微晶酚酞富集-分光光度法测定痕量Zn(II)

建立了一种利用修饰有结晶紫(CV^＋)的微晶酚酞作为固态吸附剂分离富集溶液中痕量Zn(II)的新方法, 富集后的Zn(II)含量可直接用光度法测定. 控制一定条件, Zn(II)能与常见阳离子Ni(II), Cd(II), Al(III), Ca(II), Mg(II), Co(II), Mn(II), Cu(II), Pb(II), Fe(III)等完全分离, 且富集时基本不受, , Br^－, Cl^－, I^－,等阴离子影响. 微晶酚酞对Zn(II)的吸附容量为25.8 mg/g; 富集因数可达200倍, 回收率在97.7%～102%之间, RSD小于2.7%. 该方法已成功应用于实际水样中Zn(II)的富集测定, 结果令人满意.     

The role of hydrogen in hydrogenated microcrystalline silicon film and in deposition process with VHF-PECVD technique

The role of hydrogen in hydrogenated microcrystalline silicon ($\mu $c-Si:H) thin films in deposition processes with very high frequency plasma-enhanced chemical vapour deposition (VHF-PECVD) technique have been investigated in this paper. With \textit{in situ} optical emission spectroscopy (OES) diagnosis during the fabrication of $\mu $c-Si:H thin films under different plasma excitation frequency $\nu _{\rm e }$ (60MHz--90MHz), the characteristic peak intensities ($I_{{\rm SiH}^*}$, $I_{{\rm H}\alpha^*}$ and $I_{{\rm H}\beta ^*}$) in SiHVHF-PECVD技术 氢化微晶硅 光发射光谱 薄膜学VHF-PECVD technique, hydrogenated microcrystalline silicon, role of hydrogen, optical emission spectroscopyProject supported by the Natural Science Foundation of Guangdong Province, China (Grant No 05300378), the State Key Development Program for Basic Research of China (Grant Nos G2000028202 and G2000028203) and the Program on Natural Science of Jinan University, Guangzhou, China (Grant No 51204056).2005-11-252005-11-252006-01-05The role of hydrogen in hydrogenated microcrystalline silicon （μc-Si：H） thin films in deposition processes with very high frequency plasma-enhanced chemical vapour deposition （VHF-PECVD） technique have been investigated in this paper. With in situ optical emission spectroscopy （OES） diagnosis during the fabrication of μc-Si：H thin films under different plasma excitation frequency Ve （60MHz-90MHz）, the characteristic peak intensities （IsiH＊, IHα＊ and IHβ＊ ） in SiH4＋H2 plasma and the ratio of （IHα＊ ＋ IHβ＊ ） to IsiH＊ were measured; all the characteristic peak intensities and the ratio （IHα＊ ＋ IHβ＊ ）/IsiH＊ are increased with plasma excitation frequency. It is identified that high plasma excitation frequency is favourable to promote the decomposition of SiH4＋H2 to produce atomic hydrogen and SiHx radicals. The influences of atomic hydrogen on structural properties and that of SiHx radicals on deposition rate of μc-Si：H thin films have been studied through Raman spectra and thickness measurements, respectively. It can be concluded that both the crystalline volume fraction and deposition rate are enhanced with the increase of plasma excitation frequency, which is in good accord with the OES results. By means of FTIR measurements, hydrogen contents of μc-Si：H thin films deposited at different plasma excitation frequency have been evaluated from the integrated intensity of wagging mode near 640 cm^-1. The hydrogen contents vary from 4% to 5%, which are much lower than those of μc-Si：H films deposited with RF-PECVD technique. This implies that μc-Si：H thin films deposited with VHF-PECVD technique usually have good stability under light-soaking.     

气体滞留时间对高速沉积的微晶硅薄膜性能的影响分析

实现高速沉积对于薄膜微晶硅太阳电池产业化降低成本是一个重要手段.采用超高频等离子体增强化学气相沉积(VHF-PECVD)技术，实现了微晶硅硅薄膜的高速沉积，并通过改变气体总流量改变气体滞留时间，考察了气体滞留时间在化学气相沉积(CVD)过程中对薄膜的生长速率以及光电特性和结构特性的影响.采用沉积速率达到12?/s的高速微晶硅工艺制备微晶硅电池，电池效率达到了5.3％. 关键词： 气体滞留时间 高速沉积 微晶硅 超高频等离子体增强化学气相沉积     

Effects of Moisture on the Mechanical Properties of Microcrystalline Cellulose and the Mobility of the Water Molecules as Studied by the Hybrid Molecular Mechanics–Molecular Dynamics Simulation Method

