RGA10质谱计的改进及在K-Ar、Ar-Ar同位素定年中的应用

对 RGA1 0质谱计离子源、分析室、样品提纯系统及数据处理系统等方面进行了改进 ,并增加了 3 8Ar大小球分取装置 ,使该仪器灵敏度、真空度及仪器的综合指标比过去有了较大改善 ,仪器的稳定性及测试样品的速度有了很大提高。仪器改造后三年来的实验证明 :Ar同位素的分析效率提高了 2至 3倍。     

A study of Ar + C2H4 and Xe + CF4 gas mixtures

Mixtures of Ar + 40 ppm C₂H₄ and 50% Xe + 50%CF₄ have been investigated. The spatial distributions of photoelectron clouds produced by primary scintillations on α- and β-particle tracks, as well as the distributions of photoelectron clouds due to photons from avalanches at the pin anode, have been measured for the first time. For a mixture of 50% Xe + 50%CF₄, it has been shown for the first time that CF₄ is a photosensitive dopant in a mixture with Xe. For a mixture of Xe + CF₄ (1: 1), the maximum electron multiplication factors at the pin anode are K(β)^max = 3 × 10⁴ and K(α)^max = 3 × 10³ at a pressure of 1 atm (abs.) and K(β)^max = 10⁴ and K(α)^max = 4 × 10³ at a pressure of 10 atm (abs.)     

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.     

高压模块性能对数字离子阱质谱仪性能的影响

数字线性离子阱质谱仪的供电高压模块的稳定度、负载变化率等参数对数字离子阱的性能有很大影响。为了研究供电高压模块对仪器性能的影响,本工作基于正在研制的便携式数字线性离子阱质谱仪,以1 mg/L苯、甲苯、二甲苯、氯苯混合标准气体为检测对象,研究高压模块性能改进后仪器性能的变化情况。结果表明：通过增加稳压模块的方法,使离子阱质谱仪一级质谱的质量稳定性、离子响应,二级质谱的隔离效率都有较大幅度的提高;一级质谱中,离子的质量轴波动减小到之前的一半,响应值提高了10%以上,二级质谱离子的隔离效率提高了1.6倍。     

基于MM1200B质谱系统的MDD模式~(40)Ar/~(39)Ar实验技术及其在阿尔金山中生代冷却中研究中的应用

基于MM1 2 0 0B惰性气体质谱系统 ,建立多重扩散域 (MDD)模式40 Ar 39Ar热年代学实验方法 ,应用该方法的实验结果结合其它年代学数据 ,讨论了阿尔金山中生代的冷却历史。     

Historical and contemporary stable isotope tracer approaches to studying mammalian protein metabolism

Over a century ago, Frederick Soddy provided the first evidence for the existence of isotopes; elements that occupy the same position in the periodic table are essentially chemically identical but differ in mass due to a different number of neutrons within the atomic nucleus. Allied to the discovery of isotopes was the development of some of the first forms of mass spectrometers, driven forward by the Nobel laureates JJ Thomson and FW Aston, enabling the accurate separation, identification, and quantification of the relative abundance of these isotopes. As a result, within a few years, the number of known isotopes both stable and radioactive had greatly increased and there are now over 300 stable or radioisotopes presently known. Unknown at the time, however, was the potential utility of these isotopes within biological disciplines, it was soon discovered that these stable isotopes, particularly those of carbon (¹³C), nitrogen (¹⁵N), oxygen (¹⁸O), and hydrogen (²H) could be chemically introduced into organic compounds, such as fatty acids, amino acids, and sugars, and used to “trace” the metabolic fate of these compounds within biological systems. From this important breakthrough, the age of the isotope tracer was born. Over the following 80 yrs, stable isotopes would become a vital tool in not only the biological sciences, but also areas as diverse as forensics, geology, and art. This progress has been almost exclusively driven through the development of new and innovative mass spectrometry equipment from IRMS to GC‐MS to LC‐MS, which has allowed for the accurate quantitation of isotopic abundance within samples of complex matrices. This historical review details the development of stable isotope tracers as metabolic tools, with particular reference to their use in monitoring protein metabolism, highlighting the unique array of tools that are now available for the investigation of protein metabolism in vivo at a whole body down to a single protein level. Importantly, it will detail how this development has been closely aligned to the technological development within the area of mass spectrometry. Without the dedicated development provided by these mass spectrometrists over the past century, the use of stable isotope tracers within the field of protein metabolism would not be as widely applied as it is today, this relationship will no doubt continue to flourish in the future and stable isotope tracers will maintain their importance as a tool within the biological sciences for many years to come. © 2016 The Authors. Mass Spectrometry Reviews Published by Wiley Periodicals, Inc. Mass Spec Rev     

