Picosecond third-order nonlinearities in metal-complexed PDA's and all-optical switching potentiality in Fabry-Perot devices containing poly-DCHD

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A facile method to prepare hexagonal molybdenum trioxide microrods

We report the successfully preparation of straight and well faceted hexagonal - MoO 3 rods by a simple method consisting o f a thermal treatment at low temperature applied to molybdenum diluited in a mixture of HCl and HNO 3. We have obtained sub-micrometer hexagonal rods several microns long with defect free walls. Electron scanning microscopy (SEM) and microRaman spectroscopy w ere used to characterize the obtained rods. ur results demonstrate the feasibility of synthesizing h-MoO 3 in a very simple way

Preparation of zinc peroxide nanoparticles by laser ablation of solid in liquids

In the last decade, there has been interest on the synthesis and characterization of Zinc peroxide (ZnO2) due to its potential applications as biocide, bactericide, inorganic oxidant and so on. ZnO2 can be obtained as a powder with a cubic structure and has been utilized as a precursor to obtain Zinc oxide (ZnO). ZnO2 can be considered as an oxygen reservoir since when it is heated at relatively low temperatures oxygen is released. Various approaches have been utilized to synthetize ZnO2 powders like sol-gel, organometallic precursors, hydrothermal, Laser Ablation of Solids in Liquids (LASL), and so on. While the hydrothermal route is one of the most utilized methods to obtain ZnO2, the LASL technique has only been utilized by the Gondal´s group to synthesize zinc peroxide nanoparticles. Escobedo et al. have been reported a study of the vibrational properties of ZnO2 NPs synthesized by the hydrothermal method. Additionally, they present results of XRD, TEM and by thermal analysis determine the decomposition temperature of their ZnO2 NPs. Recently, the Escobedo-Morales’s group has reported a green method to prepare ZnO nanostructures employing as starting material ZnO2 (prepared by hydrothermal method

Preparation of quantum dots hydrogel nanocomposites with improved cytotoxicity

Nanocomposites are materials with unique properties and a wide range of applications. The combination of different nanostructures with traditional materials gives a variety of possibilities that should be analyzed. Especially, functional fluorescent semiconductor quantum dots (QDs) embedded in polymeric matrices have shown promising fluorescence and biocompatibility properties. These hybrid materials can be used in medical applications such as biodiagnostic and bioimaging. In this study, two hydrogels, one of polyethylene glycol diacrylate (PEGDA) and other of polyacrylamide (PAAm), were prepared with quantum dots of CdTe (4 nm of diameter) and characterized. The aim of this research was to analyze the optical properties of the nanocomposites and their cell viability. QDs nanocomposites were fabricated by a free radical polymerization process. The optical studies showed that the nanocomposites have well defined properties of fluorescence. To study the biocompatibility of the nanocomposites, metastatic B16f10 cell line were used and MTT assay was performed. The nanocomposites had a significant improved cell viability compared with QDs solutions

Quantification of phase content in TiO2 thin films by Raman spectroscopy

Recently, it has been reported that TiO2 with mixture of phases (anatase/rutile) exhibit higher photocatalytic activity than TiO2 with pure anatase phase. Therefore, the production and correct quantification of the ratio of phases becomes an important task. In this work, anatase TiO2 thin films were obtained by the DC reactive magnetron sputtering technique. TiO2 with mixture of phases (anatase/rutile) were prepared by thermal annealing of the as-deposited thin films. The value of the anatase/rutile ratio in the titanium dioxide thin films was estimated using Raman spectroscopy. Additionally, it is reported the dependence of the bandgap of the TiO2 thin films as a function of the anatase/rutile ratio. The band gap of the TiO2 thin films was determined from diffuse reflectance measurements

Characterization of nanostructured SnO2 films deposited by reactive DC-magnetron sputtering

Nanostructured tin oxide thin films were deposited on silicon and glass slides substrates by reactive DC-Magnetron sputtering using a tin target in a mixture of argon and oxygen gases. The substrate temperature was varied in the range from 53 to 243 oC, keeping the other deposition parameters constant. The tin oxide films were characterized by: Scanning Electron Microscopy, Energy Dispersive Spectrometry, X Ray Diffraction, microRaman spectroscopy and UV-VIS spectroscopy. It was found that the substrate temperature has an effect mainly on the structural, morphological and optical properties of the thin films. At 53 and 90 oC the tetragonal crystalline phase was obtained while a mixture of crystalline phases (o-SnO2 and t-SnO2) was obtained at 148, 185 and 243 oC

Laser ablated carbon nanodots for light emission

The synthesis of fluorescent carbon dots-like nanostructures (CNDs) obtained through the laser ablation of a carbon solid target in liquid environment is reported. The ablation process was induced in acetone with laser pulses of 1064, 532, and 355 nm under different irradiation times. Close-spherical amorphous CNDs with sizes between 5 and 20 nm, whose abundance strongly depends on the ablation parameters were investigated using electron microscopy and was confirmed using absorption and emission spectroscopies. The π- π* electronic transition at 3. 76 eV dominates the absorption for all the CNDs species synthesized under different irradiation conditions. The light emission is most efficient due to excitation at 3.54 eV with the photoluminescence intensity centered at 3. 23 eV. The light emission from the CNDs is most efficient due to ablation at 355 nm. The emission wavelength of the CNDs can be tuned from the near-UV to the green wavelength region by controlling the ablation time and modifying the ablation and excitation laser wavelength