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721.
A sensitive anodic stripping voltammetric procedure at the bismuth film electrode (BFE) for trace analysis of copper (II) in the presence of gallium is presented. The new protocol circumvents the problems of overlapping stripping signals between copper and bismuth that previously hampered the analysis of copper at the BFE. The results illustrate that the addition of gallium not only improves the reproducibility of the bismuth stripping signal but also facilitates much improved resolution between the stripping signals of bismuth and copper. Investigations into the effect of gallium on the stripping response of copper and bismuth were studied showing a 4:1 gallium:copper mole ratio produces optimum signals from bismuth and copper indicating a possible stoichiometric relationship. Optimisation of other key variables including electrolyte composition, accumulation parameters and appropriate waveform settings were studied and optimised. The optimised procedures show a range of linear calibration plots (R2 > 0.994) ranging from 2 to 500 μg L−1 and the relative standard deviation for a solution containing 100 μg L−1 copper was 3.7% (n = 10). Utilising an accumulation time of 300 s the limit of detection was 1.4 μg L−1 (S/N = 3). This technique was successfully applied to the analysis of copper in tap water representing the first successful copper determination in real samples using the BFE. 相似文献
722.
Wanda Ziemkowska Eliza Ja?kowska Micha? K. Cyrański 《Journal of organometallic chemistry》2011,696(10):2079-2085
Alkyl aluminum-, gallium-, and indium oxamidates Me4Al2(dpoa) (1), Me4Al2(dboa) (2), Me4Ga2(dpoa) (3), Me4Ga2(dboa) (4), tBu4Ga2(dpoa) (5) and Me4In2(dboa) (6) (dpoa-H2 = N,N′-diphenyloxamide, dboa-H2 = N,N′-di-tert-butyloxamide) have been prepared and characterized. Compounds 1-3, 5 and 6 exist in the form of isomers a only, with a skeleton framework of the molecules consisting of two almost flat, coplanar and fused MNOC2 (M = Al, Ga, In) heterocyclic rings. Depending on the reaction conditions, the compound 4 was obtained as the isomer 4a or as the mixture of two isomers 4a and 4b. Molecular structures of the compounds 1a-6a have been determined by X-ray crystallography. A structure of the isomer 4b was proposed on the basis of NMR spectroscopy. A skeleton framework of the 4b molecule consists of two fused different cycles, GaO2C2 and GaN2C2. 相似文献
723.
Xiaojing GongKe Xu Jianfeng WangHui Yang Lifeng BianJingping Zhang Zijian Xu 《Physica B: Condensed Matter》2011,406(1):36-39
We studied the atomic assembly mechanisms of non-polar GaN films by the molecular dynamics method as a function of the N:Ga flux ratio at a fixed adatom energy on non-polar planes. Our study revealed that high quality crystal growth occurred only when off-lattice atoms (which are usually associated with amorphous embryos or defect complexes) formed during deposition were able to move to unoccupied lattice sites by thermally activated diffusion processes, which attests to the experimental difficulties in obtaining smooth surfaces due to dense stacking faults lying in non-polar GaN. Furthermore, surface structures on different planes played an important role. We further suggested favorable conditions for growing high quality GaN films and nano-structures along non-polar directions. 相似文献
724.
V. Suresh Kumar J. KumarP. Puviarasu S. Munawar BashaD. Kanjilal K. Asokan 《Physica B: Condensed Matter》2011,406(22):4210-4213
Metal-organic chemical vapor deposition (MOCVD) grown n-type Gallium nitride (GaN) has been irradiated with 100 MeV Ni9+ ions at room temperature. Atomic force microscopy (AFM) images show the nano-clusters' formation upon irradiation and the irradiated GaN surface roughness increases with the increasing ion fluences. High-resolution X-ray diffraction (HR-XRD) analysis reveals the formation of Ga2O3 due to the interface mixing of GaN/Al2O3 upon irradiation. FWHM values of GaN (0 0 0 2) increases due to the lattice disorder. Photoluminescence studies show reduced band edge emission and yellow luminescence (YL) intensity with the increasing ion fluences. Change in the band gap energy between 3.38 and 3.04 eV was measured by UV-visible optical absorption spectrum on increasing the ion fluences. 相似文献
725.
An influence of electronic states at an insulator/GaN interface on the behavior of excess holes in an ultraviolet-illuminated metal/ SiO2/n-GaN structure has been studied by numerical simulations for weak (gate bias of −0.1 V ) and strong (−1 V ) depletion, in a wide range of excitation light intensities (from 1010 to 1020 photons cm−2 s−1) and for various bulk carrier lifetimes (from 1 to 100 ns). It has been found that the interface states with densities of 1012 eV −1 cm−2 dramatically reduce the total (integrated in the whole GaN layer) density of photogenerated holes and thus degrade the sensitivity of the metal/insulator/GaN-based photodetector. 相似文献
726.
