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171.
A new reactor and a novel in-situ sampling technique were developed for the study of the synthesis of CeO2 powders produced from dissolved cerium nitrate salts. The conical reactor minimized particle recirculation and provided a
highly symmetrical and undisturbed plasma flow suitable for the analysis of the phenomena affecting the formation of CeO2 powders. Both a calorimetric study of the reactor and a thermodynamic analysis of CeO2 formation were conducted. The sampling probe is described and near-isokinetic sampling was achieved. The sampled particles
were collected using a miniature wet collection system, i.e. a mist atomizer and a custom-made spray chamber. A numerical
simulation of the velocity and temperature fields of the plasma gas in the reactor was done using Fluent. A comprehensive
droplet-to-particle formation mechanism presented elsewhere is revisited and expanded based on calorimetry, thermodynamics
of CeO2 formation, numerical simulations and collected particles. No traces of other oxidation states other than CeO2 were found. 相似文献
172.
ZHANG Shu-dong KONG Xiang-he ZHU Xiang-jun WANG Yan JIANG Su-rong 《高等学校化学研究》2006,22(5):621-625
IntroductionReactions of metal ions with neutral molecules orclusters produce a variety of metal complex ions andother new series of cluster ions including cations andanions.The laser ablation-molecular beam(LA-MB)method has marked its relevance in the st… 相似文献
173.
T. Yasuda T. Okuno M. Miyama H. Yasuda 《Journal of polymer science. Part A, Polymer chemistry》1994,32(10):1829-1837
Plasma treatment of a polymeric surface could involve at least three major mechanisms: (1) direct interaction of reactive species in the low-temperature plasma state with the surface (line of sight irradiation effect), and (2) chemical reactions of plasma-induced reactive species with the surface, and (3) reactions among reactive species and the surface (plasma polymerization). The first and the third effects are considered to be limited to the surfaces which directly contact with plasma (glow). The second effect is not limited to the surfaces that contact with plasma state but can penetrate beyond the plasma zone by diffusion. Using an assembly of fibers, of which only the top layer contacts with plasma (glow), the penetration of chemical changes caused by plasma exposure was investigated. Results indicate that the fluorination effect (incorporation of fluorine-containing moieties on the surface of polymeric substrate) penetrates through a considerable thickness of the assembly of fibers, depending on the porosity (gas permeability) of the system. Chemical reactions of plasma-induced (chemically) reactive but nonpolymerizing species with the substrate fibers seems to predominate. The direct interactions of energetic species, such as ions, electrons, and electronically excited species, with polymeric surfaces seems to play relatively minor roles in the plasma treatment investigated. The major role of plasma, in this case, seems to be creating such chemically reactive species. © 1994 John Wiley & Sons, Inc. 相似文献
174.
The decomposition of N2O in a 13.56-MHz parallel-plate system was studied usingin situ Fourier transform infrared (FTIR) spectroscopy. Areas of two infrared absorption bands of N2O recorded at 8 cm–1 resolution were used to estimate relative gas-phase dissociation as a function of rf power and flow rate at 500 mT. Flow rate was found to strongly affect band areas over the range of powers investigated (10–90 W). The effect of rf power on band areas diminished above 40 W, probably due to poor plasma confinement. Distortion of the band shapes by the plasma permitted rotational temperatures to be estimated. Rotational temperature increased essentially linearly with power at constant flow rate, reaching 450 K at 80 W, but was independent of flow rate at constant power. Rotational temperatures were also found to depend on the temperature of the electrodes, which were heated by plasma exposure. No infrared-active product species were observed even under batch conditions where all N2O was irreversibly dissociated. This lack of detectable products and a 50% pressure rise observed in a batch study suggest that N2 and O2 are the primary stable discharge products. 相似文献
175.
