Many numerical simulation models for analytical and industrial ICP sources have been developed; hence, experimental verification is essential. Compared with plasma temperature, the flow velocity profile is a direct and reliable criterion for model verification. In this paper, an experimental study on the dynamic properties of a home-made analytical ICP source and its tail flame is conducted using a high-speed colour camera and a high-speed fibre-optic spectrometer, and the spatially resolved pulsation frequency and flow velocity are presented. The pulsation frequencies of the plasma area and emission intensity were experimentally determined, respectively. The spatially resolved pulsation frequency indicates that pulsation of the normal analytical zone (NAZ) is very stable and synchronous, and the tail flame fluctuates due to ambient air entrainment. The flow velocity in the coolant gas was characterised by tracking the trajectories of injected alumina powder particles. After correcting for the velocity difference between the powder particle with high inertia and the surrounding flow, a plausible range of axial (Vz) and radial (Vr) velocity at the outer edge of the coolant gas is proposed. The flow velocity on the axis downstream of the NAZ was experimentally determined by tracking and interpolating the velocity of discrete erbium ion clouds originating from individual erbia suspension particles. By comparing the simulated profile of axial velocity with the experimental profile, the power coupling efficiency of the present ICP facility is estimated to be around 80%. A linear expression is presented to describe the variation of Vz with the axial position (z) in the range of 0 <= z <= 50 mm. Because erbium ion clouds were not distinguishable from the very bright emission background within the NAZ, a novel method is proposed to determine the flow velocity in the NAZ by combining the dependence of the audio frequency of plasma pulsation on the flow velocity profile, the simulated profile of axial velocity, and the experimental value of pulsation frequency. The determined value of axial velocity at the torch outlet axis operating at an r.f. power of 1200 W is in good agreement with the fitted value. This work presents complete experimental data on flow velocity in a single ICP facility and experimentally verifies the previously developed 2D numerical model.

Uncovering the nature of dark matter microscopic particles is one of the most important disciplinary goals of physics and astronomy in the 21st century, and how to reduce background signals and environmental interference in dark matter experiments is one of the key factors to improve the sensitivity of the detector and to take the lead in obtaining significant detection results. High-purity nitrogen, as a crucial gas for detector purging, scintillator purification and pipe cleaning, among other things, contains the radioactive gases 85Kr and 81Kr in natural Kr, which emit beta-rays that can interfere with the detection of dark matter signals. Therefore, it is necessary to measure the concentration of ultra-trace level Kr in high-purity nitrogen, and screen high-purity nitrogen complying with the standard for use in dark matter experiments. This study develops a novel analytical method to determine ultra-trace level Kr in high-purity nitrogen using a static noble gas mass spectrometer coupled with a newly designed sample processing system. A large amount of reactive gases from the original sample are removed by the large-volume high-temperature purification device, and then we explore a simple and iterative trapping method for Ar-Kr separation. This method improves the noble gas separation factor with the promise of ensuring recovery. The separated Kr is fed into a static vacuum mass spectrometer. The detection limit of this method for natural Kr is as low as 10-14 L L-1 with an uncertainty of about 8%. This paper has developed newly an sample processing system combined with a static vacuum mass spectrometer to study how to measure 10-12 level krypton in high-purity nitrogen.

The principles of different ballistic deficit correct (BDC) methods were discussed and verified at length in time domain. Confirmations were theoretically done for an existed BDC algorithm based on point by point calculation. Three new BDC formulas were deduced with the same principle. Moving Window Deconvolution (MWD) for BDC was deduced theoretically in time domain for the first time, which proves that it is a unified method for all above confirmed BDC formulas. The correct precision of these methods realized in digital signal processing was discussed carefully. And corresponding simulations were done to verify the discussed result which showed that smaller λ and higher sample frequency f s can make good BDC precision.

A high accuracy method for Xenon isotope abundance measurements was developed on a Helix MC Plus static gas mass spectrometer，in order to solve the problem that the mass difference of the nine stable isotopes of Xe is large (about 9.6%) and the mass spectrometry detector is difficult to accept, for get the abundance of all the stable isotopes of Xe quickly and accurately. The gas sample containing Xenon was purified and separated before introduced into the mass spectrometer analyzing chamber firstly, which helps reducing the influence on Xenon isotopic measurement brought by other noble gases and active components. Then, a measurement method combining peak hopping and multi reception was used to achieve high precision measurement of all stable isotopes of Xe at extremely small sample amount based on the Helix MC Plus static gas mass spectrometer. The measured data were corrected by referring to the Xenon isotopic reference gas finally. Results show that, under the condition of small sample amount (approximately 1.12×10-12 mol), the relative standard deviation (RSD) of the measured 129Xe/132Xe, 130Xe/132Xe, 131Xe/132Xe, 134Xe/132Xe, 136Xe/132Xe were within 0.24% by Faraday, and 124Xe/132Xe, 126Xe/132Xe were within 0.22% and 0.39% by counting method separately. This method achieves abundance ratio analysis of trace Xe stable isotopes with good stability and high accuracy.