The COMBAS fragment separator

The basic ion-optical characteristics of the COMBAS fragment separator are analyzed. The momentum distributions of radioactive ⁶He, ⁸He, and ⁹Li nuclei obtained in the reaction ¹¹B (33 A MeV, where A is the mass number of a particle) + ⁹Be (332.6 mg/cm²) have been investigated in forward-angle measurements on the COMBAS fragment separator. The momentum and angular (horizontal) acceptances of the COMBAS separator have been measured using the ⁶He, ⁸He, and ⁹Li beams. It has been ascertained that the images of the ⁶He, ⁸He, and ⁹Li nuclear beams in final achromatic focus of the separator F _a approximately twofold exceed the size of the beam on a producing target (input focus F ₀), at which the primary beam has a diameter of 6 mm. The intensities of ⁶He, ⁸He, and ⁹Li beams obtained at a 5-μA intensity of the primary ¹¹B beam are 6.9 × 10⁵, 2 × 10⁴, and 4.7 × 10⁵ particles/s, respectively. These values are sufficient for use in spectroscopic measurements. It is proposed that time-of-flight analysis of nuclear reaction products at the exit from the COMBAS separator will be used not only to measure the energy of transported particles over the whole operating range of the momentum acceptance, but also to identify them by mass A and charge Z without loss of these particles. The problem of reducing the count rates of detectors and further improvement of their energy resolution for detected particles can be solved by placing a high-resolution magnetic spectrometer past the second target accepting the secondary radioactive nuclear beams.     

A Laser Mass Spectrometer with the Secondary CuBe Emitter for Amplification of Pulses from Multiply Charged Ions of Laser Plasma

A laser mass spectrometer with the secondary CuBe emitter was used to amply weak pulses of multiply charged ions of laser plasma. The use of the secondary emitter helped increase the spectrometer sensitivity by one to two orders of magnitude and detect the pulses of multiply charged ions (Al⁴⁺, Al⁵⁺, and Al⁶⁺) of laser plasma. The pump power density was 50 GW/cm².     

A time-of-flight mass spectrometer for monitoring the inhalational anesthesia concentration in the real-time mode

The use of a medical mass spectrometer for measuring the concentration of the gas mixture components in the breathing circuit of an inhalational anesthesia machine in the real-time mode is described. The resolution of the mass spectrometer is M/ΔM = 200, and the detection threshold in terms of the partial pressure of the analyzed gases is 2 × 10^?12 mbar. The mass spectrometer is capable of measuring the volumetric content of CO₂, O₂, and inhalational anesthetic sevoflurane. The respiratory coefficient (CO₂/O₂) was measured during anesthesia to estimate the patient’s stress reaction to a surgical injury.     

HPLC-ICP-MS联机技术与同位素稀释质谱法应用于鱼中甲基汞的分析

The precise determination of methylmercury (MeHg) in fish tissues has been performed by species specific isotope dilution mass spectrometricanalysis (IDMS) using an inductively coupled plasma mass spectrometer as detector after liquid chromatography (LC-ICP-MS). A labelled MeHg standard (ERM AE670, a Hg 202 enriched methylmercury isotopic reference material) commercial isotope provided by IRMM (Geel, Belgium) was used for these determinations. The experiment procedure included spiking, extraction, and a simultaneous separation and detection procedure. The method gave yield to good precision (<2%). The accuracy of the method has been validated on the certified reference materials BCR 464 (5.50±0.17 mg/kg MeHg) for the tunafish. The result obtained was in good agreement with the certified reference value. And this method was used to do the international comparison CCQM P39.1.     

气体组分和气体同位素分析

本文报道了采用质谱法测量气体组分和Ｎ、Ａｒ同位素的一些结果，供研究与应用参考。     

橙汁中总糖和果肉的δ13C测定及应用

稳定碳同位素分析是食品质量鉴别和产地溯源的有效手段。本工作结合分离技术,建立了元素分析-稳定同位素比值质谱（EA-IRMS）测定橙汁中总糖和果肉δ¹³C的方法,并研究了天然橙汁与模拟造假橙汁中总糖和果肉的碳同位素特征差异。实验结果表明,本方法不会导致同位素分馏,且标准偏差仅为0.1‰;初步研究证明,橙汁总糖与果肉的δ¹³C相近,而与甘蔗糖的δ¹³C差异明显,因此,以橙汁果肉作为内标物质鉴别橙汁中的C4植物糖是可行的。     

四极质谱中的离子—分子缔合反应：Ⅰ.芳香酸及其衍生物的四极质谱

用Finnigan MAT-4510型仪器,在进样方式为DEP的条件下,对六十种不同类型的芳香酸及其衍生物进行了质谱测定。发现在某些结构条件下,会生成[M ArCO]~ 和[M Ar]~ 等加合离子。详细探讨了发生这种离子-分子缔合反应的条件、规律和机理,阐述了离子-分了缔合反应的意义。     

