Brewster angle technique to study metal nanoparticle distributions in dielectric matrix

We report experimental results obtained by means of the Brewster angle technique on samples constituted by Pb and Sn nanoparticles embedded in an amorphous SiO matrix. The extended comparison with different effective medium models gives clear indications on (i) the structural composition of the samples and (ii) the spatial distribution of the metallic particles in these systems, pointing to a quasi‐two‐dimensional arrangemen

Quantum confinement effects above the band gap in Ge quantum dots

edited by M. Scheffler and R. Zimmermann, World Scientific Publishing, Singapore, 199

Ellipsometric study of optical properties of liquid Ga nanoparticles

The investigation of the optical properties of liquid Ga nanoparticles embedded in a dielectric matrix by means of spectroscopic ellipsometry is reported. The particles, which have the shape of truncated spheres and a radius which is varied in a controlled way between 5 and 16 nm, are grown by the evaporation-condensation technique. The results are discussed in terms of the current effective medium models and give new information on the distribution of the particles in the matrix as well as on their optical properties. A resonance peak due to the plasmon-polariton electron excitations in the particles is observed in the imaginary part of the effective dielectric function of the layer. Its position shifts to higher photon energies and the half width of the resonance increases with the decrease of the particle size. The dielectric function of the particles is parametrized using the Drude dispersion equation. The obtained electron damping parameter increases with the decrease of the particle size in accordance with the predictions of the size theories of the optical properties of small particles

Harmonic generation in metallic nanoscale systems

The nonlinear interaction between materials based on metallic nanoparticles and strong electric fields such as the one produced by laser pulsed radiation produces significant response amplification whenever system resonances are being excited. In particular, second harmonic radiation excited by pulsed lasers in the near infrared can be generated in these systems with efficiencies far exceeding those of corresponding bulk materials. In this paper, experimental results are presented for two different physical systems, namely Au nanoparticles in aqueous solutions and Ga nanoparticle monolayers embedded in dielectric matrices with mean radii in the nanometer range. Measurements of second harmonic generated radiation in the two systems in different geometries and their dependence on various physical parameters illustrate the central role of surface plasmon resonances. This experimental evidence is reasonably corroborated by ad hoc models

Study of nano-clusters crystalline stability versus temperature and quantum effects

edited by D.J.Lookwood, World Scientific Publishing, Singapor

Nonlinear opticl investigations of metal nanoparticle composites

Nonlinear optical properties of metal nanoparticles have been investigated at different excitation wavelengths as a function of particle size. The second order nonlinear response has been determined in two different nanometric systems, a) Gallium nanoparticle monolayers embedded in dielectric matrix producing collinear second harmonic generation, and b) Au/water colloids giving rise to diffuse hyper-Rayleigh scattering. Modeling of the mechanisms involved provides a key to the interpretation of the dependence of the signal from temperature and size