MAT261质谱计二次电子倍增器歧视效应研究和计数法建立

热表面电离质谱计(TIMS)MAT261在采用二次电子倍增器(SEM)接收时,SEM积分模拟模式的测量存在质量歧视效应和强度歧视效应.本研究测量了其质量歧视校正因子,建立了强度歧视效应基本可以忽略的测量方法.为实现弱信号的准确测量,建立SEM离子计数测量模式.基于SEM离子计数测量技术,应用钚标样比较SEM积分模拟模式...     

用于放射性气溶胶在线富集进样的狭缝虚拟撞击器的研制

为满足环境气溶胶在线进样的要求,改善电感耦合等离子体质谱计(Inductively Coupled Plasma Mass Spectrometry,ICP蛳MS)对粒子中待测核素的探测限,研制出一套具有低流量、低压降特点的狭缝虚拟撞击器,可作为气溶胶在线富集进样系统的关键部件与ICPˉMS联用。本文介绍了该狭缝虚拟撞击器的研制情况:首先由ICP蛳MS的进样条件,根据经验公式完成了理论设计,确定进样流量为11L/min,强流与弱流的流量比为10,喷射狭缝宽度为1mm,长宽比为10;然后用计算流体动力学软件Fluent R对上述结构内部的流场和粒子运动径迹进行了数值模拟,考察了喷射狭缝与收集狭缝的间距G、收集狭缝的宽度Wc及其进口曲率半径的加工偏差对收集效率的影响,得到了较优化的取值范围:G取1.0～1.2mm,Wc取1.4～1.6mm,此时的切割粒径D50约2.5μm;加工出狭缝虚拟撞击器的原型装置,对其分别用室内空气气溶胶和荧光素钠标记的单分散油酸粒子进行富集性能测量。实测结果表明:空气动力学等效直径在2.5～5μm范围内的粒子浓度得到了明显富集,5μm的粒子的富集因子达到极大值7。     

MAT261热表面电离质谱计测量数据不确定度评定

测量不确定度是与测量结果相关联的参数,表征合理赋予被测量之值的分散性.国际标准化组织(ISO)于1995年发布了<测量不确定度表示导则>,并在国际上广泛推广.我国于1999年发布了不确定评定的相关规范[1,2],并在全国推广应用.MAT261热表面电离质谱计具有高精度和高灵敏度的特征,应用较为广泛.本工作拟研究采用MAT261热表面电离质谱计测量铀同位素丰度比数据的不确定评定问题.     

三光子逐步激光共振电离质谱测定镥同位素比值

本文通过速率方程数值模拟计算和实验相结合的方法 ,研究各种激光参数对镥同位素激光诱导同位素歧视效应的影响。激光诱导同位素歧视效应主要来源于激光第二步跃迁几率的差异 ,本研究提出了减少和消除这一效应的方法。利用这一方法 ,对天然镥样品同位素比值进行测定 ,结果表明该方法可以减少LRIMS同位素分析中激光诱导同位素歧视的影响     

提高钚同位素质谱分析灵敏度的技术——活性炭粒法

本文叙述了一种提高钚离子发射的技术。将活性炭烧结在铼带上,钚样品溶液滴在炭粒上,可使质谱分析灵敏度提高一个数量级以上,有效地改善了钚同位素分析精度。在改进的ZhT-1301质谱计上灵敏度可达1离子/60原子,可分析0.1—20毫微克钚的同位素组成。     

热表面电离质谱法测量钚同位素

The plutonium isotopic abundance ratio was analyzed by thermal ionization mass spectrometry (TIMS) with the ion counting technique. The ion counting system was developed and applied by our lab teem on the MAT261. It is verified with the certificated isotopic reference material. Using 3×10^－9 g of plutonium, the combined standard uncertainty of ratio of ²⁴⁰Pu to ²³⁹Pu plutonium isotopes in 3 ng is 0.070%.     

电感耦合等离子体质谱质量分馏效应产生机理研究

Mass discrimination mostly is an obstacle to accurate determination of inductively coupled plasma mass spectrometry (ICP-MS). It is the prevailing notion that mass bias in ICP-MS results from space-charge effects of high density ions form the behind of skimmer cone to the before of slot where a fraction of lighter isotopes fail to enter the mass analyzer. Neodymium isotopes was analyzed by a Nu Plasma multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) to investigate the mass discrimination, respectively changing two crucial analytical parameters: the nebulizer flow and the x-coordinate of inductively coupled plasma, measuring the variety of the Ar40Ar40 molecular ions intensity and the exponential factor of mass discrimination. The curves indicate the presence of the secondly mechanism that lead to the heavier isotope depletion. It is maybe the plasma centrifuge effects, a concept proposed firstly by Qing-zhu Yin and Cin-Ty Lee. The two contrary mechanisms act on the ions and in theory the points should be exist where the two forces are equilibrium and the measurement results are the expectation values.     

ICP-MS实时监测气溶胶技术研究——气溶胶粒子的计数效率和单粒子中铽的探测效率

Study on real-time chemical analysis of aerosol particles with ICP-MS is conducting in our laboratory. Two key parameters are presented in this paper: counting efficiency of nanoparticle and mass detection efficiency of Tb in individual particles. Particles number counted by ICP-MS was compared with reading of Condensation Particle Counter Model 3010. Result shows that particle counting efficiency of ICP-MS is approximate unity. Monodisperse Tb(NO₃)₃•6H₂O particles with diameters of submicron to micron were generated and the diameter was obtained with Laser Particle Sizer and Nano-MOUDI respectively. Meanwhile the particle was introduced directly into ICP-MS to determine ions of ¹⁵⁹Tb. Result shows that response of ICP-MS for Tb in individual particle is rough linear with mass and detection limit could be down to 2.6 fg.     

同质异位素干扰下同位素比的ETV-ICP-MS测定

A self-made electrothermal vaporization (ETV) device was used to solve the isobaric interference in the isotope ratio analysis by ICP-MS. As a sampling method used in ICP-MS, ETV was used about twenty years and performed many merits. One of these merits is that it can separate the matrix of sample online according to the different evaporation rate of different element or compound on the filament of ETV. By this character, the isotope ratio of ¹⁷⁶Lu/¹⁷⁵Lu , as a example, was determined under the isobaric interference of ¹⁷⁶Yb by ETV-ICP-MS .     

气载、液载颗粒物直接进样ICP-MS技术及其在核工业中的应用

颗粒物分析在核、环境、生命科学等领域具有重要价值,不经复杂化学处理直接将颗粒物引入高灵敏电感耦合等离子体质谱（ICP-MS）分析,具有分析速度快、可获取单颗粒特征信息、化学处理工作量小等优势。本文综述了气载、液载颗粒物直接进样ICP-MS分析技术,介绍了该技术在高效过滤器下游复杂基体气溶胶样品中的超痕量钚检测和悬浮液中单个氧化铒颗粒的高精度同位素分析中的应用,并从技术发展和分析应用角度进行了展望。