- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Electrical profiling of arsenic-implanted HgCdTe films performed with discrete mobility spectrum analysis
摘要： Results of electrical profiling of an n-on-p junction formed by 190-keV arsenic ion implantation in indium/vacancy–doped Hg0.78Cd0.22Te film are presented. Mobility spectrum analysis in combination with wet chemical etching has been employed for the profiling. After the implantation, a typical n+-n–p structure was observed and three electron species were detected: (a) low-mobility electrons in the 400-500 nm-thick top radiation-damaged n+-layer, (b) mid-mobility electrons also originating from radiation damage and spreading down to 700-900 nm, and (c) high-mobility electrons located in the n-region extending beyond 700-900 nm and down to the p-n junction. A comparison of the extracted electron parameters with the arsenic profile obtained with secondary-ion mass spectroscopy as well as with the defect pattern obtained with transmission electron microscopy allowed for identification of the origin of all the three electron species.
关键词： HgCdTe,arsenic implantation,defects,electrical profiling
更新于2025-09-23 15:23:52
-
A Model Study of the Photochemical Fate of As(III) in Paddy-Water
摘要： The APEX (Aqueous Photochemistry of Environmentally-occurring Xenobiotics) software previously developed by one of us was used to model the photochemistry of As(III) in paddy-field water, allowing a comparison with biotic processes. The model included key paddy-water variables, such as the shielding effect of the rice canopy on incident sunlight and its monthly variations, water pH, and the photochemical parameters of the chromophoric dissolved organic matter (CDOM) occurring in paddy fields. The half-life times (t1/2) of As(III) photooxidation to As(V) would be ~20–30 days in May. In contrast, the photochemical oxidation of As(III) would be much slower in June and July due to rice-canopy shading of radiation because of plant growth, despite higher sunlight irradiance. At pH < 8 the photooxidation of As(III) would mainly be accounted for by reaction with transient species produced by irradiated CDOM (here represented by the excited triplet states 3CDOM*, neglecting the possibly more important reactions with poorly known species such as the phenoxy radicals) and, to a lesser extent, with the hydroxyl radicals (HO?). However, the carbonate radicals (CO3??) could be key photooxidants at pH > 8.5 provided that the paddy-water 3CDOM* is sufficiently reactive toward the oxidation of CO32?. In particular, if paddy-water 3CDOM* oxidizes the carbonate anion with a second-order reaction rate constant near (or higher than) 106 M?1·s?1, the photooxidation of As(III) could be quite fast at pH > 8.5. Such pH conditions can be produced by elevated photosynthetic activity that consumes dissolved CO2.
关键词： paddy-field floodwater,sunlight-induced reactions,arsenic contamination
更新于2025-09-23 15:22:29
-
Nano-size defect layers in arsenic-implanted and annealed HgCdTe epitaxial films studied with transmission electron microscopy
摘要： Optical reflectance and bright-field and high-resolution transmission electron microscopy studies of radiation damage induced by implantation of arsenic ions with 190 keV and 350 keV energy and 1014 cm–2 fluence in molecular-beam epitaxy-grown Hg0.7Cd0.3Te films were performed. A similarity in defect pattern formed by arsenic implantation in Hg1?xCdxTe with x ≈ 0.2 and x ≈ 0.3 straight after the implantation was observed with formation of three nano-size defect layers containing dislocation loops of vacancy- and interstitial-types, single dislocations and lattice deformations. After post-implantation arsenic activation annealing, most of these defects in our Hg0.7Cd0.3Te films, in contrast to Hg0.8Cd0.2Te films, disappeared. This effect is explained by the reduced influence of the electric field of the graded-gap surface layer on the diffusion of charged point defects under annealing.
