Substrate-induced multipolar resonances in supported free-electron metal spheres

Abstract

International audienc

Silver and gold nanoparticles in silica matrices: synthesis, properties, and application

“…The methods for the production of the nanoparticles of the individual metals and of the bimetallic nanoparticles are similar: photoreduction, chemical reduction in aqueous media in the presence of stabilizers (polymers, inverse micelles), thermal reduction [30,[74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90]. There is no doubt that the photochemical method for the reduction of nanoparticles and bimetallic nanoparticles from their ions is the most economical and energy-and time-saving in comparison with other methods [29][30][31]77].…”

Monitoring of the Plasmon Resonance of Gold Nanoparticles in Au/TiO2 Catalyst under Oxidative and Reducing Atmospheres

“…For supported gold particles, the situation is intermediate between isolated particles and embedded ones, and the interaction with the substrate also induces a red shift of the absorption resonance, 38 together with the excitation of additional multipolar resonances. 39,40 On the other hand, possible quantum size effect leading to the spill out of the free electron distribution at the surface might be important for particles smaller than 4 nm. 35,41,42 Such effect can give a blue shift of the resonance, as large as ∆λ ) 40 nm for particles as small as 2 nm.…”

Real-Time Investigation of Potassium Growth by Surface Differential Reflectance Spectroscopy

“…We have considered here only the interaction with the silicon dioxide. As we have previously shown, this gives a satisfactory result, although the multipolar effects are in this case slightly reduced [11]. In all the calculations presented here, we have used a Drude expression for the dielectric function of potassium, with a plasma energy equal to 3.8 eV [9] and a damping parameter " ht ± ±1 = 0.4 eV, whose value is supported by photoabsorption experiments on small isolated K clusters [13].…”

“…It has been shown recently that, for an exact treatment of the interaction with the substrate, not only the dipole coupling, but also the multipole coupling (MC) has to be considered, which increases the red-shift of the dipolar resonance and yields additional features due to multipolar resonances. In our case, the slight shoulder around 2.3 eV in the 0.05 and 0.08 nm spectra ± ±although not clearly visible with the scale chosen here ± ± is an effect of this MC with the substrate, which has been discussed in a previous paper [11]. We shall now consider the two first stages, namely the single resonance initially located at 1.9 eV, then shifting to 2.7 eV.…”