新型八电极线性离子阱的理论模拟研究

Simulation Study of A New Linear Ion Trap with Octa-electrodes

线性离子阱是目前质谱领域的研究热点之一。为了进一步提升线性离子阱的分析性能以扩大其应用范围,本研究提出一种新型八电极线性离子阱(Octa-electrode linear ion trap,Oe LIT),由8个完全相同的柱状电极和2个端盖电极组成。采用斜边电极结构为例进行研究,配合特定的不平衡射频RF电压施加方式,探究其质量分析性能并实现离子单向出射。利用模拟软件PAN33和AXSIM分析射频电压差Δ和内部电场的关系,得到模拟质谱峰。结果表明,当射频电压差Δ=40%时,斜边八电极线性离子阱获得的质量分辨率最优,m/z 610的离子对应的质量分辨率最高可达3660,与类似结构的三角形电极线性离子阱(Te LIT)的分析结果相比,质量分辨率提高了40%。当Δ=30%时,离子单向出射效率最高可达91%。

Linear ion trap is one hotspot in research of mass spectrometry at present,and a number of linear ion traps with novel structure have been developed so far.To improve the performance of linear ion traps and expand the application,a novel linear ion trap featuring octa-electrodes(OeLIT)was built,which was composed of eight identical columnar electrodes and two end electrodes.This work used the bevel shaped electrodes as an example to investigate mass analysis performance and realize ion directional ejection of OeLIT by applying specific unbalanced RF voltage.The relationship between RF voltage difference ratio(Δ)and internal electric field distribution was studied by software PAN33,and the mass spectra were achieved by AXSIM.It was turned out that the optimal mass resolution of OeLIT at m/z=610 was 3660 when RF voltage difference ratioΔwas 40%.Compared with the performance of triangular-electrode linear ion trap(TeLIT),this result was improved up to 40%.The maximum efficiency of ion unidirectional ejection was up to 91%atΔ=30%.