Photoluminescence property of Ba(Zr0.25Ti0.75)O-3 powders prepared by solid state reaction and polymeric precursor method

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Luminescence properties of Eu(3+)- and Mg(2+)-doped LiTaO(3) obtained via the polymeric precursor method

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Photoluminescence in the CaXSr1-xWO4 system at room temperature

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

BaMoO(4) powders processed in domestic microwave-hydrothermal: Synthesis, characterization and photoluminescence at room temperature

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Strong infrared spectral broadening in low-loss As-S chalcogenide suspended core microstructured optical fibers

We report the fabrication and characterization of the first guiding chalcogenide As(2)S(3) microstructured optical fibers (MOFs) with a suspended core. At 1.55 mu m, the measured losses are approximately 0.7 dB/m or 0.35 dB/m according to the MOF core size. The fibers have been designed to present a zero dispersion wavelength (ZDW) around 2 mu m. By pumping the fibers at 1.55 mu m, strong spectral broadenings are obtained in both 1.8 and 45-m-long fibers by using a picosecond fiber laser. (C) 2010 Optical Society of America

Band edge states of the < n >=0 gap of Fibonacci photonic lattices

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

An evaluation of ocean color model estimates of marine primary productivity in coastal and pelagic regions across the globe

Nearly half of the earth's photosynthetically fixed carbon derives from the oceans. To determine global and region specific rates, we rely on models that estimate marine net primary productivity (NPP) thus it is essential that these models are evaluated to determine their accuracy. Here we assessed the skill of 21 ocean color models by comparing their estimates of depth-integrated NPP to 1156 in situ C-14 measurements encompassing ten marine regions including the Sargasso Sea, pelagic North Atlantic, coastal Northeast Atlantic, Black Sea, Mediterranean Sea, Arabian Sea, subtropical North Pacific, Ross Sea, West Antarctic Peninsula, and the Antarctic Polar Frontal Zone. Average model skill, as determined by root-mean square difference calculations, was lowest in the Black and Mediterranean Seas, highest in the pelagic North Atlantic and the Antarctic Polar Frontal Zone, and intermediate in the other six regions. The maximum fraction of model skill that may be attributable to uncertainties in both the input variables and in situ NPP measurements was nearly 72%. on average, the simplest depth/wavelength integrated models performed no worse than the more complex depth/wavelength resolved models. Ocean color models were not highly challenged in extreme conditions of surface chlorophyll-a and sea surface temperature, nor in high-nitrate low-chlorophyll waters. Water column depth was the primary influence on ocean color model performance such that average skill was significantly higher at depths greater than 250 m, suggesting that ocean color models are more challenged in Case-2 waters (coastal) than in Case-1 (pelagic) waters. Given that in situ chlorophyll-a data was used as input data, algorithm improvement is required to eliminate the poor performance of ocean color NPP models in Case-2 waters that are close to coastlines. Finally, ocean color chlorophyll-a algorithms are challenged by optically complex Case-2 waters, thus using satellite-derived chlorophyll-a to estimate NPP in coastal areas would likely further reduce the skill of ocean color models.

Morphology and Photoluminescence of HfO2 Obtained by Microwave-Hydrothermal

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Design, construction, and performance of a real-time holographic refractometry prototype for liquid analysis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Suppression of Anderson localization of light in one-dimensional disordered photonic superlattices

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Simple and versatile heterodyne whole-field interferometer for phase optics characterization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Hydrothermal surface-wave instability and the Kuramoto-Sivashinsky equation

We consider a system formed by an infinite viscous liquid layer with a constant horizontal temperature gradient and a basic nonlinear bulk velocity profile. In the limit of long wavelength and large nondimensional surface tension we show that hydrothermal surface-wave instabilities may give rise to disturbances governed by the Kuramoto-Sivashinsky equation. A possible connection to hot-wire experiments is also discussed. © 1994.

Pre-resonant Raman effect of CrO2- 4 in a metasilicate glass

Pre-resonant Raman effect of chromate ion, CrO2- 4, was observed in a metasilicate glass with molar composition 2Na2O · 1CaO · 3SiO2 containing 1.0 wt% of Cr2O3. Raman spectra were measured by the conventional 90° scattering geometry and by the microprobe Raman spectroscopic techniques. The presence of chromate ions in the glass is favoured by the glass composition and oxidizing conditions during the glass melting, and they are responsible for optical absorption bands at 370 and 250 nm. Raman spectrum of the undoped glass presents bands at 625, 860 and 980 cm-1, and the presence of chromate ions gives rise to additional bands at 365, 850 and a shoulder at 890 cm-1. An enhancement of the 850 cm-1 Raman band is observed with decreasing laser exciting wavelength. The exciting frequency dependence of the intensity of this band is discussed in terms of theoretical models given in the literature.

Optical properties of chromium-doped fluoroindate glasses

This work reports on the optical properties of Cr3+ ions in the pseudoternary system InF3-GdF3-GaF3. Linear properties, investigated through absorption and emission spectra, provide information on the crystal field, the frequency, and number of phonons emitted during the absorption to the 4T2 band and the emission to the 4A2 ground state, and the Fano antiresonance line shape in the vicinity of the 4A2→2E transition. A study of the nonlinear refractive index as a function of the wavelength, carried out with the Z-scan technique, provides spectroscopic data about electronic transitions starting from the excited state.

Polishable and Renewable DNA Hybridization Biosensors

Routine applications of DNA hybridization biosensors are often restricted by the need for regenerating the single-stranded (ss) probe for subsequent reuse. This note reports on a viable alternative to prolonged thermal or chemical regeneration schemes through the mechanical polishing of oligonucleotide-bulk-modified carbon composite electrodes. The surface of these biocomposite hybridization biosensors can be renewed rapidly and reproducibly by a simple extrusion/polishing protocol. The immobilized probe retains its hybridization activity on confinement in the interior of the carbon paste matrix, with the use of fresh surfaces erasing memory effects and restoring the original target response, to allow numerous hybridization/measurement cycles. We expect that such reusable nucleic acid modified composite electrodes can be designed for a wide variety of biosensing applications.