吸收光谱法测量COIL水含量的实验研究

介绍了吸收光谱测量水蒸汽绝对浓度的方法，标定了实验环境下水蒸汽的吸收系数，并在氧碘化学激光器（COIL）上进行了初步的实验研究，测量结果显示，在常规工作条件下由于BHP温度变化所引起的水汽百分含量变化可以忽略，气体流速是引起水汽含量变化的主要原因。     

原子吸收光谱分析中干扰消除与校正进展

原子吸收光谱分析由于使用锐线光源,是一种选择性比较好的分析方法,但在实际工作中仍存在化学干扰和物理干扰,应采取适当措施予以消除。本文简要地介绍了原子吸收光谱分析中各类干扰的消除和化学计量学在原子吸收光谱分析中的应用情况。     

Synthesis and microwave absorption enhancement of Fe-doped NiO@SiO2@graphene nanocomposites

Fe-doped NiO@SiO₂@graphene nanocomposites have been successfully fabricated for the first time, in which Fe-doped NiO nanoparticles are about 3 nm in diameter. In order to measure their electromagnetic properties, Fe-doped NiO@SiO₂@graphene (25 wt%) wax composites were then prepared. The experimental results show that Fe-doped NiO@SiO₂@graphene nanocomposites exhibit significantly enhanced microwave absorption performance in terms of both the maximum reflection loss value and the absorption bandwidth in comparison with NiO@SiO₂@graphene. The maximum reflection loss of Fe-doped NiO@SiO₂@graphene nanocomposites can reach −51.2 dB at 8.6 GHz with a thickness of 4 mm, and the absorption bandwidth with the reflection loss below −10 dB is 4 GHz (from 7 to 11 GHz). Therefore, this kind of nanocomposites may have the potential as high-efficient absorbers for microwave absorption applications.     

On the measurement of microwave absorption of bulk YBaCuO superconductors in X-band (8–12 GHz)

Microwave absorption at the surface of highT _c YBaCUO superconducting sample has been determined in X-band by measuring VSWR. Power reflectivity >98% has been observed in the frequency range of 8·2–10·5 GHz indicating very low absorption at the surface. At some of the frequencies, however, negligible microwave loss has been observed.     

Oxygen atom density in microwave oxygen plasma

We determined the density of neutral oxygen atoms in microwave plasma using a fiber-optics catalytic probe (FOCP). Plasma was created within a quartz tube with an outer diameter of 5 cm by a 2.45 GHz microwave generator with an output power up to 1000 W. The oxygen flow was varied between 4 and 20 l/h. The O-atom density was found to increase monotonically with the increasing discharge power, and it decreased with the increasing flow rate. The degree of dissociation of oxygen molecules in the plasma column depended largely on the flow rate. At the oxygen flow of 4 l/h, it was about 18% but it decreased to about 6% at the flow of 20 l/h.     

FCC催化剂中锑含量

工业上经常采用锑金属钝化剂防止FCC催化剂失活,但必须严格控制钝化剂的添加量,否则会起副作用,本文采用高温盐消解法处理FCC平衡剂,然后用火焰原子吸收光谱法测定催化剂中锑含量,考察了消解温度、消解时间、酸度等对测量结果的影响,优选出了最佳分析测试条件。所建方法简便、灵敏、准确,该方法回收率在95%-99%之间,变异系数小于2.5%,最小检出限为0.092 mg/L。     

Rapid treatment of polyimide film surfaces using high-density microwave plasma for enhancement of Cu layer adhesion

A high-density microwave plasma has been applied to the surface of polyimide (PI) films as a treatment to enhance the adhesion of sputter-deposited copper layers. A very short (∼5 s) exposure to Ar plasma enhanced the contact angle from 72° to ∼14°. X-ray photoelectron spectroscopy and atomic force microprobe measurements showed an increase in hydrophilic radicals (-OH, -CO) and surface roughness, respectively, following the plasma treatment. Peel strength tests of Cu layers deposited on plasma-treated polyimide films showed that the plasma treatment significantly enhanced Cu layer adhesion.     