Marek BryjakIrena Gancarz Gryzelda Po?niakW?odzimierz Tylus 《European Polymer Journal》2002,38(4):717-726
The effect of NH3 and NH3/Ar plasma on ultrafiltration polysulfone membranes have been studied. Results of contact angle, FTIR-ATR and X-ray photoelectron spectroscopy experiments clearly showed that both plasmas introduced hydrophilic, nitrogen- and oxygen-containing moieties on the polymer surface and that NH3/Ar plasma was more efficient. That plasma was also more aggressive--signs of strong etching could be seen on the SEM pictures. Redeposition of etched material seemed to take place inside the pores. On the contrary, ammonia plasma was soft and caused cleaning the surface and pores enlargement. Performance of ammonia plasma modified membranes was greatly improved and independent on solution pH. The last observation proved amphoteric character of the surface. NH3/Ar plasma treatment gave membranes of acidic surface and filtration indices not so good as for ammonia plasma. 相似文献
176.
A multi-element Saha–Boltzmann plot method is proposed for the determination of the temperature and the relative number density in laser-induced plasmas, assuming local thermodynamic equilibrium and stoichiometry conservation. The method has been applied to the characterization of a plasma generated with a Cu–Fe–Ni–Mn alloy, using a Nd:YAG laser in air at atmospheric pressure. Spectra of the local emissivity have been obtained by spatial deconvolution of the intensity spectra, obtained with spatial resolution. Saha–Boltzmann plots obtained from the emissivities of 58 spectral lines of Fe I, Fe II, Ni I, Ni II, Mn I and Mn II have been fitted to linear behavior with high correlation, which shows the validity of the equation proposed. Radial distributions of the temperature and number densities of neutral atoms and ions have been determined. The results obtained reinforce the initial considerations of local thermodynamic equilibrium and conservation of stoichiometry. The proposed equation can also be applied to only one ionization species (multi-element Boltzmann plot). Spatially-integrated measurements of the plasma emission have also been performed to show that, in this case, the application of the method to the line intensities provides the two different apparent temperatures for neutral atoms and ions. 相似文献
177.
The photon flux of vacuum ultraviolet (VUV) and ultraviolet (UV) radiation of a hydrogen plasma with and without a MgF2window was recorded by fluorescence measurements of sodium salicylate layers. After the compensation of the MgF2absorption by increasing the input power into the plasma source, a comparison between afterglow hydrogen plasma and VUV treatments was made. Polyethylene (PE), polypropylene (PP), and polystyrene (PS) were treated either with VUV radiation or with remote hydrogen plasma and mass loss and CH absorption loss were measured by a quartz crystal microbalance and by infrared reflection absorption spectroscopy, respectively. In the case of PE the effects of both treatments were found to be very similar white for PP slight differences were observed. For the actual set of experimental conditions, the radiation component is largely responsible for the efficiency of the plasma treatment. VUV and remote hydrogen plasma treatments of PS showed only a negligible loss of mass and CH absorption. 相似文献
178.
A sensitive and selective high-performance liquid chromatographic assay for the quantification of ketanserin and ketanserinol in human plasma was developed and validated. The procedure involves extraction of ketanserin and ketanserinol from plasma using an Extrelut NT-1 solid-phase extraction column. The chromatograph was equipped with a Hypersil BDS column (100 x 4.5 mm, 3 micro m particle size). Separation was performed with a mixture of acetate buffer 0.01 M, pH 4.9-methanol-acetonitrile (52:40:8, v/v/v). Detection was performed with fluorescence detection (lambda(ex) = 332 nm and lambda(em) = 410 nm). Calibration curves were linear (r(2) = 0.999) in the range 0-400 ng/mL for both ketanserin and ketanserinol. The repeatability coefficient for ketanserin and ketanserinol was 3.1 and 3.0%, respectively. The reproducibility coefficient for ketanserin and ketanserinol was 10.5 and 9.1%, respectively. The limit of quantification for both ketanserin and ketanserinol was 2.0 ng/mL. The mean recovery yield for both ketanserin and ketanserinol was 60%. In an 8 h work day approximately 60 samples, including calibration and reference standards, could be processed. 相似文献
179.
气动雾化进样微波等离子体炬(MPT)原子荧光光谱法测定锌的研究 总被引:5,自引:0,他引:5
本文将水溶液雾化进样与微波等离子体炬原子荧光光谱法联用,建立了HCL-MPT-AFS测定Zn的新方法。讨论了实验条件的选择问题以及溶液中共存离子对测定Zn的影响,本文所推荐的方法具有较高的灵敏度和精密度,并将其用于实际样品分析。 相似文献
180.