校准质谱法准确测定锂同位素丰度

锂的同位素有六种：^5Li、^6Li、^7Li、^8Li、^9Li、^11Li,其中^6Li与^7Li为稳定同位素,^6Li在自然界中的丰度为7．42,^7Li为92．58。锂在工业、生物医学、地质、矿产、原子能工业等领域有着广泛的用途和重要作用,因此它的同位素丰度精密测定就显得十分重要。     

用校正质谱法测量铕同位素丰度的研究

用确定化学纯度的151Eu、153Eu两种浓缩同位素配成9个混合样品，用来测量质谱计系统误差的校正系数，以校正用该仪器测出的矿样和试剂样中铕同位素丰度比，求出铕同位素丰度的绝对值分别是47．810（42）at．％151Eu和52．190（42）at．％153Eu。用该值和已知的铕的核素质量，计算得到铕的原子量为151．9644（9），被定为新的国际标准值。     

高分辨等离子体质谱法测定锂同位素丰度的方法研究

在核燃料中,锂同位素丰度是重要的检测对象。近十多年来,快速发展起来的ICP-MS技术具有分析速度快,成本低,灵敏度高等优点,已应用核材料中铀、铅等同位素测定。本文研究了高分辨等离子体质谱(HR-ICP-MS)测定锂同位素丰度的技术方法,测定了纯锂化合物中锂同位素丰度。     

离子流强度累计法测定锂同位素丰度

本文介绍了离子流强度累计测定同位素比的方法。用热表面离子源测定了锂同位素丰度,在样品全耗尽过程中累计离子流强度。用该方法,同位素分馏效应对丰度比测量结果几乎没有影响。文中比较了累计法与常规法测量锂同位素丰度时分馏效应的差异。     

低丰度同位素质谱分析法

本文叙述低丰度同位素质谱分析法的理论基础、提高丰度灵敏度的途径以及测量技术的进展。     

锑,铕,铈,铒同位素丰度和原子量测量

用已知化学纯度的两种浓缩同位素通过化学计量,配制人工合成样品,用来测量质谱计系统误差校正系数,校正用该仪器测量的来自地球不同地域矿样和试剂样品中锑（Ｓｂ）、铕（Ｅｕ）、铈（Ｃｅ）、铒（Ｅｒ）四种元素天然同位素丰度比,求出这些元素同位素丰度的真值。用该真值和已知的上述四元素核素质量,计算得原子量分别为１２１．７５９７（７）Ｓｂ、１５１．９６４４（９）Ｅｕ、１４０．１１５７（８）Ｃｅ、１６７．２５９１（９）Ｅｒ     

高粱中氮同位素丰度的测定和应用

为研究不同肥料对高粱中氮稳定同位素丰度的影响,采用稳定同位素质谱法测定高粱中氮同位素比值,并对有机和常规两种农业体系种植的高粱果实进行同位素分析。结果表明：高粱δ¹⁵N值与高粱生长过程中所施的肥料密切相关;施有机肥的高粱δ¹⁵N值普遍高于施化肥的高粱,因此δ¹⁵N值可作为鉴别有机高粱和常规高粱的重要参考要素。该方法可对有机高粱酿造的白酒和其他高粱酿造的白酒进行鉴别和区分,以维护企业和消费者的合法权益。     

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.     

锗原子量的新测定(英文)

用两种高富集锗同位素配制的标准混合溶液系列 ,以标定一台 MAT-2 62热电离质谱仪 ,求得 4个同位素丰度比的校准因数 ,从而测得 5种天然锗样品的 4个同位素丰度比的真值。由此计算天然锗 5种同位素的丰度值如下 :2 0 .37± 0 .0 5　　原子 %70 Ge2 7.38± 0 .0 4　　原子 %72 Ge7.76± 0 .0 5　　原子 %73 Ge36.66± 0 .0 5　　原子 %74 Ge7.83± 0 .0 5　　原子 %76Ge再各乘以已知的原子质量 ,得出锗原子量的新值为 :Ar( Ge) =72 .639± 0 .0 0 4这些精确数值的置信度为 95%。优于文献上所有已知的相应值。     

多接收电感耦合等离子体质谱法测量分离样品中Li同位素丰度比

Isotopic abundance ratios in chemical exchange separation sample were determined using GV IsoProbe multicollector-inductively coupled plasma mass spectrometry (MC-ICP-MS). GV IsoProbe MC-ICP-MS was calibrated by the lithium nature isotope reference material. Calibrated GV IsoProbe MC-ICP-MS was used to determine lithium isotope abundance ratio which was produced through chemical change separation.     

