Optimization of Resonant Excitation Electric Field in Discrete Electrode Printed Circuit Board Ion Trap Mass Analyzer

The printed circuit board ion trap (PCBIT) is a mass analyzer with a unique discrete electrode structure, so the electric fields inside could be flexibly adjusted. Previous researches of PCBIT mainly concentrated on the optimization of the radio-frequency (RF) electric fields, which was usually realized by modifying the geometric parameters or the voltage divided ratio of RF voltage (alpha). In this work, a new method was proposed to further improve the performance of PCBIT. That is, the resonant excitation electric field was optimized in company with the geometric parameters of PCBIT. During the simulation, the geometric parameters of PCBIT were firstly modified to optimize the internal RF electric fields, seeking for greater mass resolution. Then the resonant excitation electric field was optimized by adjusting voltage divided ratio of resonant excitation signal (gamma). And the ion trajectories and simulated mass spectrum were also calculated. The results showed that it could be impossible to improve mass resolution significantly by optimizing the RF electric fields only, while the optimization of resonant excitation field could significantly improve the mass resolution. To achieve great analysis performance, the gamma value should be set up at a relatively low level. For ions at m/z 1891 Da, the optimal mass resolution of over 14500 (FWHM) was obtained in an optimized PCBIT with gamma = 2%, which was much higher than that achieved in traditional optimization methods. This novel method provided a simple and practical approach for developing miniature ion trap mass analyzer with high performance.