Spectroscopic ellipsometry and polarimetry for materials and systems analysis at the nanometer scale: state-of-the-art, potential, and perspectives

This paper discusses the fundamentals, applications, potential, limitations, and future perspectives of polarized light reflection techniques for the characterization of materials and related systems and devices at the nanoscale. These techniques include spectroscopic ellipsometry, polarimetry, and reflectance anisotropy. We give an overview of the various ellipsometry strategies for the measurement and analysis of nanometric films, metal nanoparticles and nanowires, semiconductor nanocrystals, and submicron periodic structures. We show that ellipsometry is capable of more than the determination of thickness and optical properties, and it can be exploited to gain information about process control, geometry factors, anisotropy, defects, and quantum confinement effects of nanostructures

Mesoporous silica nanoparticles with tunable pore size for tailored gold nanoparticles

The aim of this paper was to verify a possible correlation between the pore-size of meso- porous silica nanoparticles (MSNs) and the sizes of gold nanoparticles (AuNPs) obtained by an impreg- nation of gold(III) chloride hydrate solution in the MSNs, followed by a specific thermal treatment. Mesoporous silica nanoparticles with tunable pore diameter were synthesized via a surfactant-assisted method. Tetraethoxysilane as silica precursor, cetyl- trimethylammonium bromide (CTAB) as surfactant and toluene as swelling agent were used. By varying the CTAB–toluene molar ratio, the average dimension of the pores could be tuned from 2.8 to 5.5 nm. Successively, thiol groups were grafted on the surface of the MSNs. Finally, the thermal evolution of the gold salt, followed by ‘‘in situ’’ X-ray powder diffraction (XRPD) and thermogravimetric analysis (TGA), revealed an evident correlation among the degradation of the thiol groups, the pore dimension of the MSNs and the size of the AuNPs. The samples were characterized by means of nitrogen adsorption– desorption, transmission electron microscopy, small- angle X-ray scattering, XRPD ‘‘in situ’’ by synchro- tron radiation, and ‘‘ex situ’’ by conventional tech- niques, diffuse reflectance infrared Fourier transform spectroscopy, and TGA

Size-Dependent Optical Properties of Metallic Nanostructures

Metallic nanostructures are a key component of current and future nanotechnology devices since their individual properties convey the appropriate characteristics for applications in several fields of science and technology. At the nanoscale size, optical properties of metal structures depend not only on the type of material but also on the dimensions and geometry of the structure, suggesting the possibility of tuning optical resonances through appropriate engineering. In this chapter, we will describe methods for calculation of size-dependent optical properties of metal nanostructures and show the successful use of extinction spectroscopy technique to determine the size of nanoparticles (Nps).Fil: Scaffardi, Lucia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Schinca, Daniel Carlos. No especifíca;Fil: Lester, Marcelo Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Videla, Fabian Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Santillán, Jesica María José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Abraham, Ricardo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; Argentin

Ag nanoparticles formed by femtosecond pulse laser ablation in water: self assembled fractal structures

We report for the first time on the formation of self-assembled fractals of spherical Ag nanoparticles (Nps) fabricated by femtosecond pulse laser ablation of a solid silver target in water. Fractal structures grew both in two and three Euclidean dimensions (d). Ramified-fractal assemblies of 2 nm height and 5–14 μm large, decorated with Ag Nps of 3 nm size, were obtained in a 2d geometry when highly diluted drops of colloidal suspension were dried at a fast heating rate over a mica substrate. When less-diluted drops were dried at slow heating rate, isolated single Nps or rosette-like structures were formed. Fractal aggregates about 31 nm size in 3d geometry were observed in the as-prepared colloidal suspension. Electron diffraction and optical extinction spectroscopy (OES) analyses performed on the samples confirmed the presence of Ag and Ag2O. The analysis of the optical extinction spectrum, using the electrostatic approximation of Mie theory for small spheres, showed the existence of Ag bare core, Ag–Ag2O and air–Ag core–shell Nps, Ag–Ag2O being the most frequent type [69 % relative abundance (r.a.)]. Core-size and shell-thickness distribution was derived from OES. In situ scattering measurements of the Ag colloidal suspension, carried out by small-angle X-ray scattering, indicate a mass fractal composed of packaged 〈DSAXS〉 = (5 ± 1) nm particles and fractal dimension df = 2.5. Ex situ atomic force microscopy imaging displayed well-ramified structures, which, analyzed with box-counting method, yield a fractal dimension df = 1.67. The growing behavior of these 2d and 3d self-assembled fractals is consistent with the diffusion-limited aggregation model.Fil: Santillán, Jesica María José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones Opticas (i); Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; ArgentinaFil: Fernandez Van Raap, Marcela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Física La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Departamento de Física; ArgentinaFil: Mendoza Zélis, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ingenieria; ArgentinaFil: Coral, Diego Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Física La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Departamento de Física; ArgentinaFil: Muraca, Diego. Universidade Estadual de Campinas; BrasilFil: Schinca, Daniel Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones Opticas (i); Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de La Plata. Facultad de Ingenieria; ArgentinaFil: Scaffardi, Lucia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones Opticas (i); Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional de La Plata. Facultad de Ingenieria; Argentin

Controlled insulator-to-metal transformation in printable polymer composites with nanometal clusters

10.1038/nmat1806Nature Materials62149-15