Xenon（Xe） isotopes from nuclear test and accidents are important monitoring components of the comprehensive nuclear test ban treaty（CTBT）.An approach for the reproducible and accurate compositional analysis of Xe isotope ratios by multiple collector inductively coupled plasma mass spectrometry（MC-ICP-MS） was described in this paper.A Xe enrichment and purification platform was established to separate Xe from the collected atmosphere gas,enriching the Xe concentration and utilizing high purity argon as aerosol carrier,thus resulting in eliminating the negative influences of organic compound and particles on mass spectrometry.A relible Xe injection system was built to control the gas flow rate between the sample and the MC-ICP-MS in order to improve the stability and reproducibility of the ion-signals.Furthermore,several measures,including adsorbing Xe from the sample gas for mass spectrometry and baking the Xe introduction device for 2 hours with vaccum pumping,were taken to reduce the Xe blank.As a result,the blank signal of 129 Xe falled from 3.0 × 10 -2 V to 2.7 × 10 -3 V.Analyses were performed on a Neptune XT MC-ICP-MS,and standard sample bracketing（SSB） was involved in correcting the mass fractionation.The approach was successfully validated by the measurement of standard reference materials in 24 hours,showing that the relative uncertainties for all Xe isotope ratios were less than 0.09%（n = 7）,while the results agreed with the certificated values within uncertainty range.Especially,the relative uncertainties for 130 Xe/ 131 Xe and 132 Xe/ 131 Xe ratios were 0.007 1% and 0.006 9%,respectively.Two kinds of atmosphere gas collected at different times were analyzed and distinguished successfully by the proposed approcach.The results demonstrated that the developed technique was a precise and accurate method for Xe isotope dectection,Xe monitoring event identification and event sourcing.

The commercial Hexin Single particle aerosol mass spectrometer (SPAMS) has been widely used for environmental aerosol monitoring and source apportionment. However, particle size measurement is easily affected by environment pressure fluctuation and sampling orifice clogging. The capability for quantitative analysis is poor, and few isotope measurement has been reported. This paper aims to evaluate the analytical performance of SPAMS and extend its application. First, the flight time of standard particles having different densities and sizes was measured under various conditions (aerodynamic lens upstream pressure and carrier gas). We proposed a universal method for particle size calibration, measurement and correction, taking into account the effects of lens geometry (acceleration nozzle diameter), particle parameters (density, diameter, and shape factor), and operating conditions (lens upstream pressure and carrier gas). Then, isotope measurement was performed when introducing a solution droplet containing a single element. Metal oxide and metal cluster ions were observed in the mass spectrum, indicating incomplete ionization of the sample droplet. The mass discrimination effect was carefully evaluated to correct the measured isotope ratio. Results show that the achievable accuracy of the corrected isotope ratio for elements investigated was 5%. The instrumental performance was relatively poor for elements having great ionization potential or bond energy. Finally, Ag/Eu2O3 suspension and yellow cake/ ethanol suspension were analyzed for size, elemental and isotopic analysis. We confirmed that the mass discrimination effect during suspension introduction could be corrected using the mass discrimination correction factor obtained during solution introduction. The Ag, Eu and U in these suspension particles were all found to be at natural abundance. The uranium in the yellow cake was identified as sodium duranyate (Na2U2O7) with volumetric equivalent diameter of approximately 65 nm. The work presented here is beneficial for instrument improvement and wide application.

为制备满足放射性测量需求的Kr气体源,需对含Kr气体中的高浓度CH4进行初步分离,本文开展了催化燃烧法分离CH4和Kr的实验研究.研究结果表明,CH4的催化燃烧转化率随CH4浓度和催化温度的升高而增加,H2对CH4催化燃烧的抑制作用随着H2浓度的升高而变大,CO对CH4催化燃烧的抑制作用随着CO浓度的升高而变小,模拟气中的CH4在适宜的催化燃烧条件下可有效去除.