The promising structural features of the defect spinel-type oxide γ-Ga2O3 and its application potential as a host for new nanoscale solid solutions have been far less explored than its analog γ-alumina, which is widely used in catalysis. Therefore, new synthetic approaches are required to access transition metal-doped γ-Ga2O3 materials on the nanoscale. We have established the first microwave–hydrothermal route for the challenging incorporation of Cu2+ ions into a nanostructured γ-Ga2O3 matrix. Homogeneous γ-Ga2O3:Cu2+ materials with high surface areas are formed within less than 30 min, and the copper content can be adjusted through the synthetic parameters. The copper distribution within the spinel matrix was analyzed with a wide range of compositional, structural, spectroscopic and magnetic characterizations. 相似文献
727.
728.
《Current Applied Physics》2015,15(11):1445-1452
The propagation length of surface plasmon polaritons (SPPs) is investigated experimentally using a 1D metallic grating fabricated on a higher refractive index substrate (Gallium Phosphide, GaP). The experimentally measured value propagation length of the SPP (LSPP) at 785 nm wavelength is 13.33 ± 0.13 μm, which is close to the theoretical value of the LSPP on an ideal Au-thin film. The SPP resonance observed in far-field measurements confirms the underlying process and the related effects on the LSPP measured by scanning near field optical microscope (SNOM). Far-field measurements shows that LSPP is associated with the full width at half maximum (FWHM) of the SPP resonance which in-turn associated with in-plane directional scattering of the SPP. 相似文献
729.
Siama Basharat Robert Palgrave Derek A. Tocher 《Journal of organometallic chemistry》2008,693(10):1787-1796
Structural studies by X-ray crystallography have been carried out for a range of diorganoalkoxogallanes incorporating donor-functionalized ligands. The compounds [Et2Ga(μ-OR)]2 (1, R = CH2CH2NMe2; 2, R = CH(CH3)CH2NMe2; 3, C(CH3)2CH2OMe; 4, R = CH(CH2NMe2)2) adopt dimeric structures with a planar Ga2O2 ring, and each gallium atom is coordinated in a distorted trigonal bipyramidal geometry. Low pressure chemical vapor deposition (CVD) of 2 and 4 resulted in the formation of oxygen deficient gallium oxide thin films on glass. However, the reaction of Et3Ga and ROH (R = CH2CH2NMe2, CH(CH3)CH2NMe2, C(CH3)2CH2OMe, CH(CH2NMe2)2) in toluene under aerosol assisted (AA)CVD conditions afforded stoichiometric Ga2O3 thin films on glass. This CVD technique offers a rapid, convenient route to Ga2O3, which involves the in situ formation of diethylalkoxogallanes, of the type [Et2Ga(μ-OR)]2, the structures of which are described in this paper. The gallium oxide films were deposited at 450 °C and analyzed by scanning electron microscopy (SEM), X-ray powder diffraction, wavelength dispersive analysis of X-rays (WDX), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. 相似文献
730.
The reaction of Al, Ga, or In metals and H5IO6 in aqueous media at 180 °C leads to the formation of Al(IO3)3, Ga(IO3)3, or In(IO3)3, respectively. Single-crystal X-ray diffraction experiments have shown In(IO3)3 contains the Te4O9-type structure, while both Al(IO3)3 and Ga(IO3)3 are known to exhibit the polar Fe(IO3)3-type structure. Crystallographic data for In(IO3)3, trigonal, space group , a=9.7482(4) Å, c=14.1374(6) Å, V=1163.45(8) Z=6, R(F)=1.38% for 41 parameters with 644 reflections with I>2σ(I). All three iodate structures contain group 13 metal cations in a distorted octahedral coordination environment. M(IO3)3 (M=Al, Ga) contain a three-dimensional network formed by the bridging of Al3+ or Ga3+ cations by iodate anions. With In(IO3)3, iodate anions bridge In3+ cations in two-dimensional layers. Both materials contain distorted octahedral holes in their structures formed by terminal oxygen atoms from the iodate anions. The Raman spectra have been collected for these metal iodates; In(IO3)3 was found to display a distinctively different vibrational profile than Al(IO3)3 or Ga(IO3)3. Hence, the Raman profile can be used as a rapid diagnostic tool to discern between the different structural motifs. 相似文献