VG354质谱计软件系统的改进及功能扩展

根据同位素测这新方法的建立和石墨的非还原离子发射特性等方面研究的需要,在现有VG354质谱计的软件系统功能基础上,改进并开发了该正热电离质谱计的测量新功能。该新增功能依据被测样品设定的初始值,采用峰跳扫描方式自动连续测量随时间的变化一种或几种正离子的离子流强度,同位素比值等数值的变化,同时可将结果输出到打印机或保存到磁盘中,为研究同位素分馏,离子的发射机理以及石墨的非还原离子发射特性等建立了良好的实验条件,并提供了准确可靠的实验数据。     

多接收电感耦合等离子体质谱法测量UTB系列铀同位素工作标准同位素比值

In order to analyze uranium isotopic ratios accurately by mass spectrometry, reference materials are used to correct the mass bias and detector bias. Isotopic ratios of UTB U Series working reference material which have been developed in our country last century were measured by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). In this report, the isotopic ratios were corrected by measuring CRM U series reference material. Hydride rate UH^＋/U⁺ of different sample introduction devices were studied. The linearity of the Daly detector was also investigated. Preliminary results have indicated that there is no significant difference between the measurement value and reference value.     

皮克量级钚同位素丰度比的TIMS分析

The isotopic abundance ratios for Pu at 6.7 pg level were measured by thermal surface ionization mass spectrometry (TIMS). During the preparation of Pu samples carbon power was used as an emitting and stabilizing reagent, which increase the collection efficiency, the ion current intense and the ion emission stability for Pu. The measurment results indicate that the relative standard deviation of 2.7% for the isotopic abundance ratios of 240Pu to 239Pu is achieved when the 240Pu ion current is 8-20 cps.     

表面热电离同位素稀释质谱法的计算及质量分馏效应校正

表面热电离同位素稀释质谱法(ID-TIMS)是国际公认的基准方法之一。本文以稀释分析锶同位素为例,详细介绍了其计算和推导过程,提出基于指数近似模式的稀释分析同位素分馏校正的方法。该方法适用于校正含有两对参考比值的元素静态多接收稀释分析同位素比值的质量分馏,与指数校正方法和对数校正方法相比,计算过程更简单。还讨论了稀释剂同位素比值准确度对稀释分析同位素比值的影响及其质量分馏的校正方法,通过数学迭代计算质量分馏系数,得到稀释剂测量的质量分馏系数和准确的同位素比值。采用建立的质量分馏校正方法稀释分析NBS987,结果表明,在误差范围内与其参考值（⁸⁷Sr/⁸⁶Sr=0.710237±8（1σ））一致。     

涂样量对纳克级硼同位素测定的影响

在石墨存在下 ,用正热电离质谱法 ,使用Cs2 BO2+离子测定了含 1 0 0、50、2 0ng和 1 0ngB的NISTSRM 951硼酸标样中的硼同位素的组成。结果表明 ,随着涂样量的减少 ,硼同位素丰度测定比值 ( 1 1 B/1 0 B)和测定精度有所下降。本文也给出了VG -3 54正热电离质谱测定纳克级硼同位素组成的最佳条件。结果表明 ,当涂样量大于 1 0 0ngB时 ,硼同位素丰度比的测量精度最佳 ,1 0ngB是正热电离质谱法使用法拉第杯检测硼同位素组成的最低限量。本研究为开展低硼含量的海洋微体古生物 ,古土壤 ,河水等地质样品中的硼同位素组成质谱测定提供了依据。     

超微量钐同位素丰度比的质谱测定

本文简介了使用Finnigan　MAT　262热电离质谱仪对超微量钐天然同位素丰度比的精密测定。每次控制样品含钐量小于100ng,重复测量结果的精度好于0.1％。     

U-Pb定年锆石标准~(176)Hf/~(177)Hf比值的多接收器电感耦合等离子体质谱测定

利用MicromassIsoprobe型多接收器电感耦合等离子体质谱(MCICPMS)测定UPb定年国际锆石标准91500、Temora和本实验室锆石工作标准样We1的176Hf/177Hf比值。对添加Zr的室内Hf标准溶液HfGIG的模拟实验表明:Zr/Hf≤120时,Zr对Isoprobe型MCICPMS的Hf同位素比值测定值没有明显的影响,所以锆石Hf分离纯化流程采用改进的高温高压氢氟酸溶解和其后的一个离子交换分离流程实现,整个流程Hf的回收率高于90%。176Hf/177Hf比值测定采用JMC475Hf标准溶液(176Hf/177Hf=0.282160)进行外部校正并监控仪器漂移。标准样91500、Temora和We1平均的176Hf/177Hf比值测定结果分别为(0.282310±0.000034)、(0.282706±0.000020)和(0.281534±0.000009)。上述每个结果包括至少7组独立的锆石样品的溶解、分离和测定,表明标准样91500、Temora和We1是Hf同位素组成均一的。本实验结果对于激光熔蚀多接收器电感耦合等离子体质谱(LAMCICPMS)锆石原位176Hf/177Hf比值测定校正方法的检验具有重要意义。     

同位素丰度绝对测量及相对原子质量测定中的不确定度评估

The sources of uncertainty of relative atomic mass include measurement errors and isotopic fractionation of terrestrial samples. Measurement errors are composed of measurements of atomic masses and isotopic abundances, the later includes uncertainty of correction factor K and isotopic ratios of natural samples. Through differential of seven factors to gain their propagation factors, the uncertainty of correction factors K can be calculated. With the same differential calculation, the uncertainty of relative atomic mass can be obtained.     

