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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Third Harmonic Generation of Azo-Based Thin Films
摘要： This paper presents investigation results of the linear and nonlinear optical properties for thin films containing azo-based compounds. Thin films were deposited on a glass substrate using spin coating technique. The linear optical properties were examined by using Absorption method. The nonlinear optical properties as well as Third Harmonic Generation were examined by means of Maker fringe technique by exploiting Nd:YAG laser at a wavelength 1064 nm. Third-order nonlinear optical susceptibility were calculated using theoretical model.
关键词： third harmonic generation,azo-based compounds,nonlinear optical response,thin film,nonlinear susceptibility
更新于2025-09-10 09:29:36
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Impact of ligand rotation: Synthesis, crystal structures and third-order nonlinear optical properties of Mn(II), Cu(II) and Ni(II) complexes with 5?diethylamino?2?((4?(phenyldiazenyl) phenylimino) methyl) phenol
摘要： Three new coordination compounds containing 5?diethylamino?2?((4?(phenyldiazenyl) phenylimino) methyl) phenol ligand have been synthesized and fully characterized. Single crystal structure showed that the ligand shows multiple coordination mode and the phenyl group next to azo group could rotate during the coordination process. In Mn (HDAPPP)2Cl2·CH3CN (1), the HDAPPP behaved as a mono ligand because of the N of the imine group is protonated in the keto form and does not participate in coordination. While the Cu(DAPPP)2 (2) and Ni(DAPPP)2 (3) are classic complexes containing azo-Schiff base ligand. The fluorescence emission peaks of compounds indicated that the fluorescence of the compounds are mainly derived from the π-π* charge transition of the ligand and affected by the rotation of ligand. The UV–Vis data revealed that the compound 1–3 with the maximum absorption peak at 425 nm, 440 nm and 338 nm, respectively. This clearly confirmed that the compound 1 is mainly based on the keto configuration while the compound 3 is mainly based on the enol configuration. Z-scan experiments showed that all compounds exhibited reverse saturable absorption effect and self-defocusing effect for nonlinear optical materials. The nonlinear absorption coefficients (β) of compound 1–3 are evaluated to be 6 × 10?11 m·W?1, 4.4 × 10?11 m·W?1, and 1.7 × 10?11 m·W?1 respectively, and the nonlinear refraction coefficients (n2) are ?1.4 × 10?17 m2·W?1, ?1.6 × 10?17 m2·W?1, ?7.0 × 10?18 m2·W?1 respectively. The nonlinear optical property of compound 1 and 2 are better than compound 3, which are influenced by ligand rotation after coordination.
关键词： Azo-Schiff base ligand,Rotation,Third-order nonlinear optical,Schiff base complex
更新于2025-09-10 09:29:36
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ZnO nanospheres based simple hydrothermal route for photocatalytic degradation of azo dye
摘要： This novel work presents a promising application to use Zinc oxide nanospheres as nanocatalysts in photocatalytic degradation of methyl orange dye. The hydrothermal route was utilized in the synthesis process of ZnO nanospheres. The size of the synthesized ZnO nanoparticles is around 200-250 nm diameter. The synthesized nano-oxides were characterized utilizing several instruments such as X-ray diffraction, Brunauer, Emmett, and Teller (BET), and scanning electron microscope (SEM). The resulting nanoparticles are utilized as an efficient tool for degradation of methyl orange (MO) dye under UV radiation. Essential parameters were studied on degradation process involving the initial concentration of MO, pH, stirring the solution, dose of the ZnO nanospheres, the oxygen content of the solution, calcination of the nanomaterials. All activity experiments under UV radiation provide excellent results for the degradation process of MO. Also, the recovery of ZnO nanomaterials was investigated based on the photocatalytic process efficiency. The results show the high possibility of reuse ZnO nanospheres for several photocatalytic processes. Also, the nanocatalysts were applied for a real environmental sample with providing high photocatalytic performance.
关键词： methyl orange,ZnO nanospheres,photocatalytic degradation,hydrothermal method,azo dyes
更新于2025-09-10 09:29:36
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Surface relief gratings in azo-polymers revisited
摘要： We use the concept of vectorial photochemical tweezing to rationalize the experimental observations of surface relief gratings in azo-polymers, e.g., the photochemically induced motion of the polymer in a one-dimensional intensity gradient produced by two-laser beam interference. Vectorial motion of matter occurs when photochemically active, polarization sensitive molecules are photo-selected in a gradient of light intensity. Directional motion is imposed parallel to the gradient vector with an efficiency that depends on the respective orientations of the vectors of light polarization and intensity gradient. Different combinations of polarizations of the interfering beams leading to differing efficiencies of matter motion are revisited and discussed. We show that the magnitude of photoisomerization force dictates the efficiency of the observed matter motion. We also show that the spatial distribution of the photo-moved matter is Gaussian, the height and width of which exhibit an intensity dependence which is predicted by the theory of photochemical vectorial tweezing; both theory and experiments indicate that the photoisomerization force, which acts on thin films of azo-polymers, is in the mN range.
