In order to calibrate the instrument in real-time for on-line quantitative analysis of airborne particles with ICP-MS,an isotopic aerosol particle addition calibration method was developed in our laboratory.In this paper,the method was introduced in detail and validated using artificially generated particle containing uranium.First,aerosol generation efficiency and solution uptake rate of nebulization sample introduction system were determined accurately through experiments.Natural uranium standard solution was prepared for generation of micron-size and monodisperse particle by a commercial Vibrating Orifice Aerosol Generator(VOAG).Isotope was selected to overcome the mass discrimination effect.233U standard solution was prepared for nebulization of 233U containing particles.The discrete 238U containing particle and continuous 233U containing droplets were mixed together,desolvated in a membrane dryer,and introduced into ICP-MS for on-line analysis.Peak-jump mode was used to monitor 233U ion intensity and 238U ion count.Instrument sensitivity for 233U was calibrated in real-time.After mass discrimination correction,atom number of 238U in individual particle was determined.Results show precision of measured 238U atom number in individual particle is 5.6%.The discrepancy with the calculated value based on VOAG operation parameters is 19% and the possible reasons were discussed preliminarily.

A technique for direction introduction and on-line quantitative analysis of aerosol particle by ICP-MS has been developed. Fast determination of Pu-239 concentration in aerosols based on Pu-242 aerosol particle addition calibration method and sampled by steel cylinders samplers from nuclear environment has been conducted. Results show that detection limit for Pu-239 concentration is 1.4 x 10(-3) Bq/m(3). The concentrations in these aerosol samples are between 3.1 x 10(-3) and 1.2 x 10(-2) Bq/m(3), all of which are at least one order of magnitude lower than the statutory tolerance.

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-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ICP-MS联用.本文介绍了该狭缝虚拟撞击器的研制情况:首先由ICP-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11 L/min,强流与弱流的流量比为10,喷射狭缝宽度为1 mm,长宽比为10;然后用计算流体动力学软件Fluent 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1.4～1.6 mm,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.

When more than two elements on the filament of a thermal ionization mass spectrometer(TIMS) are vaporized,the element ratios in the vapor depend on the filament temperature.The ion current ratios of different mass numbers vary with the temperature,which is dominated by the filament current.With the presence of isobaric interference,the method of isotopic analysis by TIMS is established in the present paper and applied to determine the natural lutetium abundance in the solutions,in which ytterbium and lutetium are mixed by ratio of 1 000∶1.The measured isotope ratio of lutetium is in good agreement with the standard value.Likewise,the concentrations of 173Lu and 174Lu in the real samples produced through bombardment of ytterbium target by proton beam are determined by ID-TIMS.The relative uncertainties of concentrations are 0.45% and 1.1%,respectively.

The method of lutetium isotopic ratio determined by thermal ionization mass spectrometry (TIMS) with a mass of interference isobars Yb was developed. In this method, isotopic ratio of Lu R176/175 was analysed by linear least square method. The uncertainty of values mainly came from the type A uncertainty of the regression.

This paper describes the investigation of even-parity autoionization states of cerium atoms by three-step three-color resonance ionization spectroscopy (RIS). Twenty-seven odd-parity highly excited levels, whose transition probability is high, were used in this research. One hundred and forty-one autoionization states were found by these channels with the third-step laser scanning in the wavelength range of 634-670 nm. The ionization probabilities of different channels, which had higher cross sections, were compared. On the basis of this, eight optimal photoionization schemes of cerium atom have been given.

Plutonium in soil was separated using tri-octylamine extraction chromatography and measured by inductively coupled plasma mass spectrometry ( ICP-MS). The background of Pu-239 for the procedure was 0.036 +/- 0.025 pg, and the detection limit was 0.25 pg accordingly. The concentrations of Pu-239 are presented to be 0.2 pg/g and 1 pg/g in Xian and Gansu, respectively. Plutonium isotopic ratio, Pu-240 to Pu-239, was also obtained for 0. 18 at Van and 0. 15 at Gansu, respectively. These results show that the plutonium source in Van is derived from global fallout, beside it other plutonium source existed in Gansu.

Laser resonance ionization spectroscopy (RIS) is an excellent technique for investigating the complicated atomic structure of heavy elements especially in their higher-energy region. In order to obtain the optimal photoionization scheme of cerium atom, odd-parity high-lying states were studied using this technique. The 83 odd-parity high-lying levers have been firstly observed by two-step resonance laser excitation followed by non-resonance photoionization in the 32,042-34,575 cm-1 energy region. These high-lying states have been measured. The possible angular momentum quantum numbers J are assigned for these levels.

A double-focused ICP-MS coupled with a membrane desolvating sample introduction system is used for the determination of ultra-trace plutonium in atmospheric aerosols. 242Pu is used as spike for the isotope dilution analysis. The detection limit of 239Pu obtained is 0.4 fg/mL. The matrix effect was minimized by matrix separation using extraction chromatography. The limit of determination for plutonium in atmospheric aerosols obtained is 5.7×10 -8 Bq/m 3.

The dependences of laser-induced isotopic discrimination effect on some of laser parameters were studied by the experimental and theoretical methods. This effect mainly stems from the discrepancy of the second-step transition probability between different isotopes. The method by which this effect is lessened or eliminated is given. The isotopic ratios of nature lutetium sample are determined by this method. The experimental results present that the degree of the laser induced isotopic discrimination of lutetium isotope can be lessened by this method.

激光共振电离光谱是一种十分适合于高能量区重元素复杂原子结构研究的技术.为寻找铈原子最佳的共振电离通道,利用这一技术对铈原子奇宇称高激发态进行了研究.在32 042～34 575 cm-1范围内,用两步共振激发和非共振电离方法,首次观察到了83条铈原子奇宇称高激发态能级,测量了这些新能级的能量和给出了可能的总角动量J值.