摘要
电感耦合等离子体质谱仪(ICP-MS)以其灵敏度高、检出限低等优点,是痕量元素强有力的分析手段之一。在ICP-MS仪器设计中,如何将待分析物的离子束有效引入后级质量分析器系统是一大难点。为了实现离子束的高效传输,离子束进入偏转透镜后应有较小的角度发散和能量发散,并尽可能平行射出,即在垂直方向的速度尽量为0;同时为了最大程度去除中性粒子和光子,降低背景噪声,应使垂直方向的偏转位移较大。借鉴电子光学中的静电场理论,从离子在静电场中的运动过程出发,对离子在一种偏振悬挂式离轴偏转透镜中的运动过程进行理论推导并建立模型;通过SIMION仿真软件,分别对代表低、中、高质量数的Li、In、U离子束在此偏转透镜系统中的运动进行模拟仿真,考察了电场参数加速电压U_(a)、偏转电压U_(1)、偏转电压U_(2)和机械参数L2对离子束传输的影响,该影响包括离子偏转位移s y、垂直方向速度V′y和离子通过率;结合仿真结果和设计要求给出该离轴偏转透镜的关键电场参数值和机械参数优化设计方案;根据优化设计方案,将三种设计尺寸的偏转透镜系统应用于ICP-MS仪器中,进行了背景噪声和灵敏度的对比测试以验证模拟仿真可靠性。实验结果表明,借助仿真优化后的透镜结构,背景噪声和灵敏度有明显提升,尤其是低质量数提升更为明显,背景噪声降低了约2倍,灵敏度提升了约4倍。虽然模拟仿真与实际结果有一定的误差,而整体的趋势正确,能够为实际偏转透镜系统的结构设计和电气参数优化提供指导。
Inductively coupled plasma mass spectrometer(ICP-MS)is one of the most powerful analytical methods for trace elements due to its high sensitivity and low detection limit.In the design of ICP-MS instruments,effectively introducing the ion beam of the analyte into the post-mass analyzer system is a major challenge.To achieve efficient transmission of ion beams,the ion beam should have a small angle divergence and energy divergence after entering the deflection lens,and be emitted as parallel as possible.That is,the velocity in the vertical direction should be as low as possible.At the same time,to remove neutral particles and photons to the maximum extent and reduce background noise,the vertical deflection displacement should be made larger.This paper draws on the theory of electrostatic fields in electron optics,starting from the motion process of ions in an electrostatic field,and theoretically derives and establishes a model for the motion process of ions in a polarized suspended off-axis deflection lens.Then,using SIMION software,the motion of Li,In,and U ion beams representing low,medium,and high mass numbers in this deflection lens system is simulated and analyzed.The key electric field parameters acceleration voltage U a,deflection voltage U 1,deflection voltage U_(2),and mechanical parameter L_(2)in theoretical analysis are examined for their effects on ion beam transmission,including ion deflection displacement s y,vertical velocity v′y at the exit hole,and ion pass rate.Combined with simulation results and design,the effects are investigated.Based on the simulation results and design requirements,this article presents the key parameter values and size optimization design scheme for the off-axis deflection lens.According to the optimized design scheme provided by software simulation,three sizes of deflection lens systems were applied to ICP-MS instruments for comparative testing of background noise and sensitivity to verify the reliability of the simulation.The experimental results showed that the background noise and sensitivity were significantly improved with the optimized structure,especially for low-mass numbers.The background noise was reduced by about 2 times and the sensitivity was increased by about 4 times.Although there may be some errors between simulation and actual results,the overall trend is correct.It can guide the structural design and electrical parameter optimization of deflection lens systems in practice.
作者
李凯
王雷
王海舟
王立平
方哲
王超刚
潘高阳
LI Kai;WANG Lei;WANG Hai-zhou;WANG Li-ping;FANG Zhe;WANG Chao-gang;PAN Gao-yang(Central Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China;NCS Testing Technology Co.,Ltd.,Beijing 100081,China)
出处
《光谱学与光谱分析》
北大核心
2025年第3期808-815,共8页
Spectroscopy and Spectral Analysis
基金
国家重点研发计划项目(2021YFF0700103)资助。
作者简介
李凯,女,1985年生,钢铁研究总院有限公司及钢研纳克检测技术股份有限公司高级工程师,e-mail:likai@ncschina.com;通讯作者:王海舟,e-mail:wanghaizhou@ncschina.com。
