Simulation Research Of The Secondary Ion Optical System In Time-of-flight Secondary Ion Mass Spectrometer

As one of the frontier scientific devices for surface composition analysis,time-of-flight secondary ion mass spectrometer has become more and more widelyused whether in analytical chemistry and environmental science, or in the biomedicalfield because of its characteristics that high resolution, sensitivity and analysis speed,wide measuring range, less sample consumption and so on. The characteristic thatlittle sample consumption makes time-of-flight secondary ion mass spectrometer moresuitable for the analysis of geochronology samples.This topic comes from "National Major Scientific Instruments and EquipmentDevelopment Special Project–TOF-SIMS Scientific Device dedicated to isotopicgeochronology", which aims at developing time-of-flight secondary ion massspectrometer applied in geochronology isotope analysis with high accuracy andresolution. Secondary ion optical system, as a key part in time-of-flight secondary ionmass spectrometer, is mainly used for the extraction, adjustment, focus, separationand detection of the secondary ions. The variation of the parameters in secondary ionoptical system will affect the movement of the secondary ions and then influence theperformance of the instrument, thus the simulation research of the secondary ionoptical system can provide guidance and reference for design and parameter selection.First, combined with the principle and the structure of time-of-flight secondary ionmass spectrometer, the initial movement of the secondary ion and ion optics theory,the structure of the secondary ion optical system and the design scheme of eachcomponent were proposed, and the design schemes were analyzed. Then, thesimulation model of each component in the secondary ion optical system wasestablished in SIMION software, the simulation conditions and the operating processwere described, and the parameters of each part were configured, making simulationanalysis accurate. Connecting each component of the secondary ion optical system,the whole simulation model of the secondary ion optical system was set up. The massresolution, the variations of the beam diameter and the transmission efficiency, asfunctions of various parameters were studied by adjusting the voltages of the electrodes in lens. Finally, by analyzing the simulation results roundly in detail, thebest combination of electrode voltages in lens of the secondary ion optical system wasdetermined. Through simulation, data recording and data processing function inSIMION software, not only can the secondary ion motion trajectory be viewed, butalso the simulated mass spectrum can be obtained. With stable isotopic ions of copperas the studied objects, simulation research and experimental tests were done. Thesimulation results agreed well with those of the experimental tests, which proved thevalidity of the secondary ion optical system simulation model.