Search results for " solution"
showing 10 items of 3084 documents
Photoelectrochemical study of passive films on stainless steel in neutral solutions
1991
Abstract Passive films formed on AISI 304 stainless steel in neutral solutions are studied using photoelectrochemical technique. Photocurrents were investigated as a function of the wavelength of the incident light, the electrode potential and the time. The results of the measurements together with capacity measurements indicate that the passive film on AISI 304 shows characteristics of a highly doped amorphous or highly disordered n-type semiconductor. The potential dependence of the optical gap values and of the photocurrent transients can be interpreted assuming that the passive film is an iron-chromium oxide solid solution.
Photoelectrical Properties of the SBN Relaxor Ceramics in the Range of the Broad Phase Transition
2014
AbstractA study of the effects of white light on photocurrent kinetics and the low and infra-low frequency relaxation of polarization in the barium-strontium niobate SBN‑75 ceramics is reported. It is found that at a low intensity illumination in the range of the relaxor phase the space charge is mainly responsible for manifestation of photo-electrical properties of SBN-75 ceramics.
Electro- and photo-electrooxidation of 2,4,5-trichlorophenoxiacetic acid (2,4,5-T) in aqueous media with PbO2, Sb-doped SnO2, BDD and TiO2-NTs anodes…
2020
Abstract In this work, the 2,4,5-T degradation in aqueous media was studied by electro- (EC) and photoelectrochemical (PEC) oxidation methods, which are two of the most important advanced oxidation processes (AOPs) for wastewater treatment. Both EC and PEC experiments were carried out in a single compartment cell under galvanostatic conditions (30 mA cm−2) at 298 K by using 0.05 M Na2SO4 + 200 ppm 2,4,5-T at pH 3 and pH 9, as model solutions. EC oxidation was performed using Sb-doped SnO2, PbO2 and boron doped diamond (BDD) as anodic materials. Besides these anodes, TiO2 in a nanotubular structure (TiO2 NTs) with or without PbO2 dispersed nanoparticles (TiO2::PbO2) were also used for PEC ox…
Light‐Induced On/Off Switching of the Surfactant Character of the o ‐Cobaltabis(dicarbollide) Anion with No Covalent Bond Alteration
2021
Cobaltabis(dicarbollide) anion ([o-COSAN]- ) is a well-known metallacarborane with multiple applications in a variety of fields. In aqueous solution, the cisoid rotamer is the most stable disposition in the ground state. The present work provides theoretical evidence on the possibility to photoinduce the rotation from the cisoid to the transoid rotamer, a conversion that can be reverted when the ground state is repopulated. The non-radiative decay mechanisms proposed in this work are coherent with the lack of fluorescence observed in 3D fluorescence mapping experiments performed on [o-COSAN]- and its derivatives. This phenomenon induced by light has the potential to destruct the vesicles an…
Photochemical behavior in azobenzene having acidic groups. Preparation of magnetic photoresponsive gels
2011
[EN] The photochemistry of three azobenzenes representing contrasting photochemical behaviors is described in the present work. Thus, Methyl Orange (MO, 4-[[(4-dimethylamino)phenyl]-azo]benzenesulfonic acid sodium salt, hereinafter (1) and 4-hydroxyazobenzene-4'-sulfonic acid (2) undergo in water fast photochemical proton shift, with decays in the microsecond timescale. In contrast to the previous cases, azobenzene-4,4'-dicarboxylic acid (3) undergoes photoisomerization in water. This photochemical behavior allows the preparation of aqueous gels with Aerosil as gelating agent (5% weight) exhibiting high cyclability and photoreversible isomerization of the trans to cis (300 nm irradiation) a…
A coumarin based gold(i)-alkynyl complex: a new class of supramolecular hydrogelators.
2014
A phosphine-gold(I)-alkynyl-coumarin complex, [Au{7-(prop-2-ine-1-yloxy)-1-benzopyran-2-one}(DAPTA)] (1), was synthesized and the formation of long luminescent fibers in solution was characterized via fluorescence microscopy and dynamic light scattering. The fibers presented strong blue and green luminescence, suggesting that the gold(I) in the complex increased intersystem crossing due to the heavy atom effect, resulting in a significant increase in triplet emission. The X-ray structure of the fibers indicates that both aurophilic, π–π interactions and hydrogen bonding contribute to their formation in aqueous solvents.
Controlling the oxidation processes of Zn nanoparticles produced by pulsed laser ablation in aqueous solution
2016
We used online UV-VIS optical absorption and photoluminescence spectra, acquired during and after pulsed laser ablation of a Zinc plate in aqueous solution, to investigate the effect of the laser repetition rate and liquid environment on the oxidation processes of the produced nanoparticles. A transient Zn/ZnO core-shell structure was revealed by the coexistence of an absorption peak around 5.0 eV due to Zn surface plasmon resonance and of an edge at 3.4 eV coming from wurtzite ZnO. The growth kinetics of ZnO at the various repetition rates, selectively probed by the excitonic emission at 3.3 eV, began immediately at the onset of laser ablation and was largely independent of the repetition …
Microwave-assisted synthesis of anhydrous CdS nanoparticles in a water-oil microemulsion.
2006
Abstract Microwave irradiation at a frequency of 2.45 GHz and a power ranging between 22 and 30 W was used, in a water–oil microemulsion at 35 ± 2 ° C , to obtain stable, small, crystalline, anhydrous CdS nanoparticles exhibiting enhanced luminescence properties. The process of nanoparticles growth at different irradiation times was followed by UV–vis spectroscopy. It was observed that irradiated nanoparticles grew faster and their size reached a constant value. The final mean nanoparticle diameter was 2.7 nm, smaller than that observed in a non-irradiated sample, in which particle dimensions slowly increased even after 10 h. This finding was confirmed by high resolution transmission electr…
Excitation and emission spectra of LaInO3-based solid solutions doped with Sm3+, Sb3+
2017
Abstract X-ray analysis showed that all the ceramic samples of La 1- x Sm x InO 3 (0.010≤ x ≤0.025) solid solutions were single-phased but the samples of nominal composition of LaIn 0.98 Sb 0.02 O 3 , La 0.98 Sm 0.02 In 0.98 Sb 0.02 O 3 contained a small amount of impurity phase of LaSbO 3 -based solid solutions. It was established that La 0.98 Sm 0.02 InO 3 solid solution under the excitation of 275 nm and 320 nm exhibits the strongest photoluminescence among La 1- x Sm x InO 3 solid solutions with 0.010≤ x ≤0.025. Photoluminescence bands located in wavelength ranges of 550–580 nm, 585–625 nm and 630–680 nm exhibit 2–3 clear maxima each. According to the locations of these maxima we calcul…
Short-lived luminescence of mixed silver halides
1993
Abstract Two kinds of excitonic luminescence were investigated for the entire series of solid solutions, AgBr1−xClx, (0 ⪕ x ⪕ 1). The time-resolved spectra observed around 2.5 eV after both pulsed high-power electron beam and N2-laser irradiations are analyzed in terms of the diffusion-controlled recombination of Frenkel defects Ag0i and Ag2+V-c. It is shown that the effective activation energy of Ag0i migration is a linear function of the composition x; and predominantly two kinds of nearest neighbours contribute to this process. The position of maximum of the excitonic molecule luminescence found in mixed monocrystals and fibers reveals a distinctive dependence on the composition x. Its a…