Analysis of phase dependent frequency shifts in simulated FTMS transients using the filter diagonalization method
Analysis of phase dependent frequency shifts in simulated FTMS transients using the filter diagonalization method
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DOI：
10.1016/j.ijms.2012.06.010
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发表时间：
2012-07-01
影响因子：
1.8
通讯作者：
Amster, I. Jonathan
中科院分区：
文献类型：
--
作者：
Leach, Franklin E., III;Kharchenko, Andriy;Amster, I. Jonathan
在离子捕获质谱仪中，空间电荷扰动离子运动并影响质量精度。在傅里叶变换质谱（FTMS），离子-离子和离子-图像电荷相互作用已被检查的实验和多粒子离子模拟使用的粒子在细胞（PIC）的方法，所观察到的频率偏移的大小作为离子数的函数与理论模型一致。由于离子-离子相互作用引起的频率偏移通常以时间积分的方式处理，即，对于瞬态信号的持续时间。艾兹科夫和奥康纳通过实验证明，这种相互作用具有时间依赖性，其周期性与同位素峰之间的拍周期相关。在这里，我们调查这样的相互作用，使用PIC模拟和滤波器对角化方法（FDM）获得频率从非常短的持续时间的瞬态。观测到的频率周期性下降与同位素峰的离子云在其回旋加速器轨道中进入相位相关。在轨道阱质量分析器中的离子运动的模拟中观察到类似的现象，对应于同位素组的轴向运动的同相和异相移动。(C)2012 Elsevier B. V.保留所有权利。
Space-charge perturbs ion motion and affects mass accuracy in ion trapping mass spectrometers. In Fourier transform mass spectrometry (FTMS), both ion-ion and ion-image charge interactions have been examined by experiments and by multiparticle ion simulations using the particle-in-cell (PIC) approach, and the magnitude of observed frequency shifts as a function of ion number agrees with theoretical models. Frequency shifts due to ion-ion interactions have generally been treated in a time-integrated fashion, that is, for the duration of the transient signal. Aizikov and O'Connor have experimentally shown that there is a time-dependence for such interactions, with a periodicity that correlates to the beat period between isotope peaks. Here, we investigate such interactions using PIC simulations and the filter diagonalization method (FDM) for obtaining frequencies from very short durations of the transient. Periodic decreases in observed frequency correlate with ion clouds of isotope peaks coming into phase in their cyclotron orbit. A similar phenomenon is observed in the simulations of ion motion in an Orbitrap mass analyzer, corresponding to the axial motion of isotope groupings moving in and out of phase. (C) 2012 Elsevier B.V. All rights reserved.