Photoconductive and third-order nonlinear optical properties exhibited by Cu2ZnSnS4 nanostructures are presented. The samples were synthetized in thin film form by a spray pyrolysis processing route. ...Distinctions in the photoconductive behavior throughout the samples were clearly noted by modulating their optoelectronic response dependent on electrical frequency. Vectorial two-wave mixing experiments were carried out at a 532 nm wavelength provided by a Nd:YAG laser system to study the optical nonlinearities in the samples. An induced transparency effect was observed during nanosecond single-beam experiments in the nanostructures reported. Quantum and thermal processes were considered to be the main physical mechanism responsible for the photo-electrical phenomena and nonlinear refraction in the nanostructures. Potential applications for developing nanophotonic and nanoelectronic instrumentation systems can be contemplated.
Removal of hexavalent chromium was accomplished by using photocatalyst materials of TiO
doped with tungsten oxide, environmental air as oxygen supply and white light as irradiation source. Dichromate ...anions in concentration ranges of 50 to 1000 μg/L were removed by means of aqueous dispersions of TiO
doped with tungsten. The aqueous chromium analyses were performed by Differential Pulse Voltammetry technique. Additionally, mineralization of CO
gas was promoted by the photocatalysis process, as was clearly shown by Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS) analyses obtained from the TiO
samples recovered after photocatalytic experiments. Results of sample analyses by Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM) are presented and discussed.
•Dichromate anions in concentration ranges of 50–1000 μg/L were removed by means of aqueous dispersions of TiO2 doped with tungsten.•The best results for Cr (VI) removal were obtained with pH values ...from 2 to 4.•The CO2 contained in the ambiental air that had been injected into the photocatalytic reactor for the chromium removal experiments was captured by the photocatalyst.
Removal of hexavalent chromium was accomplished by using photocatalyst materials of TiO2 doped with tungsten oxide, environmental air as oxygen supply and white light as irradiation source. Dichromate anions in concentration ranges of 50 to 1000 μg/L were removed by means of aqueous dispersions of TiO2 doped with tungsten. The aqueous chromium analyses were performed by Differential Pulse Voltammetry technique. Additionally, mineralization of CO2 gas was promoted by the photocatalysis process, as was clearly shown by Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS) analyses obtained from the TiO2 samples recovered after photocatalytic experiments. Results of sample analyses by Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM) are presented and discussed.
Nanoscale plasmonic particles represent a crucial transformation on optical and electronic properties exhibited by advanced materials. Herein are reported remarkable interferometric optical effects ...with dependence on polarization for filtering or modulating electronic signals in multilayer nanostructures. Metallic nanoparticles were incorporated in randomly distributed networks of reduced graphene oxide by an in-situ vapor-phase deposition method. The polarization-selectable nonlinear optical absorption contribution on the photoconductivity of reduced graphene oxide decorated with gold nanoparticles was analyzed. Nanosecond pulses at 532 nm wavelength were employed in a two-wave mixing experiment to study photoconduction and nonlinear optical absorption in this nanohybrid material. The ablation threshold of the sample was measured in 0.4 J/cm
. Electrochemical impedance spectroscopy measurements revealed a capacitive response that can be enhanced by gold decoration in carbon nanostructures. A strong two-photon absorption process characterized by 5 × 10
m/W was identified as a physical mechanism responsible for the nonlinear photoconductive behavior of the nanostructures. Experimental shift of 1 MHz for the cutoff frequency associated with an electrical filter function performed by the sample in film form was demonstrated. Moreover, amplitude modulation of electronic signals controlled by the polarization of a two-wave mixing experiment was proposed. All-optical and optoelectronic nanosystems controlled by multi-photonic interactions in carbon-based materials were discussed. The key role of the vectorial nature of light in two-wave mixing experiments is a fascinating tool for the exploration of low-dimensional systems.
The impact of vectorial magnetic field effects on electrical conductivity and nonlinear optical transmittance exhibited by multi-wall carbon nanotubes was studied. The samples were synthetized by an ...aerosol pyrolysis processing route in a thin film form. Optical signals in a two-wave mixing configuration allowed us to identify two orthogonal directions of propagation for a magnetic field travelling through the nanomaterials studied. A selective modification in optical absorption was considered to be induced by magnetic perturbations in the sample. Standard optical Kerr gate measurements were carried out for exploring the third order nonlinear optical behavior of the film. A capacitive effect influenced by optical and magnetic excitations was distinguished to be characteristic of the sample. Magneto-quantum conductivity sensitive to the direction of an external magnetic field interacting with the tubes was analyzed. Magnetically-induced changes in electronic band parameters seem to be the main responsible for the optical and electrical modulation observed in the nanostructures. Immediate applications for developing magneto-optical and magneto-electrical functions can be contemplated.
•Nickel oxide decorated carbon nanotubes were prepared by chemical vapor deposition.•Contrast in photoconductivity phenomena in the nanohybrid was analyzed.•Electrical and nonlinear optical ...properties were evaluated.•A Wheatstone bridge sensor based metal/carbon nanostructures was proposed.