A hybrid molecular mechanics–molecular dynamics simulation method has been performed to study the effects of moisture content on the mechanical properties of microcrystalline cellulose (MCC) and the mobility of the water molecules. The specific volume and diffusion coefficient of the water increase with increasing moisture content in the range studied of 1.8–25.5 w/w%, while the Young's modulus decreases. The simulation results are in close agreement with the published experimental data. Both the bound scission and free‐volume mechanisms contribute to the plasticization of MCC by water. The Voronoi volume increases with increasing moisture content. It is related to the free volume and the increase enhances the mobility of the water molecules and thus increases the coefficient of diffusion of the water. Moreover, with increasing moisture content, the hydrogen bonding per water molecule between MCC–water molecules decreases, thus increasing the water mobility and number of free water molecules. © 2019 The Authors. Journal of Polymer Science Part B: Polymer Physics published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 454–464     

4-PICOLINE-o-DINITROBENZENE; A GENERAL CHROMOGENIC REAGENT FOR LOCATION OF ORGANOPHOSPHORUS PESTICIDES ON THIN-LAYER CHROMATOGRAMS

Abstract

A new general chromogenic reagent for location of organophosphorus pesticides and some of their breakdown products on thin-layer chromatograms has been developed. Chromatoplates are sprayed with 4-picoline and heated for 20 minutes at 100°C in an oven. After cooling, they are sprayed first with o-dinitrobenzene then with alkali. Pesticide spots appear blue in color.     

Influence of ignition condition on the growth of silicon thin films using plasma enhanced chemical vapour deposition

The influences of the plasma ignition condition in plasma enhanced chemical vapour deposition (PECVD) on the interfaces and the microstructures of hydrogenated microcrystalline Si (μc-Si:H) thin films are investigated.The plasma ignition condition is modified by varying the ratio of SiH 4 to H 2 (R H).For plasma ignited with a constant gas ratio,the time-resolved optical emission spectroscopy presents a low value of the emission intensity ratio of Hα to SiH (I Hα /I SiH) at the initial stage,which leads to a thick amorphous incubation layer.For the ignition condition with a profiling R H,the higher I Hα /I SiH values are realized.By optimizing the R H modulation,a uniform crystallinity along the growth direction and a denser μc-Si:H film can be obtained.However,an excessively high I Hα /I SiH may damage the interface properties,which is indicated by capacitance-voltage (C-V) measurements.Well controlling the ignition condition is critically important for the applications of Si thin films.     

磷酸铵镁结石患者尿微晶组分分析及其与结石形成的关系

采用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、纳米粒度仪、扫描电子显微镜(SEM)和透射电子显微镜(TEM)研究了磷酸铵镁结石患者尿液中微晶的组分、形貌、粒径和Zeta电位,并对其结石进行了组分分析.结果表明,结石类型、尿微晶组分和尿液pH三者之间存在密切的联系:磷酸铵镁结石病人的尿液pH值较高,通常在6....     

射频激发热丝化学气相沉积制备硅薄膜过程中光发射谱的研究

采用射频(rf)激发,在热丝化学气相沉积(HWCVD)制备微晶硅薄膜的过程中产生发光基元,测量了rf激发HWCVD (rf-HWCVD)的光发射谱,比较了相同工艺条件下rf-HWCVD和等离子体增强CVD(PECVD)的光发射谱,分析了rf功率、热丝温度和沉积气压对rf-HWCVD光发射谱的影响.结果表明,在射频功率<0.1W/cm²时,rf-HWCVD发射光谱反映了HWCVD高的气体分解效率和高浓度原子氢的特点,能够解释气压变化与微晶硅薄膜微结构的关系,是研究HWCVD气相过程的有 关键词： HWCVD OES 微晶硅     

Monitoring of the growth of microcrystalline silicon by plasma‐enhanced chemical vapor deposition using in‐situ Raman spectroscopy

Raman spectra of microcrystalline silicon layers have been recorded in‐situ during growth. The spectra have been collected under realistic conditions for solar cell deposition. To enable these measurements an electrode with an optical feed through has been developed. By using a metallic grid to shield the feed through it is possible to achieve homogeneous deposition of µc‐Si:H at a sufficient optical transmission. In‐situ Raman measurements were carried out during the deposition of a layer with an intentionally introduced gradient in crystallinity that was seen in‐situ as well in reference measurements performed on the same layer ex‐situ. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

VHF-PECVD低温制备微晶硅薄膜的拉曼散射光谱和光发射谱研究

采用拉曼散射光谱和PR650光谱光度计对VHF-PECVD制备的微晶硅薄膜进行了结构表征和在线监测研究.结果表明：功率对材料的晶化率（χc）有一定的调节作用，硅烷浓度大，微调作用更明显；SiH*的强度只能在一定的范围内表征材料的沉积速率，功率大相应的速率反而下降；I［Hα*］/I［SiH*］强度比值反映了材料晶化程度，此结果和拉曼散射光谱测试结果显示出一致性；I［Hβ*］/I［Hα*］的强度比表明氢等离子体中的电子温度随功率的增大而逐渐降低. 关键词： 甚高频等离子体增强化学气相沉积 微晶硅 拉曼散射谱 光发射谱