title: Reducing Space Charge Effects in a Linear Ion Trap by Rhombic Ion Excitation and Ejection.
abstract: Space charge effects play important roles in ion trap operations, which typically limit the ion trapping capacity, dynamic range, mass accuracy, and resolving power of a quadrupole ion trap. In this study, a rhombic ion excitation and ejection method was proposed to minimize space charge effects in a linear ion trap. Instead of applying a single dipolar AC excitation signal, two dipolar AC excitation signals with the same frequency and amplitude but 90° phase difference were applied in the x- and y-directions of the linear ion trap, respectively. As a result, mass selective excited ions would circle around the ion cloud located at the center of the ion trap, rather than go through the ion cloud. In this work, excited ions were then axially ejected and detected, but this rhombic ion excitation method could also be applied to linear ion traps with ion radial ejection capabilities. Experiments show that space charge induced mass resolution degradation and mass shift could be alleviated with this method. For the experimental conditions in this work, space charge induced mass shift could be decreased by ~50%, and the mass resolving power could be improved by ~2 times at the same time. Graphical Abstract ᅟ.
authors.affiliation: Department of Chemistry, FUDAN University, Shanghai, 200433, China.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Zhang
authors.affiliation: National Institute of Metrology, Beijing, 100013, China.|School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
authors.forename: Yuzhuo
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Hu
authors.affiliation: School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Guo
authors.affiliation: National Institute of Metrology, Beijing, 100013, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Fang
authors.affiliation: Department of Chemistry, FUDAN University, Shanghai, 200433, China. mfzhou@fudan.edu.cn.
authors.forename: Mingfei
authors.initials: M
authors.lastname: Zhou
authors.affiliation: School of Life Science, Beijing Institute of Technology, Beijing, 100081, China. weixu@bit.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
keywords: Ion trajectory simulation; Linear ion trap; Rhombic ion excitation; Space charge effects