Low Voltage Contrast with an SEM Transmission Electron Detector

The images obtained with a transmission electron detector in low voltage SEM show an evolution of the well known dark field and bright field contrast with the accelerating voltage. Monte Carlo simulations explain these contrasts by the evolution of the electron scattering angle and stopping power of the thin foil with the accelerating voltage.     

Voltammetric behavior and ion chromatographic detection of nitrite at a dispersed platinum glassy carbon electrode

Cyclic voltammetry was used to investigate the electrochemical behavior of nitrite at a platinum-modified glassy carbon electrode (Pt-CME) in phosphate buffer (pH 4.5). Experiments in flow injection analysis and ion-chromatography (IC) were performed to characterize the electrode as an amperometric sensor for the determination of nitrite ions. The effects of several common interferences on the amperometric signal were estimated. The electrode stability, precision, limit of detection, and linear range were evaluated at a constant applied potential of 1.1 V. Calibration plots were linear from 0.03 μM to 0.5 mM with a slope of about 21 μA/mM and a correlation coefficient of 0.9987. The limit of detection (LOD) was 15 nM (0.7 ppb) in a 100 μL injection. The electrode response was sufficiently stable: over 6 h of operating time a 2.8% signal loss was observed. The determination of nitrite in milk and pear juices was achieved by IC and the relevant results were compared with those obtained with a standard spectrophotometric method.     

双束质子辐照砷化镓光电导探测器的I-V特性

 对用能量为7.5MeV和20MeV,注量为10¹¹～10¹³cm^-2的质子辐照后的砷化镓材料制作的光电导探测器的光电流和暗电流进行了测试，并由此推得电导率的变化。结果表明，经过能量为7.5MeV的质子改性后的砷化镓探测器相对于未改性的附加光电导率Δσ减少，而且随着辐照注量的增加而越小，而对于先用能量为20MeV质子辐照后再用能量为7.5MeV的质子辐照的砷化镓材料制作的探测器，其附加光电导率Δσ的减少则更为明显。对上述现象进行了分析，并根据其相应关系预测了该种探测器的响应时间、灵敏度、拖尾现象及受X射线激发的输出脉冲的后延的变化情况。     

3.8μm激光破坏三元PC型HgCdTe探测器系统的实验研究

 对3.8μm激光破坏三元PC型HgCdTe探测器系统的实验结果进行定性分析。实验结果表明：当辐照在探测器系统上的激光功率密度达411W/cm²时，系统内各部件（Ge窗口、滤光片及探测器）已严重损坏，探测器系统永久失效。分析认为：实验中引起探测器系统破坏的主要原因是温度升高引起的烧蚀热。     

Preparation of AgBr-detectors doped by some chemical elements Bi, Mn, Zn, Sn, Hg, Ca, Al, Ba, Cd and its sensitivity determination

One of the possible methods of increasing the sensitivity of track Aghal detectors by replacement of AgCl with AgBr is presented.     

毛细管气相色谱负压热导检测器及其应用

根据对负压下热导检测器的响应特性与检测器参数的系统研究，研制出适用于程序升温毛细管气相色谱的热导检测器（ＴＣＤ）。它的最小等效池体积为１．３μｌ，线性动态范围４个数量级，响应速度≤０．１ｓ，对丁烷的最小敏感浓度为０．００５％（Ｖ／Ｖ）。内径≥０．２５ｍｍ的各类毛细管柱可直接与检测器连接而不需用尾吹气。所设计的毛细管色谱进样装置，能在程序升温条件下保证流经分析柱的流量恒定、分流比恒定。解决了程序升温     

微波等离子体离子化检测器的应用研究—苯乙烯中乙苯的测定

微波等离子体是一种良好的激发光源和离子化源,可应用在气相色谱法中作通用或选择性检测器。其中表面波激发微波诱导等离子体离子化检测器(MIPID)对于挥发性有机物具有较好灵敏度,并且对某些永久性气体也有很好的响应。我们在完成MIPID检测器对有机和无机物响应特性研究的基础上,为了进一步考察这种MIPID检测器的可靠性和     

Detector for particulate polycyclic aromatic hydrocarbons in water

It is estimated that most polycyclic aromatic hydrocarbons (PAHs) in environmental water are not dissolved but rather in particulate form. Nevertheless, the currently available optical detectors are not suited for proper sampling of solid PAHs. A new setup for direct sampling and quantification of suspended particulate PAHs in water is suggested. It is based on a polymeric film that has the capability of dissolving PAH particulates, coupled to a traditional laser-induced fluorescence probe. Kinetics and performance of two sampling modes have been studied: bulk sampling, by immersing the probe into the water, and surface sampling, by laying the film on the water surface. The latter method has proved to be more sensitive; however, it is diffusion-limited. Linear calibration plots have provided quantification over a wide concentration range with detection limits in the ppb range (these could be improved by using a modified probe). The effects due to other particulates in water have been studied and only little interferences have been observed. The possibility of analysis of PAH mixtures has been addressed and it has been concluded that multivariate analysis is needed.