”

“…Metal nanoparticles (NPs) are widely used in plasmonics 1 , surface enhanced scattering 2 , bio-imaging 3 , nanomedicine 4 and quantum optics 5 , because of their resonant optical properties due to surface plasmons (SP), resulting from the competition between the enhanced local field and the long range interparticle dipolar interactions 6,7 . The spectral position of the surface plasmon (SP) resonance of NPs is known 8 to depend mainly on the size, the shape, the interparticle distances and the dielectric constant of the surrounding medium (nature of ligands, solvents and substrate) 9,10 . The notion of effective medium becomes then essential 6 .…”

Temperature dependence of the surface plasmon resonance of Au/SiO2 nanocomposite films

“…4 The particle-size dependence of the interband transition edge is less clear and has generally been described in terms of surface stress-induced changes of the lattice constant and the reduced coordination of the surface atoms. 5,6 The effect of the latter is a narrowing of the valence band 7,8 and a shift of the center of gravity to lower energy, 9 although the observed shift in small particles is to higher energy as a consequence of particle charging. 10 The former is based on the observed lattice constant changes in gold particles 11 and corresponding changes expected in the electronic band structure.…”