In conventional isotopic dilution method , when target isotope in a sample is influenced by the tracing material , it should be measured includes not only the isotope ratios of the mixture of dilution and sample, but also that of the original sample. In case that sample is insufficient, or measuring time is limited, the isotope dilute method meets its embarrassment. In this study, an efficient quantitative isotopic dilution method was provided, in which the measurement of the isotope ratios in the sample was unnecessary. This method had particularly advantage on reducing sample consumption, simplifying the measurement procedure and decreasing the influence of memory effect, which greatly improved the efficiency of the measurement. The six measurements showed that xenon standard gas was used to verify its applicability , which provided a bias of less than 1% to the nominal value and a relative standard deviation (RSD) of 0. 4%. The measurement result was completely consistent with the value of conventional isotope dilution. In tracing experiment with Xe-128 despite of the interference of natural xenon, (12) Xe of tracer was precisely determined. The diffusion curve which was drawn by Xe-128 also accorded with the rule of gas diffusion in the closed space. This method was suitable only for elements that with three or more isotopes.

对甲烷(CH4)与氪(Kr)共吸附条件下的脱附行为开展了实验研究.研究了脱附温度、升温速率和吹扫流量对CH4和Kr脱附行为的影响.实验结果表明:CH4和Kr具有相似的脱附行为,在不同脱附温度、升温速率和吹扫流量下,CH4和Kr脱附曲线的峰形和峰位基本相同;CH4和Kr脱附曲线的出峰时间随脱附温度、升温速率和瞬时吹扫流量的增加而缩短,而CH4和Kr的脱附曲线随累积吹扫流量的变化趋势在不同瞬时吹扫流量下基本相同.

The preparation of subnanoporous covalent-organic-framework (COF) membranes with high performance for ion/molecule sieving still remains a great challenge. In addition to the difficulties in fabricating large-area COF membranes, the main reason is that the pore size of 2D COFs is much larger than that of most gas molecules and/or ions. It is urgently required to further narrow their pore sizes to meet different separation demands. Herein, we report a simple and scalable way to grow large-area, pliable, free-standing COF membranes via a one-step route at organic–organic interface. The pore sizes of the membranes can be adjusted from >1 nm to sub-nm scale by changing the stacking mode of COF layers from AA to AB stacking. The obtained AB stacking COF membrane composed of highly-ordered nanoflakes is demonstrated to have narrow aperture (∼0.6 nm), uniform pore distribution and shows good potential in organic solvent nanofiltration, water treatment and gas separation.

针对核电站检修用PVC塑料布的减容处理,建立了大功率微波热解减容技术及设备,通过对微波减容实验过程中的尾气成分分析,详细研究了PVC塑料布的微波热解技术条件及机理,并与PVC常规热解行为及机理进行了比较.结果 表明,在微波照射条件下,PVC分解过程分为3个阶段..80～140℃为脱HCl阶段;140～250℃为裂解碳化阶段;250℃以上为灰化阶段.与常规热解相比,微波照射可使PVC塑料布在较低温度下迅速脱氯,并可通过调节微波加热功率,控制升温程序,从而显著降低PVC塑料布热解过程中二嗯英的产生.

激光共振电离质谱是激光共振电离技术和质谱技术相结合的一种新型质谱分析技术,具有高元素选择性和高灵敏度的特点,能有效克服商业质谱仪存在的同量异位素干扰难题.为满足复杂基体干扰下超痕量核素分析测量的需求,实验室研制了一台基于磁-电双聚焦质量分析器的激光共振电离质谱仪.该装置的质量分析器采用正向Nier-Johnson型双聚焦结构,由柱形静电分析器和扇形磁质量分析器组成.本文介绍了仪器质量分析器的结构和理论参数,并对其进行理论仿真与实验测试.结果表明,该仪器实现了方向和能量双方向聚焦,具有较小的高阶像差,仪器的水平方向放大率为0.78,质量色散达到500 mm,当源狭缝宽度0.25 mm、探测器入口狭缝宽度0.65 mm时,质量分辨率(10％ 峰谷)达到580左右,接近质量分辨率的理论极限605.最后,介绍了本实验室利用该仪器开展的分析测量工作,展示了该装置在强同量异位素干扰下超痕量核素测量方面的部分应用情况.