关键词： HgCdTe,Transmission electron microscopy,Defects,Arsenic implantation
更新于2025-09-23 15:19:57
-
Simultaneously photocatalytic redox and removal of chromium(VI) and arsenic(III) by hydrothermal carbon-sphere@nano-Fe3O4
摘要： The coexistence of multiple-component contaminants, such as Cr(VI) and As(III) in acid mineral drainage, brings more difficulties in the wastewater treatment. This study developed a novel strategy for simultaneous redox conversion and removal of Cr(VI) and As(III) in solution. By employing iron oxide encapsulated in hydrothermal carbon sphere (HCS@Fe3O4), the synergistic photocatalytic reduction of Cr(VI) and oxidation of As(III) were markedly accelerated under simulated solar light irradiation. The transformed Cr(III) and As(V) were readily removed by forming Cr(OH)3 and FeAsO4 precipitates. The Fe(III)/Fe(II) cycle in the system, which was greatly reinforced by photocatalysis in the presence of HCS@Fe3O4, has been demonstrated to be critical in the redox of Cr(VI) and As(III). It can keep sufficient Fe(II) in solution to both directly reduce Cr(VI) and promote the generation of ?OH for the oxidation of As(III). These findings provide an effectively synergistic conversion and removal strategy for implications in multiple-contaminated water treatment.
关键词： chromium(VI),carbon sphere@Fe3O4,photocatalytic redox,arsenic(III)
更新于2025-09-19 17:15:36
-
Comparative <i>in vivo</i> imaging of arsenic and phosphorus in <i>Pteris vittata</i> gametophyte by synchrotron μ-XRF and radioactive tracer techniques
摘要： Comparative in vivo imaging of arsenic and phosphorus in Pteris vittata gametophyte by synchrotron μ-XRF and radioactive tracer techniques. Synchrotron μ-XRF and autoradiography complementally revealed the different behavior of arsenic and phosphorus in Pteris vittata L. at a high spatial resolution with its living state. We found that P. vittata develops the several sequestration mechanisms of As from important biological functions at the different growth stages. Some of them relate to the activities in the roots of the sporophyte and the reproduction on the gametophyte.
关键词： arsenic hyperaccumulator,autoradiography,synchrotron X-ray analysis
更新于2025-09-19 17:15:36
-
Atomization of arsenic hydride in a planar dielectric barrier discharge: Behavior of As atoms studied by temporally and spatially resolved optical emission spectrometry
摘要： The excitation mechanism of arsenic atoms in a planar shaped dielectric barrier discharge (DBD) atomizer with sputtered grid shaped electrodes was studied by optical emission spectrometry (OES) with resolution in time and space. Due to the shape of the electrodes, the DBD design provides optical access to the plasma not only in end-on position but also in side-on direction. By means of an iCCD camera with nanosecond time resolution coupled to a monochromator it was shown that the spatial and temporal development of the plasma emission depends on the discharge gas nature (Ar, He). Applying argon, a dense and constricted plasma filament is formed, whereas in helium a much more homogeneous plasma is ignited. The impact of both plasmas on the emission signal of arsenic atoms was studied employing analyte introduction via hydride generation. The excitation of arsenic temporally follows the emission signal of helium or argon and is spread across the whole discharge volume. The basic discharge propagation dynamics showed similarities to previously presented results obtained by OES in a capillary DBD.
关键词： Arsenic,Optical emission spectrometry,Dielectric barrier discharge
更新于2025-09-19 17:15:36
-
GaAs1-Sb /GaAs single quantum well for long wavelength photonic devices
摘要： Carrier dynamics in GaAs1-xSbx/GaAs single quantum well (SQW) is investigated in this report. With Sb incorporation (x = 0.352, 0.405), the photoluminescence (PL) emission peaks exhibit characteristics of GaAs1-xSbx in low temperature and GaAs above 200 K. In power dependent PL, the intensities reveal sublinear power relationship as localized and free excitons are involved at 10 K. The power exponent is in agreement with the degree of localization energy present in SQW and carrier kinetics for various recombination mechanisms are also discussed by deriving respective rate equations.
