摘要:
MRTOF-MS是最近几年发展起来的新型质谱仪,较传统的飞行时间质谱仪而言,MRTOF-MS质量分辨本领更高.开发了一种用于MRTOF-MS设计的新方法,该方法由参数设置部分和离子运动计算部分共同组成;分全局搜索和局部细化两个步骤,可用于优化MRTOF-MS的几何构型、计算不同条件下的最佳电压设置组合.基于这种方法,设计了一种机械结构与国际上同类设备不同的MRTOF-MS,该设备可用于高精度原子核质量测量,也可用于快速质量选择,为LPT提供纯净的目标核.通过优化,确定了其几何参数和电压参数,讨论了不同电极上的电压偏差对质量分辨本领的影响,定量地分析了电源的精度要求.优化结果表明:MRTOF-MS的最佳漂移长度约为400 mm;在最佳电压设置下,当40Ar1+的总飞行时间为6.5 ms时,其质量分辨本领可达1.3×105;要求电源精度好于50 ppm,最好达到20 ppm.
Abstract:
Multi-reflection time-of-flight mass spectrometer (MRTOF-MS) has been developed as a new device which has a higher mass resolving power than traditional mass spectrometers in recent years.A new method including two sub-procedures,global search and local refinement,has been developed and applied to design a MRTOF-MS.It consists of two components,parameter configuration and ion motion simulation,and can be used to optimize the geometries of the spectrometer and the potentials applied on the electrodes to achieve the optimum in different conditions.By using this method,a different type of MRTOF mass analyzer has been designed for mass measurements and isobaric separation for Lanzhou Penning Trap (LPT).The geometry of this analyzer and potentials at different electrodes have been optimized,and the relations between resolving power and potentials and the power accuracy requirements have been analyzed and discussed quantitatively.The simulation shows that the optimal length of the drift-tube is about 400 mm;the maximal resolving power of 1.3 × 105 has been achieved with a total time-of-flight of 6.5 ms under the optimal potentials for an ion species of 40Ar1+;and the inaccuracy of the potentials applied to the mirror electrodes must be less than 50 ppm or preferably 20 ppm.
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