高精密度地测量铀材料中的铀同位素组成信息,特别是低丰度铀同位素234U和286U,是核取证研究的重要内容.本研究采用多接收电感耦合等离子体质谱(MC-ICP-MS)测量铀同位素比值,将两种黄饼样品的酸消解液制备成238U浓度约21 000 ng/g和180 ng/g的待测样品,采用外标标准化法和标准样品交叉法校正质量分馏效应,MC-ICP MS对238U浓度约180 ng/g的样品中235U/238U测量的相对实验标准偏差可低于0.014％.为降低超档离子流信号对低丰度铀同位素分析的影响,建立了法拉第杯接地方法,使轰击到法拉第杯上的238 U+产生的电流在到达前置放大器之前被引入大地,该方法对238U浓度约21 000 ng/g的样品中234U/235U测量的相对实验标准偏差可低于0.020％,对浓缩铀GBW04234和GBW04238中236U/235U测量的相对实验标准偏差小于0.11％,测量结果与参考值在不确定度范围内一致.该方法的精密度较高、结果准确,可识别铀同位素组成存在一定差异的核材料,为核取证和核保障监督提供技术支持.

Laser-resonance-ionization time-of-flight mass spectrometer (LRI-TOF-MS) has been widely used in the analysis of trace isotopes because of its advantages such as high isotope selectivity, high sensitivity, and capability to receive all isotopes in a single measurement. A LRI-TOF-MS was built in our laboratory to search for efficient laser resonance ionization scheme of some elements and analyse their isotopic composition. To improve the resolution and suppress the peak tail, the orthogonal-acceleration technology was used in LRI-TOF-MS for the first time, and the design method of electrical parameters of TOF mass analyser with dual-stage reflectrons was derived. The developed ion guide device consisted of several different electrostatic lenses and was manufactured through theoretical analysis, SIMION simulation and experimental evaluation. The results show that the LRI source and the TOF mass analyser matched well in performance. (C) 2018 Published by Elsevier B.V.

Ion energy distribution is one of the main factors that influence the resolution of time-of-flight mass spectrometer(TOF MS).One-stage or dual-stage energy focusing method was used to improve the resolution of TOF MS by reducing the ion flight time range.This method was very efficient for the ions with low energy range and large energy range ions,the resolution reduced rapidly.T hus,a broad energy range focusing reflectron method was proposed by Vlasak P.R.for TOF MS,which was applied the various voltages for the electrodes with certain distances.In this paper,a modified method was put forward by optimizing the distance and voltage of the electrodes for the reflectron simultaneously,and the validity of the method was proved by SIMION simu-lation.The errors caused by machining precision and assembly accuracy could be com-pensated by adjusting the voltages of the electrodes.To prevent the penetration of the fields,the electrodes should be equipped with grids.But the transmission of the ions will decrease very fast with the number of the grids increasing.By this method,the intensity of the first stage electric field was much larger than the others.Apart from the first two stage electric field,the intensity of the electric field was only a little larger than the field before.So all the grids can be removed but only the first two grids,which can prevent the first stage electric field penetrate to other fields.The penetration of oth-er fields can be compensated by adjusting the electrodes voltages a bit.The simulation results showed that the method is simple and effective,and has strong practicability.

The two-color three-photon photoionization technique was used to obtain information on high-lying excited even-parity levels of atomic neodymium in the 32,100-35,300 cm(-1) energy region. 417 even-parity levels, most of which were reported for the first time, were revealed. Out of these, 172 levels were assigned unique J values based on the J-momentum selection rule. The absolute accuracy of these levels was estimated to be better than +/- 0.2 cm(-1). (C) 2018 Published by Elsevier B.V.

A preliminary method based on the laser resonance ionization mass spectrometer (LRIMS) developed in the laboratory was established to determine tin isotope ratios. By measuring the auto. ionization spectrum of tin atoms, a three. color. three. photon resonance ionization scheme was confirmed, and the laser wavelengths of each excitation/ionization step were. lambda(1) = 286. 4 nm, lambda(2) = 811. 6 nm and lambda(3) = 823. 7 nm. More effective electrothermal atomization of tin was implemented by mixing the samples and grapheme oxide solution, and the total detection efficiency of 1 mu g of tin sample was above 3x10(-5), which was about 4.5 times as high as the method of directly dropping samples. A tin. antimony. tellurium mixture at a ratio of 1. 1. 1 (m/m) was prepared as a simulant sample, and the major tin isotope ratios in the sample were determined. Results showed that the isobaric interference from antimony and tellurium was effectively avoided, and the relative standard deviations for Sn-116/(120) Sn, Sn-117/(120) Sn, Sn-118/(120) Sn, Sn-119/(120) Sn were all better than 1%. This work indicated that LRIMS could effectively avoid the isobaric interference in the measurement of tin isotope ratios, and could be applied to measure the fission product (121)mSn and Sn-126 in the reactor spent fuel.

