Plasmonic resonances in hybrid systems of aluminum nanostructured arrays and few layer graphene within the UV-IR spectral range.

The size-controllable and ordered Al nanocavities and nanodomes arrays were synthesized by electrochemical anodization of aluminum using phosphoric acid, citric acid and mixture both acids. Few layer graphene (FLG) was transferred directly on top of Al nanostructures and their morphology were evaluated by scanning electron microscopy. The interaction between FLG and the plasmonic properties of Al nanostructures arrays were investigated based on specular reflectivity in the ultraviolet-visible-infrared range and Raman spectroscopy. We found that their optical reflectivity was dramatically reduced as compared with unstructured Al. At the same time pronounced reflectivity dips were detectable in the 200-896 nm wavelength range, which were ascribed to plasmonic resonances. The plasmonic properties of these nanostructures do not exhibit evident changes by the presence of FLG in the UV-vis range of the electromagnetic spectrum. By contrast, the surface-enhanced Raman spectroscopy of FLG was observed in nanocavities and nanodomes structures that result in an intensity increase of the characteristic G and 2D bands of FLG induced by the plasmonic properties of Al nanostructures.

Silicalite-1, an adsorbent for 2-, 3-, and 4-chlorophenols.

The adsorption of the three chlorophenol isomers, ortho, meta and para, by silicalite-1 has been studied at 30 °C, below the solubility (at the same temperature) in water. Large differences, up to 30 times, have been observed between the adsorption of the para- vs. the ortho-isomer. The difference of behavior observed between the isomers is assigned to the tendency to self-organization of the para-isomer. It seems probable that the adsorption sites are at the intersection channels. From a technical point of view, silicalite-1 seems a competitive adsorbent for p-chlorophenol.

Application of principal component analysis and Raman spectroscopy in the analysis of polycrystalline BaTiO3 at high pressure.

The principal component analysis (PCA) was applied to Raman spectra of polycrystalline BaTiO(3) under pressure from atmospheric pressure to approximately 6.72 GPa. For the system utilized, PCA was able to distinguish spectral features and to determine the phase transition pressure: tetragonal to cubic at approximately 2.0 GPa. The present study demonstrates the potentialities of the application of PCA to the investigation on phase transitions at high pressure by Raman spectroscopy.

Contact angle studies on anodic porous alumina.

The preparation of nanostructures using porous anodic aluminum oxide (AAO) as templates involves the introduction of dissolved materials into the pores of the membranes; one way to determine which materials are preferred to fill the pores involves the measurement of the contact angles (theta) of different solvents or test liquids on the AAOs. Thus, we present measurements of contact angles of nine solvents on four different AAO sheets by tensiometric and goniometric methods. From the solvents tested, we found dimethyl sulfoxide (DMSO) and N,N(')-dimethylformamide (DMF) to interact with the AAOs, the polarity of the solvents and the surfaces being the driving force.

A magnonic gas sensor based on magnetic nanoparticles.

In this paper, we propose an innovative, simple and inexpensive gas sensor based on the variation in the magnetic properties of nanoparticles due to their interaction with gases. To measure the nanoparticle response a magnetostatic spin wave (MSW) tunable oscillator has been developed using an yttrium iron garnet (YIG) epitaxial thin film as a delay line (DL). The sensor has been prepared by coating a uniform layer of CuFe2O4 nanoparticles on the YIG film. The unperturbed frequency of the oscillator is determined by a bias magnetic field, which is applied parallel to the YIG film and perpendicularly to the wave propagation direction. In this device, the total bias magnetic field is the superposition of the field of a permanent magnet and the field associated with the layer of magnetic nanoparticles. The perturbation produced in the magnetic properties of the nanoparticle layer due to its interaction with gases induces a frequency shift in the oscillator, allowing the detection of low concentrations of gases. In order to demonstrate the ability of the sensor to detect gases, it has been tested with organic volatile compounds (VOCs) which have harmful effects on human health, such as dimethylformamide, isopropanol and ethanol, or the aromatic hydrocarbons like benzene, toluene and xylene more commonly known by its abbreviation (BTX). All of these were detected with high sensitivity, short response time, and good reproducibility.