1,721,029 research outputs found
Optical absorption in ZrO2-x-C nanocomposite films on polymer substrates: application of an effective medium theory
No full textFilms consisting of amorphous carbon dispersed in tetragonal nanocrystalline zirconia were
characterized for their optical properties by reflectance measurements. The optical constants of
each component of the composite have been extracted; the experimental reflectance spectra have
been fitted to Maxwell-Garnett effective medium theory, leading to the effective dielectric
constants of the film. Absorption is characterized by the band gap, the energy and lifetime of the
optical transition of the absorbing carbon phase. These parameters are deduced from the imaginary
part of the dielectric function using Tauc-Lorentz model (TL) and from the extinction coefficient
using Forouhi-Bloomer model (FB) in which an energy dependence of the matrix element of the
transition has been introduced. Furthermore, the energies of the peak transition and the maximum
of the extinction coefficient are so similar that they prove the self-consistency of the modified-FB
model applied to the amorphous carbon phase of the composite films
Population-induced nonlinear optical properties near the E1 and E1 + Delta1 critical points in Ge quantum dots
No full textEllipsometric study of optical properties of liquid Ga nanoparticles
No full textThe 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
Thermodynamic Properties and Optical Characterization of Metal Nanoparticles in Dielectric Matrix
No full text
Fundamental properties of lead and tin metal nanocrystals in a dielectric matrix
No full textA careful inspection of the temperature evolution of Pb and Sn nanoparticles encased in a SiOx(x,1) matrix was carried out by means of optical reflectivity and dark field electron microscopy measurements. A strong decrease of the melting temperature with size and the presence of an hysteresis cycle, which clearly separates melting and solidification temperatures, are evidenced. It is shown that an appreciable tailoring of the properties of the effective medium can be obtained
Quantum confinement effects above the band gap in Ge quantum dots
No full textedited by M. Scheffler and R. Zimmermann, World Scientific Publishing, Singapore, 199
Brewster angle technique to study metal nanoparticle distributions in dielectric matrix
No full textWe 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
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