The isotopic fingerprints of plutonium are extremely important for nuclear safeguards and nuclear forensics. An analytical method was developed for direct determination of Pu-239/Pu-240 ratio in plutonium containing particles by laser ablation multiple collector inductively coupled plasma mass spectrometry (LAMC-ICP-MS). The risk of ablated particles leakage was reduced by leak detection, exhaust hood, and swiping the laser cell. Scanning mobility particle sizer (SMPS) was used to measure the effect of ablation parameters on the size distribution of ablated particles. The results showed that the majority of ablation material presented as particles from 40-500 nm and the sweep time after laser ablation should be longer than 15 min. The particle size was evaluated to guide LA-MC-ICP-MS system. By using external normalization method for correction of the mass fractionation correction factor and ion counter efficiencies measured by nebulizer-coupled MC-ICP-MS, a LA-MC-ICP-MS method was established for analysis of Pu-239/Pu-240 ratio in plutonium particles. Spot size, ablation rate and laser dwell time were set at 30 mu m, 5 Hz and 5 s, respectively. Laser energy density was controlled to ensure that the intensities of (PU)-P-239 for plutonium-containing particles were about 2 x10(4) cps and 2 x10(5) cps, respectively. The analytical results showed that the relative uncertainties for Pu-239/Pu-240 was less than 1. 4% (n = 6), and the measured value deviated by less than 4. 7% from the reference value. The time for adjusting system and determining Pu-239/Pu-240 ratio in single plutonium particle was 9 h and 0. 5 h, respectively. The results demonstrated that this technique was rapid, precise and accurate, and could be used for determination of Pu-239/Pu-240 in plutonium-containing particles.

Laser resonance ionization spectroscopy (LRIS) is one of the element-selective spectroscopy methods, which aims to study the energy level parameters of the atom by measuring the ion signal. The atom is selectively excited and ionized by one or more lasers in LRIS. A set of totally domestic LRIS apparatus was built, which was used for measuring the parameters of the atomic high lying states. The overall structure, main technique and application of the LRIS apparatus were described in detail. The LRIS system was consisted of high precision tunable dye lasers, high efficiency laser ionization system and high resolution time of flight mass analyzer (ToF-MA). There were three sets of multimode dye laser and one set of single longitudinal mode dye laser, which were pumped by 532 nm Nd : YAG laser. The repetition frequency of the dye laser was 10 kHz. The laser ionization system contained atomization source, atom and laser interreaction region and ion lens. The atom sprayed from the atomic source was selectively excited and ionized by lasers, and then was reshaped as ion beam with small divergence angle and narrow beam width by ion lens. The reflecting structural design, pulsing vertical repulsion technique and deflecting plate adjusting method were adopted in the ToF-1VIA. Based on the laser resonance ionization spectroscopy technique, the auto-ionization spectrum of uranium atom was measured with the aid of this apparatus. An efficient three-color-three-photon resonance ionization scheme of uranium atom was obtained. The center wavelengths of the lasers were 591. 7, 565. 0 and 632. 4 nm, respectively. The isotopic shift and the hyperfine structure also can be analyzed by this apparatus. In addition, as result of the mass analyzer employment, the proposed apparatus can be used to analyze the sample component, trace element concentration, and isotopic abundance.

The isotopic abundance of lead as a signature or fingerprint in uranium has played an important role in nuclear forensics analysis. In this work, a novel analytical approach is presented to determine the isotopic abundance of lead in uranium particles by laser ablation multiple collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). External standardization method is involved in correcting the mass fractionation in the process of analysis. The approach has been successfully validated by the measurement of CRM124-4 standard reference material. Spot size and ablation rate are set at 30 mu m and 20 Hz, respectively. Laser energy density is under control to ensure that the Pb-208 for NIST SRM612 and uranium particles are less than 1.5x10(5) cps and 3x10(4) cps, respectively. The results show that the relative uncertainty of Pb-206/Pb-208, Pb-206/Pb-207 and Pb-207/Pb-208 ratios in CRM124-4 are less than 0. 48%, 0. 68% and 0. 40%, respectively. Two kinds of uranium particles originated from different places have been analyzed by the proposed approach. The results demonstrate that the distinct lead isotope signatures can offer a number of evidence to determine whether the uranium particles have come directly from a mining operation or an ore-body, or whether it is anthropogenic.