A sectioned spectrometer of fast neutrons

Development of a capture gated spectrometer on the basis of a liquid organic scintillator doped with enriched ⁶Li is discussed. Particular interest is evoked by the good pulse height resolution of the spectrometer for 14-MeV neutrons, which is expected to be very high, ～10–15%. This resolution is attained by compensating for the nonlinearity of the light yield in the scintillator owing to the use of separate optically isolated sections, which independently detect scintillations from each recoil proton. The detector is sensitive to fluence rates ranging from 10^?4 to 10² cm^?2 s^?1 above a threshold of 500 keV under conditions of uncorrelated γ-ray background at a level of up to 10² s^?1 (E > 100 keV). A pilot model of the detector based on a scintillator without a lithium dopant has been produced and tested. The detector efficiency is governed by the scintillator volume (～1.2 l); for 3-MeV neutrons, its value is 0.2–0.5%. The response of the pilot detector to neutrons from a Pu-α-Be source with energies of up to 10 MeV has been measured. Initial testing indicates a low threshold at an ～600-keV energy of a recoil proton. A good spectral response is obtained using the criterion that three optical sections of the detector operate at a time. This spectrometer can find application in low-background experiments in basic physics research, as well as in space research and nuclear medicine for measuring the parameters of the neutron flux.     

Diamond-like carbon coatings with nanocomposite structure formed by reactive magnetron sputtering of chrome in an Ar + C2H2 + N2 gas mixture and their tribological behavior

Results of a complex study of the structure, the phase and chemical compositions, the microhardness, as well as the nanomechanical and tribological properties of a-C: H: Cr: N hydrogenated amorphous carbon coatings are presented; these coatings were formed by the reactive magnetron sputtering of chromium at various concentrations of nitrogen and acetylene in the active Ar + C₂H₂ + N₂ gas mixture. Raman spectroscopy has shown that carbon in these coatings is represented by a disordered mixture of regions with tetrahedral (sp ³) and hexagonal (sp ²) coordination of carbon atoms. The alloying metal in the coating formed nanosized inclusions of metal chrome, as well as of its carbide and nitride phases. It has been shown that the additional alloying of a-C: H: Cr coatings with nitrogen, which leads to the formation of chromium nitride, makes it possible to improve their mechanical and tribological characteristics.     

A device for the preliminary separation of ions for mass spectrometry analysis

A device for the preliminary separation of ions based on an ion mobility increment spectrometer with cylindrical geometry of its electrodes is described. The device is operated in tandem with an atmospheric-pressure ionization mass spectrometer. The use of the spectrometer in the preliminary separation of ions of the target substance from ions of the chemical noise is illustrated by investigating the vapor above a water solution of acrylamide (CH₂=CH-CO-NH₂) with a concentration of 1.4 × 10⁻⁵ mol/L. The resolution of the device is rather low, R ∼ 10–20; nevertheless, thanks to its simplicity and availability, the device may find application to routine chemical analysis and in portable instruments.     

A Plane Parallel Chamber Used as a Stopped Muon Detector for the Active Target of the FAMILON Project

The performance characteristics of a plane parallel chamber were investigated on beams of slow muons and positrons, as well as on an electron beam from a ¹⁰⁶Ru β source. The chamber was filled with CO₂ or a gas mixture of Ar (30%) + CO₂(70%) at atmospheric pressure. The amplitude spectra of charged particles and the efficiency of their detection were measured. The muon and positron momenta were ∼27 MeV/c. It was shown that the muon detection efficiency of the plane parallel chamber with a 1-mm gas gap and CO₂ (100%) used as a working gas was as high as 99%, while that of the chamber with a 0.4-mm gas gap and a working gas mixture of Ar(30%) + CO₂(70%) was 88%. This result, along with the detector's high response speed, allows the plane parallel chamber to be used as an active target being developed for a future experiment (FAMILON) on searching for neutrinoless muon decay with the release of a scalar Goldstone's boson (μ → eα). __________ Translated from Pribory i Tekhnika Eksperimenta, No. 5, 2005, pp. 29–35. Original Russian Text Copyright ? 2005 by Vorobyev, Gordeev, Zhdanov, Elkin, Ivochkin, Komarov, Kosianenko, Scheglov, Scherbakov.     

A spectrometer for seeking exotic states of pionic atoms of xenon

The parameters of a spectrometer for searching for deeply bound pionic states of xenon are presented. The main component of the spectrometer is a multilayer semiconductor telescope based on high-purity germanium detectors. A technique for calibrating the spectrometer and measuring its energy resolution using reactions p(d, ³He)π⁰ and ¹⁴N(d, ³He)¹³C is described. The energy resolution of the setup is shown to be 0.85 MeV for ³He ions with an energy of ～360 MeV.