碰撞池-多接收电感耦合等离子体质谱测定硒同位素的质量偏移效应

通过改变雾化气流量、RF射频发生器功率、矩管位置和碰撞气流量等仪器参数,研究了碰撞池-多接收电感耦合等离子体质谱(Collision Cell-MC-ICP-MS)中的质量偏移效应。实验结果表明,雾化气流量、RF发生器功率和矩管位置等是质量偏移效应的主要来源,而碰撞气流量的影响很小。在此基础上,建立了MC-ICP-MS分析硒同位素丰度的最优化测量条件,同位素比R82/76的测量精度达到0.0043%。采用化学计量方法配制了两个系列硒同位素丰度校正样品,通过不同的同位素丰度比的质量偏移校正因子β和与其对应的同位素对的质量平均值成线性的关系,分析了样品GBW(E)080215和SRM3149中硒的同位素丰度组成。与样品SRM3149中82Se/76Se的比值相比,样品GBW(E)080215中的硒同位素分馏系数δ82/76为-4.78‰。     

电感耦合等离子体原子发射光谱(ICP-AES)法测定Ti50Si合金中的钛元素

研究了ICP-AES测定Ti50Si合金中钛含量的方法。采用氢氟酸、硝酸溶解试样,优化了射频发生器(RF)功率、雾化压力、辅助气流量以及泵速等仪器参数,通过实验分析了溶液酸度、分析谱线的影响,确定了最佳实验条件。测定了2份Ti50Si样品,相对标准偏差小于0.64%(n=11),与硫酸高铁铵滴定法测定结果一致,证明了方法有较高的准确度和实用性。     

电感耦合等离子体光谱(ICP-AES)法测定Ti50Si合金中的钛元素

研究了ICP-AES测定Ti50Si合金中钛含量的方法。采用氢氟酸、硝酸溶解试样,优化了射频发生器(RF)功率、雾化压力、辅助气流量以及泵速等仪器参数,通过实验分析了溶液酸度、分析谱线的影响,确定了最佳试验条件。采用此方法测定了2份Ti50Si样品,相对标准偏差小于0.64%(n=11),与硫酸高铁铵滴定法测定结果一致,证明了该方法有较高的准确度和实用性。     

一种安全的气体燃烧装置

做一些气体如氢气、一氧化碳的可燃性实验,直接在气体发生器的导气管外端点火,学生、老师存在有恐惧感,担心万一反应器内有空气存在,火焰进入其中而发生爆炸(即使已作气体试纯试验,这种担心仍依然存在).为了消除师生的这种恐惧心理,也是为了使实验万无一失,我们设计了一种极其简单的、安全的气体燃烧装置.     

微型ICP激发源对液体样品中砷与汞的定性分析

将自制微型ICP激发源与氢化物发生器组成实验平台,对溶液中的砷、汞进行了定性分析探索,解决了自制的微型ICP激发源无法测试液体样品的问题。采用硼氢化钠-盐酸体系在氢化物发生器中运用气动型断续流动发生法制取含砷、汞的氢化物气体样品。利用高纯氩作为载气将收集到的样品气体送入微型ICP激发源放电室,在RF功率为12 W,气压为70 Pa的工作条件下起燃后检测到光谱信号,利用Sepcline软件辨识出2条砷(211.30,234.98nm)元素谱线、2条汞(296.73,313.15 nm)元素谱线。实验分析得出了砷、汞检测所用盐酸和硼氢化钠的最佳配比。采用自制微型ICP激发源检测到砷、汞谱线,该激发源可用于液体砷汞样品的定性检测。     

氢化物发生-电感耦合等离子体质谱联用技术研究

运用自制的接口，实现了氢化物发生与电感耦合等离子体质谱的联用。考察了连续流动氢化物发生器、气动型断流式氢化物发生器及气动型流动注射氢化物发生器与电感耦合等离子体质谱仪的联用性能。确定了仪器的最佳参数，研究了系统的分析性能，实现了能生成氢化物的8种元素的定量测定。     