SIMS分析含铀微粒同位素比测量条件的初步研究

The isotope ratios of uranium in particles were closely related to the activities performed in nuclear facilities where the particles were collected, so that the determination of ratio is very important in environmental sample analysis for nuclear safeguards. The method based on the use of secondary ion mass spectrometry (SIMS) was presented for the determination of uranium isotopic composition. The parameters of SIMS were studied in the paper, such as contrast aperture(CA)、lence4(L4)、image field(IF)、the accelerated voltage of primary ions and the secondary ions and so on. These parameters are optimized by measuring the standard reference uranium materials (CRM005 CRM200) for improving the measurement accuracy and the precision of uranium isotopic ratio.     

新一代高分辨多接收双聚焦等离子质谱

为了克服元素分析过程中质谱的干扰和提高同位素比测量的精度,高分辨多接收双聚焦等离子质谱已成为有效的手段。本文介绍了新一代VG Axiom高分辨多接收等离子质谱设计特点、实际测量的技术性能及其在分析上典型的应用。     

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     

同位素质谱和无机质谱在化学计量中的应用进展

This report summarizes the application and development of isotopic and inorganic mass spectrometries in chemical metrology. Isotopic and inorganic mass spectrometries play an important role in chemical metrology. They are applied in determination of chemical standard data, such as atomic weights and isotopic abundances, and preparation of isotopic certified reference materials and spikes. Absolute determination method of isotopic abundances and isotopic dilution mass spectrometry method have the metrological characteristic, which have being used in research of chemical metrology.     

Interstellar dust laser explorer: a new instrument for elemental and isotopic analysis and imaging of interstellar and interplanetary dust

We present the performance characteristics of a time-of-flight secondary ion mass spectrometer designed for 157 nm laser postionization of sputtered neutrals for high sensitivity elemental and isotopic analyses. The instrument was built with the aim of analyzing rare element abundances in micron to submicron samples such as interstellar grains and cometary dust. Relative sensitivity factors have been determined for secondary ion mass spectrometry which show an exponential dependency against the first ionization potential. This allows elemental abundances to be measured with errors below 25% for most major elements. The accuracy for isotope ratios, where isotopes can be resolved from isobaric interferences, is usually limited only by counting statistics. In laser secondary neutral mass spectrometry, the spatial and temporal overlaps between the laser and sputtered neutral atoms are modeled and predictions of total detection efficiency and isotopic and elemental fractionation are compared with experimental data. Relative sensitivity factors for laser-ionized secondary neutrals from a stainless steel standard are found to vary less than 3% above saturation laser pulse energy enabling more accurate quantification.     

同位素标准物质量值不确定度的表达

〕本文给出了同位素标准物质研制中不确定度的表达公式,讨论了原料富集情况、质谱测量、同位素标准物质预期丰度等因素的影响,并对所述方法进行了应用举例     

痕量铱同位素的负离子质谱分析方法研究

铱（Ir）同位素组成可作为理想的核燃料燃耗指示信息。提高Ir待测离子的电离效率,以获得足够强度且稳定的离子流是精确测量痕量Ir同位素组成的关键。因Ir电离电位较高,极难形成稳定的正离子,因此需采用负离子模式。本研究通过对比不同的灯丝材料、灯丝结构、涂样条件、电离温度等因素,建立并优化了Ir的负离子转化条件。通过采用Pt单带、Ba(OH)₂为发射剂涂样,并缓慢提高灯丝电流,50 ng的Ir电离效率可达9.8×10^-4。经氧同位素校正后,Ir涂样量10 ng以上的n(¹⁹¹Ir)/n(¹⁹³Ir)同位素比值与标准溶液的参考值在误差范围内一致,且相对标准偏差优于0.2%,能够满足痕量Ir同位素组成的测量精度要求。     

RPQ-IC检测系统测量低丰度铀同位素

介绍了采用 Finnigan MAT 2 62热电离质谱计检测 NBS U 0 1 0、浓缩 2 3 3 U硝酸溶液 ( IRMM-0 40 a)。采用阻滞电位四极杆 ( RPQ) -IC装置测量低丰度铀 2 3 4 U、2 3 5U、2 3 6U的同位素丰度比 ,并与 Faraday(法拉第杯 )检测的数据进行比较。采用偏转法对 RPQ产额进行了校正。实验表明 :所得结果在误差范围内 ,RPQ-IC测量结果比 RPQ-FAR测量结果偏高 0 .1 4% ;RPQ-IC测量低丰度铀同位素的内精度比法拉第杯测量结果高 ,外精度比 FAR杯测量结果也高 ;RPQ产额变化比较大 ,但只要注意产额校正 ,可以得到满意的结果     

