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141.
A chemical flux of sulfur hexafluoride (SF6) in conjunction with low-energy Ar-ion bombardment has been used for chemically assisted ion beam etching (CAIBE) of silicon and silicon dioxide. The study has shown a large degree of independent control over the selectivity and anisotropy in dry etching. The total etch rate could be controlled by varying either the Ar-ion milling parameters or the chemical flux of SF6. Etch rate enhancement of 7–8 for silicon and 3–4 for silicon dioxide have been obtained over pure physical etching. 相似文献
142.
143.
Klaus van Benthem Stephan Krämer Wilfried Sigle Manfred Rühle 《Mikrochimica acta》2002,138(3-4):181-193
An understanding of the correlation between microstructures and properties of materials require the characterization of the
material on many different length scales. Often the properties depend primarily on the atomistics of defects, such as dislocations
and interfaces. The different techniques of transmission electron microscopy allow the characterization of the structure and
of the chemical composition of materials with high spatial resolution to the atomic level: high resolution transmission electron
microscopy allows the determination of the position of the columns of atoms (ions) with high accuracy. The accuracy which
can be achieved in these measurements depends not only on the instrumentation but also on the quality of the transmitted specimen
and on the scattering power of the atoms (ions) present in the analyzed column.
The chemical composition can be revealed from investigations by analytical microscopy which includes energy dispersive X-ray
spectroscopy, mainly quantitatively applied for heavy elements, and electron energy-loss spectroscopy. Furthermore, the energy-loss
near-edge structure of EELS data results in information on the local band structure of unoccupied states of the excited atoms
and, therefore, on bonding. A quantitative evaluation of convergent beam electron diffraction results in information on the
electron charge density distribution of the bulk (defect-free) material.
The different techniques are described and applied to different problems in materials science. It will be shown that nearly
atomic resolution can be achieved in high resolution electron microscopy and in analytical electron microscopy. Recent developments
in electron microscopy instrumentation will result in atomic resolution in the foreseeable future. 相似文献
144.
Reactive constituents have been investigated in a molecular beam generated in the cathode surface glow area and surface boundary layer. Mixtures of nitrogen and hydrogen form NHx(x=0–4) compounds, which are of relevance in heterogeneous, plasma vs. metal nitriding reactions. Ammonia decomposition leads to NHx(x=2–4). Strong cataphoretic enrichment of hydrogen has been observed in the cathode glow area. Heterogeneous reactions of NHx with iron lead to the formation of iron nitrides via intermediates such as FeNH2–3. In a pulsed d.c. glow discharge, increased sputtering and decreased hydrogen enrichment have been observed. 相似文献
145.
Zeng -Gui Chen 《International Journal of Infrared and Millimeter Waves》1993,14(2):197-211
A cylindrical waveguide gyro-peniotron amplifier is analysed theoretically in this paper. By a ballistic method and directly using the energy conservation in the beam-wave system, a set of interaction equations for the cylindrical waveguide gyro-peniotron amplifier is derived. Computer simulation shows that under defined conditions an interaction efficiency of 47%, an output power of 240kW at a gain of 22. 5 dB and a 3 dB-instantaneous bandwidth of 1. 9% for a central frequency of 35GHz, TE03 mode gyro-peniotron amplifier could be achieved. The influence of the operation parameters on the amplifier performance is also presented. 相似文献
146.
Diana I. Martin Elena Mateescu Gabriela Craciun Daniel Ighigeanu Adelina Ighigeanu 《Radiation Physics and Chemistry》2002,64(5-6):423-428
Results obtained by accelerated electron beam, microwave and simultaneous microwave and electron beam application in the chemistry of acrylamide and acrylic acid copolymers (polymeric flocculants used for wastewater treatment) are presented. Comparative results concerning the molecular weight and Huggins’ constant for the acrylamide and acrylic acid copolymers obtained by classical heating, microwave heating, electron beam irradiation and simultaneous microwave and electron beam treatment are reported. Microwave heating produces high water solubility of the polymeric flocculants but median molecular weight values. Electron beam irradiation gives high molecular weight values but associated with a cross-linked structure (poor water solubility) while microwave energy addition to electron beam energy gives simultaneously high molecular weight values and high water solubility. 相似文献
147.
A. Castaeda Facio R. Benavides M.E. Martínez Pardo R. Uribe 《Radiation Physics and Chemistry》2007,76(11-12):1720-1723
PVC samples with lead-free and lead-base stabilizer, containing TMPTMA (trimethylolpropane trimethacrylate) as a crosslinker and DOP (2-ethylhexyl phthalate) as a plasticizer, were electron beam treated at different doses (2–200 kGy) and characterized to evaluate crosslinking and other several properties, as a continuation of our previously reported paper, where these PVC formulations, typical for wire and cable applications, underwent gamma irradiation. The PVC was formulated with two different stabilizing systems: Ca/Zn and dibasic lead phthalate for comparison, to use them as jackets for a 22 wire gage (AWG). Small samples of the jacketed wires were irradiated in an industrial Dynamitron electron accelerator for the corresponding doses, along with two dosimetric systems: radiochromic thin film and alanine pellets dosimeters. The maximum dose applied was decided as the crosslinking increased, until the gel content was stable. The dose of 200 kGy was the condition for the highest crosslinking, so most of the wire was irradiated at such dose. Chemical and mechanical evaluations were carried out to the irradiated wire. The results show that 200 kGy was too high dose for the materials, since an important degradation is observed for the Ca/Zn systems. Unfortunately, such dose affects basically to CaZn formulations, which showed much poorer performance than classical lead-containing compositions. The results also indicate that gel content is not the best way of deciding the optimum condition for irradiation. 相似文献
148.
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
149.
As a new concept for the design of effective photocatalysts, an ion beam technology using accelerated metal ions, a metal ion implantation and an ionized cluster beam (ICB) method, have been applied to design unique photocatalysts. The metal ion implantation of TiO2 and Ti-containing zeolites with highly accelerated metal ions (V+, Cr+, etc.) is useful in designing photocatalysts that can operate efficiently under visible light irradiation. Also, an ICB method with a low acceleration energy is useful in preparing transparent TiO2 thin films on various types of substrates for the efficient photocatalytic degradation of pollutants diluted in water and air. The combination of the ICB method and metal ion implantation can develop the TiO2 thin films that are able to operate not only under UV light but also under visible light irradiation. 相似文献
150.
V.L. Auslender I.V. Gornakov V.M. Radchenko E. Shtarklev V.O. Tkachenko L.A. Voronin 《Radiation Physics and Chemistry》2007,76(11-12):1792-1794
The report describes electron beam electromagnetic forming system, which is destined for irradiation of cylindrical long goods, specifically for PE tubes 160 mm diameter. System consists of electromagnet, power supply units, beam distributions control units, etc. for use at an electron accelerator at 5 MeV and 50 kW. The particular geometry of the magnet poles and their mutual arrangement are creating an irradiation field that allows the electrons to irradiate the surface of the product close to 90°. 相似文献