Within this work was explored the influence of nickel oxide decoration on the photoconductive effects exhibited by multiwall carbon nanotubes. Samples in thin film form were prepared by a chemical vapor deposition method. Experiments for evaluating the photo-response of the nanomaterials at 532 nanometers wavelength were undertaken. A contrasting behavior in the photoelectrical characteristics of the decorated nanostructures was analyzed. The decoration technique allowed us to control a decrease in photoconduction of the sample from approximately 100μmhos/cm to −600μmhos/cm. Two-wave mixing experiments confirmed an enhancement in nanosecond nonlinearities derived by nickel oxide contributions. It was considered that metallic nanoparticles present a strong responsibility for the evolution of the optoelectronic phenomena in metal/carbon nanohybrids. Impedance spectroscopy explorations indicated that a capacitive behavior correspond to the samples. A potential development of high-sensitive Wheatstone bridge sensors based on the optoelectrical performance of the studied samples was proposed.
•A nanostructured double-stage switching system was proposed.•Magneto-optical effects and nonlinear optics were analyzed.•Strong magneto-optical properties in carbon nanotubes were evaluated.•Au ...nanoparticles in an optical Kerr gate were proposed.
Herein is addresses the application of attractive and large magnetization of carbon nanotubes for modulating optical signals. A cascade system based on multiwall carbon nanotubes in thin film form and Au nanoparticles embedded in a TiO2 thin solid film were combined to achieve a nonlinear magneto-optical switching action. An all-optical switching device rising from an optical Kerr effect in the second stage is proposed to transmit a magneto-optical signal from the first stage. Multiwall carbon nanotubes with large magnetic sensitivity were incorporated in the arm of a Michelson interferometer to promote a change in the refractive index due to the Aharonov-Bohm effect. The Michelson interferometer was monitoring magneto-optical processes by a 532 nm wavelength. The second stage was recorded with a 532 nm nanosecond two-wave mixing configuration testing Au nanoparticles embedded in a TiO2 thin film. The development of simultaneous all-optical and magneto-optical systems is attractive since multifunctional quantum operations can be contemplated to be performed in low-dimensional platforms. In this paper is proposed a switching device that exploits interferometry for detecting magnetic signals and optical Kerr gating with the advantages of distinct nanostructures.
•Rotating effects and their influence on optical nonlinearities are presented.•A mechano-optical XOR logic function is proposed.•Nanosecond self-diffraction was analyzed by a two-wave mixing.•Au-Pt ...nanoparticles embedded in a rotating TiO2 thin solid film were studied.
Mechano-optical rotating effects and their influence on the nonlinear optical properties exhibited by Au-Pt nanoparticles in a TiO2 thin solid film were analyzed. The plasmonic nanoparticles were prepared by a sol-gel processing route that involves TiO2 decoration. A vectorial two-wave mixing method with self-diffraction allowed us describing the third-order nonlinear optical response exhibited by a rotating sample during a polarization-resolved irradiation. A strong modification in the induced birefringence originated at 532 nm wavelength with nanosecond pulses was identified when the sample presents rotating motion. The absence of nonlinearity in the transmittance of a single-beam revealed that the optical Kerr effect in the nanostructures corresponds to the main mechanism responsible for the studied third-order nonlinear optical behavior. It was identified that the rotation of the sample can modulate self-diffraction signals in a two-wave mixing. An exclusive-or logic gate function was proposed by using a two-wave mixing configuration assisted by mechanical rotation of the sample. Potential applications of this technique can be contemplated for processing optical signals or quantum phenomena by combinational mechano-optical circuits.
The modification in the third-order nonlinear optical response exhibited by rotating bimetallic Au–Pt nanoparticles in an ethanol solution was analyzed. The samples were prepared by a sol–gel ...processing route. The anisotropy associated to the elemental composition of the nanoparticles was confirmed by high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy measurements. The size of the nanoparticles varies in the range from 9 to 13 nm, with an average size of 11 nm. Changes in the spatial orientation of the nanomaterials automatically generated a variation in their plasmonic response evaluated by UV–Vis spectroscopy. A two-wave mixing experiment was conducted to explore an induced birefringence at 532 nm wavelength with nanosecond pulses interacting with the samples. A strong optical Kerr effect was identified to be the main responsible effect for the third-order nonlinear optical phenomenon exhibited by the nanoparticles. It was estimated that the rotation of inhomogeneous nanostructures can provide a remarkable change in the participation of different surface plasmon resonances, if they correspond to multimetallic nanoparticles. Potential applications for developing low-dimensional gyroscopic systems can be contemplated.
Herein are reported nonlinear optical effects and optical spectroscopy studies for identifying particular modifications in blood plasma and cerebroespinal fluids with plasmonic nanoparticles. The ...influence of the explored biofluids on the absorption band related to the Surface Plasmon Resonance exhibited by Gold nanoparticles was analyzed. The Gold nanoparticles were synthetized by a sol-gel method and characterized by Scanning Electronic Microscopy. It was found that the evolution of the plasmonic and third-order nonlinear optical response of the nanoparticles present characteristic signatures that can be related to interparticle effects and flow velocity in biofluids. It was demonstrated a dynamic and nonlinear optical behavior exhibited by the nanoparticles with higher sensitivity than spectroscopic measurements for detecting healthy and unhealthy human fluids related to particular medical diagnosis of donors. We highlighted the impact of these results for opening the possibility for engineering advanced nanomedicine vehicles with potential applications in delivery, tracking and therapy by the assistance of plasmonic nanoparticles interacting with biological media. Advantages exhibited by ultrafast two-wave mixing experiments for diagnostic functions and nanomedicine applications in nanofluids can be contemplated.
•Characteristic optical signatures of blood plasma and cerebroespinal fluids was studied.•The plasmonic response of metallic nanoparticles was analyzed.•Nonlinear optical behavior of the nanoparticles can be used as biosensors.•Nanovehicles by the assistance of plasmonic nanoparticles can be contemplated.
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