关键词： photoisomerization force,vectorial motion,photochemical tweezing,azo-polymers,surface relief gratings
更新于2025-09-09 09:28:46
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The effect of the length of terminal n-alkyl carboxylate chain on self-assembling and photosensitive properties of chiral lactic acid derivatives
摘要： A new series of photosensitive azo materials possessing a chiral alkyl lactate moiety and terminal n-alkyl carboxylate unit close to the azo group has been synthesised and studied. The length of the n-alkyl carboxylate chain has been systematically varied in order to establish the effect of the molecular structure on the self-assembling behaviour. Two series of materials possessing hexyl and dodecyl alkyl chains in the chiral part of the molecule have been studied. It has been shown that the length of both the alkyl chains strongly influences the mesomorphic behaviour, however, each chiral/achiral chain has different utility to tune the mesomorphic properties. With exception of the compound with the longest chains, all studied compounds exhibited the chiral tilted ferroelectric smectic C* phase. Based on the combination of terminal alkyl chains, chiral nematic, orthogonal smectic A*, and twist grain boundary smectic A* phases have been detected on cooling beyond the SmC* phase. The presence of the photosensitive functional N=N group in the molecular core allowed further tuning of the material properties by UV light illumination. The E-to-Z photoisomerization of the azo group and subsequent thermal back-isomerisation have been studied in solution by nuclear magnetic resonance and most importantly in the mesophases on bulk samples. We report on UV-induced isothermal switching from chiral smectic and nematic mesophases directly into the isotropic phase, respectively, and differences in the textures of mesophase upon restoration of the ordered liquid.
关键词： E-Z isomerisation,ferroelectric phase,photosensitive liquid crystals,azo group,chiral liquid crystals,NMR spectroscopy,optical switches
更新于2025-09-09 09:28:46
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Halloysite based nanocomposites and photocatalysis: A Review
摘要： Heterogeneous photocatalysis is an e?cient, relatively cheap and environmentally friendly technology for decomposing various organic and air pollutants. Halloysite is a natural clay mineral usually in the form of nanotubes that has many applications as well as potential uses including photocatalysis. In this paper the photocatalytic activities of halloysite-based nanocomposites in combination with various photocatalysts that have been synthesized and tested in decomposing organic and air pollutants are reviewed. Many photocatalysts have been synthesized and among them TiO2 in the form of anatase, or rutile, or a mixture of both is the most common photocatalyst due to its e?ectiveness and low cost. Researches by many investigators are summarized and discussed. The possibilities and limitations of halloysite-based nanocomposites for future applications are also discussed and new ?elds of research are proposed. It is suggested that Halloysite-based nanocomposites are more promising in positively charged organic substrates like tetracycline and Rhodamine B where the organic pollutant is attracted by halloysite's negatively charged external surfaces close to the photocatalysts, than neutral like paracetamol or negatively charged which that attraction does not occur.
关键词： Azo dyes,Halloysite nanocomposite,Halloysite,TiO2,VOCs,Heterogeneous catalysis,Air pollutants,Photocatalysis
更新于2025-09-09 09:28:46
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AZO (ZnO:Al) Transparent Conductive Film Prepared by Plasma Enhanced Chemical Vapour Deposition and its Performances in Comparison with ZnO Film
摘要： In this paper, AZO(ZnO:Al) polycrystalline thin films have been fabricated by PECVD (plasma enhanced chemical vapour deposition) method. Based on PECVD method, the fabrication process of AZO film is shown in detail. Furthermore, the measurements of the film electro-optical properties have been bringing forth, in comparison with ZnO film. The results suggested that based on PECVD method, AZO films with strong adhesion to the substrate, as low as 89 ?/% of square resistance and as high as 85 % of visible light transmittance have been deposited on the glass substrate and the silicon substrate, respectively.