基于H2O2的自燃离子液体研究进展

基于H₂O₂的自燃离子液体是目前绿色自燃推进剂领域的一个重要研究方向。本文对H₂O₂—离子液体的自燃体系进行了综述，富B-H类和硫氰酸阴离子类离子液体能与H₂O₂直接自燃，在加入碘铜酸盐等促进剂后达到更好的点火效果；此外二氰胺根阴离子类、二甲基硼磷酸根阴离子类和醋酸根阴离子类等离子液体不能与H₂O₂直接自燃，但加入促进剂后能达到良好点火效果。进一步介绍了各类自燃离子液体的合成方法和理化性质，提出基于H₂O₂—离子液体自燃推进剂的研究重点应着眼于以下三方面：更高能量密度离子液体的设计合成、高活性促进剂的研制开发以及强化点火的内在机制。     

用水合五氧化二锑分离放射性母子体的研究─—一个新的~(201)Pb—~(201)T1发生器的制备

本文研究了无机离子交换剂—水合五氧化二锑（Sb2O5·nH2O）的制备，并用它分离了放射性母子体，制备了一个新的201Pb—201Tl放射性发生器。结果表明，末发生器具有高效、快速、简便的特点，此外还讨论了离子交换反应的机理。     

分流式湿度发生器温度控制系统的设计

采用控制加热的方法对分流式湿度发生器的增湿饱和器进行精密的温度控制。介绍了增湿饱和器的结构及温度控制电路、温度控制软件的设计要点。通过精密控制增湿饱和器的温度，减少了环境温度变化对分流式湿度发生器输出湿度的影响，提高了湿度校准的准确度。     

激光诱导击穿光谱对U元素的定量分析

铀矿是核领域最重要的矿产资源之一，快速、有效勘探铀矿资源能促进核领域平稳、健康发展。激光诱导击穿光谱(LIBS)技术具备多目标元素现场快速检测的优点，能实现铀矿资源准确、快速的现场分析。本工作基于LIBS技术对铀矿中U元素进行了定量分析，对比了偏最小二乘(PLS)和随机森林(RF)两种机器学习算法的定量效果。结果显示，RF模型的定量线性相关系数为0.996，对三个验证集的相对误差分别是22.33%、12.79%和12.04%；PLS模型的定量线性相关系数为0.997，对三个验证集的相对误差分别是4.33%、6.63%和6.85%。对比结果表明，本研究中的PLS模型定量准确度更高，同RF算法相比，PLS算法更适用于铀矿中U的LIBS定量分析。     

Multiple criticality and staged ignition of methane in the counterflow

The counterflow ignition of methane was investigated, with particular interest in the role of radical versus thermal runaway. Simulation with different kinetic mechanisms showed that the ignition response is qualitatively sensitive to the kinetic mechanism adopted, either exhibiting or not exhibiting two ignition turning points in the S‐curve response. For the former situation, ignition could take place in a staged manner with either increasing temperature or decreasing strain rate of the counterflow, characterized by the first ignition event being radical induced with negligible thermal effect and the second ignition event requiring thermal feedback. Sensitivity analysis and a recently developed chemical explosive mode analysis were performed to identify the dominant reactions in the radical runaway stage, revealing the importance of branching pathways involving the HO₂ radical. Counterflow experiments were also conducted, yielding useful information on the ignition response. The study identifies items of further research to sharpen the comprehensiveness and accuracy of the methane oxidation mechanism. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 764–776, 2009     

飞行时间质谱仪四极杆射频信号放大器的研制

根据自制质谱仪需求研制了一种射频放大装置,由放大电路模块和耦合线圈构成,将其与射频信号发生装置结合用以驱动射频四极杆.该射频放大器可将射频信号放大30倍,为自制射频四极杆提供共振频率1.4 MHz,射频电压峰峰值电压Vp-p可调范围0～600 V的射频信号.自制四极杆用于传输大气压下离子源产生的离子从离子源至工作在高真...     

Optimization of technological parameters in plasma chemical etching of quartz single crystals

Main technological parameters of the process of local plasmochemical etching of single-crystal quartz were optimized. The etching was performed in a gas mixture of CF₄ and H₂ under radio frequency (RF, 13.56 MHz) discharge excitation. The scientific experiment design by the Taguchi matrix method was used to examine the effect of chamber pressure, RF generator power, negative bias applied to the substrate holder, and hydrogen flow rate on the rate of the etching process. The experimental results made it possible to evaluate for the first time the influence exerted by the technological parameters on the etching rate. It was shown that the influence exerted by the technological parameters in the conditions under study decreases in the following order: pressure in the reaction chamber, bias potential, RF power, hydrogen flow rate.     