点测量激光吸收光谱技术理论分析

点测量吸收光谱技术以饱和吸收为基本原理,可有效克服可调谐二极管激光吸收光谱技术(TDLAS)的线测量缺陷,通过探测光束与一同频的饱和光束交叉来提取交叉位置点处的信息,实现具有毫米级空间分辨能力的点测量。本文对点测量吸收光谱技术进行了详细的理论分析,推导了饱和光束和探测光束在任意交叉角度下的饱和吸收系数,分析了饱和参数对吸收信号的影响。同时提出了一种针对微弱吸收信号的调制方法,推导了饱和光束在高频正弦调制下的探测光一次谐波表达式,并通过数值计算得到了验证。研究还表明,不同阶次谐波信号具有相同的半高宽,并且与无调制时的吸收信号半高宽一致,因此利用多次谐波叠加可进一步提高谱线宽度测量的信噪比。     

Evaluation of plume characteristics of arc-heaters with various oxygen injection systems

Arc-heater plumes generated by various oxygen injection systems were investigated by laser absorption spectroscopy. Firstly, oxygen was directly injected into a high-temperature cathode-jet region through a thoriated-tungsten hollow cathode. Although number density of atomic oxygen was increased, erosion of the cathode was too severe to maintain stable discharge. Then, zirconium was used as a cathode material to reduce cathode erosion by oxidation. As a result, stable discharge was maintained for 3 h with pre-mixed argon–oxygen injection and number density of atomic oxygen was successfully increased.     

Measurement of the characteristics of a point source of x-rays using a picosecond laser plasma

The emissive properties of silicon and aluminum plasmas, produced by 40 psec laser pulses with a peak intensity of greater than 10¹⁴ W/cm², are investigated. The x-ray line spectra of H- and He-like ions, measured with high resolution, are analyzed to determine the plasma parameters. The form of the resonance lines and their intensity with respect to the corresponding dielectronic satellites and the intercombination line are compared with model calculations.Translated from Izmeritelnaya Tekhnika, No. 1, pp. 50–55, January, 2005.     

Optimization of microwave assisted digestion procedure for the determination of zinc, copper and nickel in tea samples employing flame atomic absorption spectrometry

The present paper describes the development of a microwave assisted digestion procedure for the determination of zinc, copper and nickel in tea samples employing flame atomic absorption spectrometry (FAAS). The optimization step was performed using a full factorial design (2(3)) involving the factors: composition of the acid mixture (CMA), microwave power (MP) and radiation time (RT). The experiments of this factorial were carried out using a certified reference material of tea GBW 07605 furnished by National Research Centre for Certified Reference Materials, China, being the metal recoveries considered as response. The relative standard deviations of the method were found below 8% for the three elements. The procedure proposed was used for the determination of copper, zinc and nickel in several samples of tea from Turkey. For 10 tea samples analyzed, the concentration achieved for copper, zinc and nickel varied at 6.4-13.1, 7.0-16.5 and 3.1-5.7 (microg g(-1)), respectively.     

Effect of modulation amplitude on low-field microwave absorption in hafnium-doped Y-Ba-Cu-O

Low-field differential microwave absorption has been studied for hafnium-doped Y-Ba-Cu-O at the first harmonic of modulation field. The effect of modulation amplitude on peak height, peak position and the area under hysteresis curve has been discussed.     

荧光光度法测定室内空气中的甲醛

针对室内空气中低浓度甲醛的测定,在不增加采样流量和采样时间的情况下,本文利用荧光光度法很好地测定了室内空气中低浓度的甲醛,试验证明该方法具有灵敏度高,检出限低,精密度和准确度好的特点。     

Characterization by optical emission spectroscopy of an oxygen plasma used for improving PET wettability

Polymers have excellent bulk physical and chemical properties but usually poor surface properties. For wettability improvement plasma technology is one of the most promising techniques. Several studies about surface modifications of polyethylene terephthalate (PET) exposed to an oxygen plasma have been already carried out. In this work an analysis of the plasma phase by optical emission spectroscopy (OES) has been employed in order to establish a correlation with the surface effects induced by plasma exposition on PET chemical composition and wettability, investigated by X-ray photoelectron spectroscopy (XPS) and water contact angle measurements, respectively. The treatment has been carried out for a time of 60 s at a constant pressure (15 Pa) and at different process powers ranging from 20 to 200 W. As expected, the best performance has been obtained at a power of 200 W due to the larger presence of oxygen radicals (OI) with the assistance of ionic species (OII, O₂⁺) which create dangling bonds on the substrate surface.     

