It is often stated that ions of the same mass-to-charge do not induce space-charge frequency shifts among themselves in an ion cyclotron resonance mass spectrometry measurement. Here, we demonstrate space-charge induced frequency shifts for ions of a single mass-to-charge. The monoisotopic atomic ion, Cs(+), was used for this study. The measured frequency is observed to decrease linearly with an increase in the number of ions, as has been reported previously for space-charge effects between ions of different mass-to-charge. The frequency shift between ions of the same m/z value are compared to that induced between ions of different m/z value, and is found to be 7.5 times smaller. Control experiments were performed to ensure that the observed space-charge effects are not artifacts of the measurement or of experimental design. The results can be rationalized by recognizing that the electric forces between ions in a magnetic field conform to the weak form of the Newton's third law, where the action and reaction forces do not cancel exactly.

中文翻译：

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傅里叶变换离子回旋共振质谱中相同质荷离子之间空间电荷效应的实验证据

人们常说，在离子回旋共振质谱测量中，具有相同质荷比的离子不会在它们之间引起空间电荷频移。在这里，我们展示了单个质荷比离子的空间电荷引起的频移。本研究使用单同位素原子离子 Cs(+)。观察到测量的频率随着离子数量的增加而线性下降，正如之前针对不同质荷比离子之间的空间电荷效应所报道的那样。将相同 m/z 值的离子之间的频移与不同 m/z 值的离子之间引起的频移进行比较，发现它们小 7.5 倍。进行控制实验以确保观察到的空间电荷效应不是测量或实验设计的人工产物。