Analysis of petrol and diesel vapour and vehicle engine exhaust gases using selected ion flow tube mass spectrometry

We have used selected ion flow tube mass spectrometry (SIFT-MS) to analyse the vapours emitted by petrol and diesel fuels and the exhaust gases from petrol (spark ignition) and diesel (compression ignition) engine vehicles fitted with catalytic converters. Only those components of these media that have significant vapour pressures at ambient temperatures were analysed and thus particulates were obviously not detected. These media have been analysed using the full scope of SIFT-MS, i.e., with the three available precursor ions H3O+, NO+ and O2+. The combination of the H3O+ and NO+ analyses is seen to be essential to distinguish between different product ions at the same mass-to-charge ratio (m/z) especially in identifying aldehydes in the exhaust gases. The O2+ precursor ions are used to detect and quantify the large amount of nitric oxide present in the exhaust gases from both engine types. The petrol and diesel vapours consist almost exclusively of aliphatic alkanes, alkenes and alkynes (and dienes) and aromatic hydrocarbons. Some of these compounds appear in the exhaust gases together with several aldehydes, viz. formaldehyde, acetaldehyde, pentanal, pentenal (acrolein), butenal, and also methanol and ethanol. Acetone, nitric oxide and ammonia are also present, acetone and nitric oxide being much more abundant in the diesel exhaust gas than in the petrol exhaust gas. These data were obtained from samples collected into pre-evacuated stainless steel vessels. Trapping of the volatile compounds from the gas samples is not required and analysis was completed a few minutes later. All the above compounds are detected simultaneously, which demonstrates the value of SIFT-MS in this area of research.     

Kinetic modelling of the oxidation of large aliphatic hydrocarbons using an automatic mechanism generation

A mechanism generator code to automatically generate mechanisms for the oxidation of large hydrocarbons has been successfully modified and considerably expanded in this work. The modification was through (1) improvement of the existing rules such as cyclic-ether reactions and aldehyde reactions, (2) inclusion of some additional rules to the code, such as ketone reactions, hydroperoxy cyclic-ether formations and additional reactions of alkenes, (3) inclusion of small oxygenates, produced by the code but not included in the handwritten C(1)-C(4) sub-mechanism yet, to the handwritten C(1)-C(4) sub-mechanism. In order to evaluate mechanisms generated by the code, simulations of observed results in different experimental environments have been carried out. Experimentally derived and numerically predicted ignition delays of n-heptane-air and n-decane-air mixtures in high-pressure shock tubes in a wide range of temperatures, pressures and equivalence ratios agree very well. Concentration profiles of the main products and intermediates of n-heptane and n-decane oxidation in jet-stirred reactors at a wide range of temperatures and equivalence ratios are generally well reproduced. In addition, the ignition delay times of different normal alkanes was numerically studied.     

BAIRD Ps-6真空型电感耦合等离子发射光谱仪的故障分析与对策

对Ｐｓ－６型光谱仪作了简介的基础上，从联锁保护电路入手，选择了射频发生器。相检测电路，气路，真空系统，光路准直监视系统，光电倍增管和高压电路等八例有代表性，。已排除的故障实例深入进行了研究，提出了排除故障的思路与办法。     

Electrical Features of Radio-frequency,Atmospheric-pressure,Bare-metallic-electrode Glow Discharges

Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas with bare metallic electrodes have promising prospects in the fields of plasma-aided etching, deposition, disinfection and sterilization, etc. In this paper, an induced gas discharge approach is proposed for obtaining the RF, atmospheric-pressure, γ-mode, glow discharges with pure nitrogen or air as the primary plasma-working gas using bare metallic electrodes. The discharge characteristics, including the discharge mode, the breakdown voltage and discharge voltage for sustaining α mode and/or γ mode discharges, of the RF APGD plasmas of helium, argon, nitrogen, air or their mixtures using a planar-type plasma generator are presented in this study. The uniformity (no filaments) of the discharges is confirmed by the images taken by an iCCD with a short exposure time (10 ns). The effects of different gap spacings and electrode materials on the discharge characteristics, the variations of the sheath thickness and the electron number density are also studied in this paper.     

沙尘天气对AAS、ICP-AES测定的影响

以大型仪器原子吸收光谱仪、电感耦合等离子体发射光谱仪为例,说明当沙尘天气发生时,空气中的粉尘和微小颗粒进入到仪器内部会引起空气压缩机故障、射频发生器的传感器不工作、助燃气堵塞等一系列问题;并针对这些问题进行处理,给以后仪器的使用和保养提供相应的参考。