关键词： Transparent conductive film,Plasma enhanced chemical vapour deposition,AZO (ZnO:Al)
更新于2025-09-09 09:28:46
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Improved Gas Sensing Performance of ALD AZO 3-D Coated ZnO Nanorods
摘要： This paper reports an enhancement on the sensing performance of ZnO nanorod ethanol sensors with a new approach by utilizing nested coatings of Aluminum doped ZnO (AZO) thin films by Atomic Layer Deposition (ALD) technology. ZnO nanorods were grown by the hydrothermal method with the ZnO seed layer synthesized on Silicon wafers by ALD. To enhance the sensing performance of ZnO nanorod ethanol sensors, multiple coated AZO thin film 3-D coatings were deposited on the surface of the intrinsic ZnO nanorods by ALD. To investigate the sensing performance of the ZnO nanorods sensor for the detection of ethanol vapor, a gas sensor testing system was designed and built with a sealed reaction chamber and a temperature controller. The demonstrated sensing performance results include the sensing response comparison between ZnO nanorods before and after ALD coatings with AZO films at different temperatures and with various concentrations of input ethanol vapor. The response times and recovery times of ZnO nanorods before and after ALD coatings with AZO thin films were analyzed to investigate the sensing enhancement. The sensing response improvement peaks at 25?C room temperature with approximately 200% enhancement. However, the sensing response improvement decreases as a function of increasing operating temperature.
关键词： ZnO nanorods,gas sensor,ethanol vapor,ALD,AZO
更新于2025-09-09 09:28:46
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Effects of Al2O3 buffer layer and annealing on the structural and optoelectronic properties of AZO films
摘要： Transparent conductive aluminum-doped ZnO (AZO) films are deposited on glass substrates using radio frequency (rf) magnetron sputtering, with an AZO ceramic target (Al2O3 content is ~ 3 wt%). Before the AZO films is coated, the hydrophilicity of the surface of the glass substrate is increased by oxygen plasma etching. The grey Taguchi method is used to determine the effect of the deposition parameters on the structural and optoelectronic properties of AZO films. In the confirmation runs, using the grey Taguchi method, an improvement of 46.3% in electrical resistivity and of 1.74% in transmittance is observed. The effect of an Al2O3 buffer layer is also determined. When the thickness of the Al2O3 buffer is increased (from 50 nm to 150 nm), the intensity of the (0 0 2) peak for the AZO films increases and the peaks become sharper, the resistivity of the AZO films is decreased and the transmittance is slightly reduced. Annealing at 500 °C in a vacuum (2.0 Pa) for a period of 30 min, increases the performance of the AZO/Al2O3/glass to better than that for AZO/glass samples. Using a Rockwell-C hardness tester, the AZO/Al2O3 (50 nm)/glass film are classified as HF1, which represents good adhesive mechanical strength. The crystallinity of AZO/Al2O3 (50 nm)/glass samples that are annealed at 500 °C for 30 min is improved, the electrical resistivity is 9.70 × 10?4 ? cm and the optical transmittance in the visible region is approximately 85%. The figure of merit shows that the bi-layer films have better optoelectronic performance.
关键词： optoelectronic properties,AZO films,Al2O3 buffer layer,structural properties,annealing
更新于2025-09-04 15:30:14
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Improvement of the Degradation of Methyl Orange Using a TiO2/BDD Composite Electrode to Promote Electrochemical and Photoelectro-Oxidation Processes
摘要： Electrophoretic deposit of titanium dioxide (TiO2) was carried out over a boron doped diamond plate of 2 cm2, annealing at 350 °C to produce binary TiO2/BDD composite electrode. The composite was characterized by scanning electron microscopy (SEM) and linear sweep voltammetry (LSV) response. N,N-dimethyl-p-nitrosoaniline (RNO) was used as a probe molecule for the detection of free radicals (?OH) during the oxidation of water in phosphate buffer (pH 4) solution; at the TiO2/BDD/hv composite, an apparent first-rate kinetic constant of kobs = 0.1314 min-1 was observed. Afterwards, the composite electrode was applied to degrade 40 and 100 mg L-1 of a typical azo dye methyl orange (MO) via electrochemical process, such as: electro-oxidation (EO) and photoelectro-oxidation (PEO) under 25, 75 and 125 mA cm-2 current density (j); the PEO tests were performed using a UVA lamp at 365 nm. Results showed that the discoloration in the PEO process was larger than in the EO process, 96 and 100 %, respectively. Chemical Oxygen Demand (COD) was tested to evaluate the degradation. Hydroxylated derivatives were identified by means of mass spectroscopy during the PEO of MO in a TiO2/BDD/hv composite electrode.
关键词： TiO2/BDD composite,electrochemical process,hydroxyl radical formation,azo dye,water treatment
更新于2025-09-04 15:30:14