Xu Fuxing, Wang Weimin, Jin Liuyu, Qian Bingjun, Ding Chuan-Fan
Key Laboratory of Advanced Mass Spectrometry and Molecular Analysis of Zhejiang Province, Institute of Mass Spectrometry, School of Materials Science & Chemical Engineering, Ningbo University, Ningbo, Zhejiang 315211, China.
Analyst. 2021 Jun 14;146(12):3810-3817. doi: 10.1039/d1an00468a.
The effective electric field radius is a fundamental parameter of ion traps, and it has a significant influence on ion-trapping capability, signal intensity, mass range and some other properties of the ion trap. For a quadrupole ion trap built with ideal hyperbolic electrodes, its effective electric field radius can be obtained by its geometrical size, while it is very difficult to obtain the effective electric field radius for a non-hyperbolic ion trap. In this study, the effective electric field radius of a linear ion trap and some ceramic rectilinear ion traps (cRITs) were investigated via the digital ion trap technology. The dipole frequency of supplementary AC for excitation was locked at a certain value of the main RF trapping wave, and the characteristic q values for excitation could be determined accordingly. The q values could be further used to calculate the effective electric field radius through theoretical calculations. A linear equation had been fitted between the q values for excitation and the square of period T2 through experiments subsequently. The relative deviation between the measured electric field radius and the simulative electric field radius is less than 2%. The simulation results and experimental validation show that the approach has predictive power for modeling and measuring the effective field radius of non-hyperbolic ion traps. It is certainly significant for further understanding the performances of non-hyperbolic quadrupole systems.
有效电场半径是离子阱的一个基本参数，它对离子阱的离子捕获能力、信号强度、质量范围及其他一些特性有显著影响。对于由理想双曲线电极构建的四极离子阱，其有效电场半径可通过其几何尺寸获得，而对于非双曲线离子阱，很难获得其有效电场半径。在本研究中，通过数字离子阱技术研究了线性离子阱和一些陶瓷直线离子阱（cRITs）的有效电场半径。将用于激发的辅助交流的偶极频率锁定在主射频捕获波的某个值上，并据此确定激发的特征q值。通过理论计算，q值可进一步用于计算有效电场半径。随后通过实验拟合了激发的q值与周期T2的平方之间的线性方程。测量的电场半径与模拟的电场半径之间的相对偏差小于2%。模拟结果和实验验证表明，该方法对非双曲线离子阱有效场半径的建模和测量具有预测能力。这对于进一步了解非双曲线四极系统的性能无疑具有重要意义。