关键词： X-ray diffraction,Gallium Arsenic-antimonide,Photoluminescence,Heterostructure,SQW
更新于2025-09-19 17:13:59
-
Raman study of laser-induced formation of IIa??VI nanocrystals in zinc-doped Asa??S(Se) films
摘要： Zn-doped As2Se3 and As2S3 films were prepared by thermal evaporation. Their amorphous structure was confirmed by Raman spectroscopy. Zinc chalcogenide nanocrystals can be formed in the films under laser irradiation due to the photoenhanced diffusion of atoms in the arsenic chalcogenide films, which enables aggregation of Zn and S(Se) atoms in nanocrystals. For As2S3:Zn films, not only ZnS, but also ZnO crystallites can be formed under irradiation with UV laser light due to oxidation of the film surface with abundant zinc atoms.
关键词： Raman scattering,Amorphous films,II–VI nanocrystals,Arsenic chalcogenides
更新于2025-09-19 17:13:59
-
Impact of composition and ex-situ laser irradiation on the structure and optical properties of As-S-based films synthesized by PECVD
摘要： Synthesis of amorphous chalcogenide As-S-based films with arsenic content from 35 to 55 at. % by a PECVD method is achieved. The composition-structure-optical properties relationship is revealed. Varying the composition of the films from As35S65 to As55S45 is accompanied by a change of the dominant structural units: from AsS3/2 pyramids to cage-like As4S4 and As4S3 units, causing a considerable decrease of the optical band gap from 2.42 to 1.87 eV. It has been found out that modification by a focused laser irradiation (473 nm) leads to formation of micro/nanocrystalline inclusions feasible for applications in medicine, optoelectronics and integrated optics. The type of inclusions depends on the dominant structural units of the initial films. In case of the As55S45 film appearance of the dimorphite crystalline phase (α-As4S3) is observed. The ex-situ laser modification of the As-S films leads to appearance of a photoluminescence emission, and its maximum position shifts from 1.8 to 2.05 eV depending on the initial film stoichiometry.
关键词： Optical properties,Arsenic sulfide,Chalcogenide films,Nanocrystals formation,PECVD
更新于2025-09-16 10:30:52
-
Synthesis and application of a surface ionic imprinting polymer on silica-coated Mn-doped ZnS quantum dots as a chemosensor for the selective quantification of inorganic arsenic in fish
摘要： A novel room temperature phosphorescence chemosensor probe has been successfully developed and applied to the selective detection and quantification of inorganic arsenic (As(III) plus As(V)) in fish samples. The prepared material (IIP@ZnS:Mn QDs) was based on Mn-doped ZnS quantum dots coated with (3-aminopropyl) triethoxysilane and an As(III) ionic imprinted polymer. The novel use of vinyl imidazole as a complexing reagent when synthesizing the ionic imprinted polymer guarantees that both inorganic arsenic species (As(III) and As(V)) can interact with the recognition cavities in the ionic imprinted polymer. After characterization, several studies were performed to enhance the interaction between the targets (As(III) and As(V) ions) and the IIP@ZnS:Mn QDs nanoparticles. The optimization and validation process showed that the composite material offers high selectivity (high imprinting factor) for inorganic arsenic species. The limit of quantification for total inorganic As was 29.6 μg kg?1, value lower than the EU/EC regulation limits proposed for other foodstuffs than fish, such as rice. The proposed method is therefore simple, requires short analysis times and offers good sensitivity, precision (inter-day relative standard deviations lower than 10%), and quantitative analytical recoveries. The method has been successfully applied to assess total inorganic arsenic in several fishery products, showing good agreement with the total inorganic arsenic concentration (As(III) plus As(V)) found after applying other advanced and expensive methods such those based on high-performance liquid chromatography hyphenated to inductively coupled plasma-mass spectrometry.
关键词： Ionic imprinted polymer,Silica-coated Mn-doped ZnS quantum dots,Fish,Room temperature phosphorescence,Chemosensor probe,Inorganic arsenic
更新于2025-09-16 10:30:52