氢氘化锂氘丰度质谱分析技术研究

本文介绍了用低分辨MAT -2 50气体质谱计准确测定氢氘化锂中氘丰度的分析技术。结果表明 ,对不同氘丰度的气体样品 ,单次测定的相对标准偏差好于 0 2 % ,氘丰度测量值在 0 2 %的误差范围内是可信的     

金属铼带材料中的铼同位素组成和原子量

本文采用热电离质谱法精确测定了三种铼带材料中的铼同位素组成,平均~(185)Re/~(187)Re比值为0.59721±0.00008(2SD),由此计算得到铼的原子量为Ar(Re)=186.20693(6)     

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.     

镝原子量测量-热电离质谱法的应用

用已知化学纯度的 16 2 Dy、16 4Dy两种浓缩同位素通过化学计量 ,配制人工合成校准样品 ,测量质谱计系统误差校正系数 K,校正用该仪器测量的来自地球不同地域矿物和试剂样品镝 ( Dy)元素天然同位素丰度比 ,求出自然界 Dy同位素丰度的真值。用该真值和它的核素质量 ,计算 Dy原子量 1 62 .4 995 ( 1 7)。上述测量经 IUPAC国际原子量委员会 ( UPAC-CAWIA)评审确认推荐报告中提供的测量值为 Dy原子量新的国际标准值 ,测量方法评为最佳测量     

The role of mass spectrometry in atomic weight determinations

The 1914 Nobel Prize for Chemistry was awarded to Theodore Richards, whose work provided an insight into the history of the birth and evolution of matter as embedded in the atomic weights. However, the secret to unlocking the hieroglyphics contained in the atomic weights is revealed by a study of the relative abundances of the isotopes. A consistent set of internationally accepted atomic weights has been a goal of the scientific community for over a century. Atomic weights were originally determined by chemical stoichiometry--the so-called "Harvard Method," but this methodology has now been superseded by the "physical method," in which the isotopic composition and atomic masses of the isotopes comprising an element are used to calculate the atomic weight with far greater accuracy than before. The role of mass spectrometry in atomic weight determinations was initiated by the discovery of isotopes by Thomson, and established by the pioneering work of Aston, Dempster, and Nier using sophisticated mass spectrographs. The advent of the sector field mass spectrometer in 1947, revolutionized the application of mass spectrometry for both solids and gases to other fields of science including atomic weights. Subsequently, technological advances in mass spectrometry have enabled atomic masses to be determined with an accuracy better than one part in 10(7), whilst the absolute isotopic composition of many elements has been determined to produce accurate values of their atomic weights. Conversely, those same technological developments have revealed significant variations in the isotope abundances of many elements caused by a variety of physiochemical mechanisms in natural materials. Although these variations were initially seen as an impediment to the accuracy with which atomic weights could be determined, it was quickly realized that nature had provided a new tool to investigate physiochemical and biogeochemical mechanisms in nature, which could be exploited by precise and accurate isotopic measurements. Atomic weights can no longer be regarded as constants of nature, except for the monoisotopic elements whose atomic weights are determined solely by the relative atomic mass of that nuclide. Stable isotope geochemists developed mass spectrometric protocols by the adoption of internationally accepted reference materials for the light elements, to which measurements from various laboratories could be compared. Subsequently, a number of heavy elements such as iron, molybdenum and cadmium have been shown to exhibit isotope fractionation. The magnitude of such isotope fractionation in nature is less than for the light elements, but technological developments, such as multiple collector-inductively coupled plasma-mass spectrometry, have enabled such fractionation effects to be determined. Measurements of the atomic weights of certain elements affect the determination of important fundamental constants such as the Avogadro Constant, the Faraday Constant and the Universal Gas Constant. Heroic efforts have been made to refine the accuracy of the atomic weight of silicon, with the objective of replacing the SI standard of mass--the kilogram--with the Avogadro Constant. Improvements in these fundamental constants in turn affect the set of self-consistent values of other basic constants through a least-squares adjustment methodology. Absolute isotope abundances also enable the Solar System abundances of the s-, r-, and p-process of nucleosynthesis to be accurately determined, thus placing constraints on theories of heavy element nucleosynthesis. Future developments in the science of atomic weight determinations are also examined.