Recombination of atomic oxygen on sintered zirconia at high temperature in non-equilibrium air plasma

High temperature ceramic materials are necessary for the design of primary heat shields for future re-usable space vehicles re-entering atmospheric planet at hypersonic velocity. During the re-entry phase on earth, one of the most important phenomena occurring on the heat shield is the recombination of atomic oxygen and this phenomenon is more or less catalyzed by the material of the heat shield.     

原子吸收光谱法测定红树林中的重金属

本文采用原子吸收光谱法测定白骨壤(Avicenia marina),秋茄树(Kandelia candel)两种红树林中的铜、锌、铅、镉四种重金属含量。回收率在98.3%～104%之间,相对标准偏差在1.57%～3.92%之间,该方法快速、灵敏、准确.     

火焰原子吸收光谱法测定浸渍液中钾、钙、铜、铁

提出了用空气-乙炔火焰原子吸收光谱法进行镉镍电池浸渍液中钾、钙、铜、铁含量的测定,介绍了钾、钙、铜、铁最佳测定条件及呈良好线性范围的浓度,同时对样品消化处理条件及在测定样品中的干扰因素进行了综合考虑。该方法具有很好的灵敏度和重现性,具有方法步骤简单、操作容易、干扰少等特点。测定样品钾、钙、铜、铁含量的相对标准偏差均小于1.0%。标准加入回收率均在97.0%~100.0%范围内。达到了实验室分析与质量的控制。适用于镉镍电池浸渍液中含有较多共同被测离子钾、钙、铜、铁的生产现场控制分析和样品系统分析。     

Measurement of CH4-concentration in HMDSO-containing process plasmas by quantum cascade laser absorption spectroscopy

For thin film deposition or plasma etching often organic precursors are used in the process plasma and related transient species are formed. In general it is not possible to measure the converted quantity of these precursors directly. In the present work we have used a special laser absorption spectroscopy to investigate characteristic molecular lines in the plasma to determine the concentration of stable organic molecules. Quantum cascade laser absorption spectroscopy (QCLAS) is a rather new technique for the precise measurement of absolute molecule concentrations. QCL’s can be operated at room temperature. They emit light within the mid infrared and have similar spectroscopic characteristics to Tunable Diode Lasers (TDL). The commercially available system Q-MACS (Quantum Cascade Laser Measurement and Control System) offers a solid platform for the measurement of absolute molecule concentrations in plasmas and gas mixtures. The used Q-MACS is due to its laser characteristics particularly well suitable for determination of the concentrations of acetylene and methane. Molecular concentrations of methane were measured in hexamethyldisiloxane (HMDSO) containing plasmas, too. The methane concentration was found to depend on rf power and HMDSO flow.     

Formation phenomena of iron oxide-silica composite in microwave plasma and DC thermal plasma

Iron oxide-silica composite was synthesized using atmospheric microwave plasma and DC thermal plasma. There has recently been increasing interest in predicting the final product during vapor phase synthesis using plasma because of difficulty obtaining desirable product. In this study, vapor phase synthesis of iron oxide-silica composite from iron pentacarbonyl (Fe(CO)₅) and tetraethyl orthosilicate (SiC₈H₂₀O₄, TEOS) was conducted using various Fe/Si ratios and different types of plasma to identify the formation mechanism in the Fe-Si-O multi-component system. The morphologies and phase compositions of the synthesized particles were analyzed and compared. The results showed that the Fe/Si ratio and the type of plasma influenced the morphologies and the phase composition. A thermodynamic consideration was introduced to investigate the particle formation phenomena, which could explain the differences induced by varying the Fe/Si ratio and type of plasma. The particle formation mechanism was divided into a condensation step and a diffusion step. At the condensation step, the Fe/Si ratio determined the condensation temperature, which is related to the morphology. At the diffusion step, the quenching rate of the plasma determined the degree of diffusion, which was related to the phase composition and formation of the external layer.