半圆弧面线性离子阱性能优化的模拟研究

半圆弧面线性离子阱具有电极结构简单、便于加工和安装精度高等优点。为进一步提升半圆弧面线性离子阱的分析性能,本研究在实验室原有半圆弧面线性离子阱的基础上提出了一种四面开槽的半圆弧面线性离子阱,并对其电极半径与场半径之比r/r0以及离子出射方向上电极的“拉伸”距离进行了优化。模拟结果表明：当r/r0=5：5,离子出射方向上的电极向外“拉伸”0.8~1.2 mm时,离子阱的性能有较大提升,尤其是“拉伸”距离为0.9 mm时所得质量分辨率最高,当扫描速率为409 Da/s时, m/z=609 Da的离子质量分辨率可达到6264( M/△M, FWHM)。作为对比,本研究同时对双曲面线性离子阱的性能进行了仿真优化,结果表明,经过优化后的半圆弧面线性离子阱的性能可与双曲面线性离子阱相媲美。

A Theoretical Study for Performance Optimization of Half Round Rod Electrode Linear Ion Trap

Half round rod electrode linear ion trap ( HreLIT) has many advantages such as simple structure, ease of manufacture and high assembly accuracy. A novel HreLIT with slot on each electrode was proposed to improve the performance of HreLIT. The ratio of field radius and electrode radius ( r/r0 ) and "stretch"distance were optimized to improve the performance of HreLIT. In this study, mass spectrum was achieved by ion trajectory simulation in HreLITs with different geometry and dimension, and mass resolution and ion abundance were used to evaluate the performance of HreLIT. The results showed that the performance of HreLIT with r/r0=5:5 was significantly improved when "stretch" distance ranged from 0. 8 to 1. 2 mm. And the best mass resolution was achieved when the"stretch" distance was 0. 9 mm. When the scan rate was about 409 Da/s, a mass resolution up to 6264 ( M/△M, FWHM) was achieved for ions with m/z=609 Da. For comparison, linear ion trap with hyperbolic electrodes was also simulated and optimized, and it was shown that the performance of optimized HreLIT was equal to that of linear ion trap with hyperbolic electrodes.