Mass spectrometry and isotopes: a century of research and discussion

In 1815, the British physician William Prout had advanced the theory that the molecular masses of elements were multiples of the mass of hydrogen. This "whole number rule" (and especially deviations from it) played an important role in the discussion whether elements could be mixtures of isotopes. F. Soddy's discovery (1910) that lead obtained by decay of uranium and of thorium differed in mass was considered a peculiarity of radioactive materials. The question of the existence of isotopes came up when the instruments developed by J.J. Thomson and by W. Wien to study cathode and canal rays by deflection in electric and magnetic fields were steadily improved. In 1913, Thomson mentioned a weak line at mass 22 accompanying the expected one at mass 20 when he analyzed the mass spectrum of neon. Subsequently Aston obtained the mass spectrum of chlorine with masses at 35 and 37. Still in 1921, Thomson objected heavily to the idea of isotopes. The isotope problem was finally settled, but more accurate mass measurements showed that even isotopic weights differed to some extent from the whole numbers. Based on earlier ideas of P. Langevin and J.-L. Costa, F.W. Aston and A.J. Dempster developed the idea of packing fractions and mass defects due to the transformation of a portion of the matter comprising the atomic nucleus into energy. While the determination of the exact isotopic masses had improved over the years, the accurate determination of isotopic abundances remained a problem as long as photographic recording was used. Here especially A.O. Nier pioneered using dual collectors and compensation measurements. This was the prerequisite for the discovery that isotopic ratios varied somewhat in nature. M. Dole discovered the fractionation of oxygen isotopes by photosynthesis and respiration. Today 13C/12C-ratios are employed to detect adulterations of food and in doping analysis, and 14C/13C-ratios obtained by accelerator mass spectrometry are used for dating historical objects, just to give some examples.     

同位素比值质谱法测定TNT的来源

炸药的来源鉴别在犯罪案件尤其是爆炸案件的侦查有着重要的价值。本文首次报导利用同位素比值质谱法对四个不同厂家的 TNT,即硝铵炸药的主成份 ,进行 13C和 15N的同位素比值测定。初步的结果表明 ,( 1 )根据它们的同位素比值 ,可以区分这四个厂家的 TNT;( 2 )样品用量低于 1微克 ;( 3)利用 EA和GC二种进样方式 ,获得了平行一致的数据 ;( 4 ) 13C的测定精度± 0 .2 0‰ ,15N为± 0 .40～ 0 .50‰。     

MC-ICP-MS测量Ru同位素丰度比值的质量歧视校正

采用MC-ICP-MS测量Ru同位素丰度比时,存在较大的质量偏倚。利用IsoprobeMC-ICP-MS测量了RuCl3中Ru同位素丰度比值,并利用幂、指数以及通用幂校正规律(GPL)对Ru同位素丰度比值测量的质量偏倚进行了校正。结果表明,以100Ru/102Ru、104Ru/102Ru作为内标,采用GPL校正质量偏倚,得到的Ru同位素丰度更接近于天然值,与天然值的偏差在(20～650)×10-6之间。     

多接收双聚焦等离子体质谱法测定高精度同位素比

采用 VG Axiom型多接收双聚焦等离子质谱仪 ( MC-ICPMS)测定 Nd、Pb、U同位素比值 ,应用指数公式对测定的结果进行质量歧视校正。结果表明 :测定参考物质 Ames Nd获得的钕同位素比值为 14 3 Nd/14 4 Nd=0 .5 1 2 1 44± 0 .0 0 0 0 1 5 (确认值为 0 .5 1 2 1 3 5 )、14 5Nd/14 4 Nd=0 .3 4841 7± 0 .0 0 0 0 1 9(确认值为 0 .3 4841 8) ;测定参考物质 NIST SRM981获得的铅同位素比值为 2 0 8Pb/2 0 4Pb=3 6.71 1 4± 0 .0 0 81、2 0 7Pb/2 0 4Pb=1 5 .4886± 0 .0 0 3 8、2 0 7Pb/2 0 6Pb=0 .91 44 5 6± 0 .0 0 0 0 3 9、2 0 6Pb/2 0 4Pb=1 6.93 82± 0 .0 0 3 1、2 0 8Pb/2 0 6Pb=2 .1 660 1± 0 .0 0 0 1 6;测定参考物质 NIST SRM 0 1 0获得的铀同位素比值为 2 3 4 U/2 3 8U =0 .0 0 0 0 5 46±0 .0 0 0 0 0 0 3 (确认值为 0 .0 0 0 0 5 46)