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Evaluation of Spatial Resolution of Stigmatic Imaging Mass Spectrometrer by Simulation of Ion Trajectories
Stigmatic imaging mass spectrometry (IMS) is a technique used to simultaneously observe the distributions of multiple biomolecules. In stigmatic IMS, large-diameter-laser, about radius 500 µm, is irradiated to a sample and whole ion distribution can be obtained at once. Therefore, the spatial resolution is not limited by laser focusing diameter. However, improvement of aberration of the ion optical system is strongly required for higher spatial resolution imaging. The position of electrodes and voltage applied to the electrodes especially influence ion trajectory. In this study, electrodes of stigmatic IMS in the ion source was constructed by simulation software SIMION8.1. By the development of estimation method for the spatial resolution, it was revealed that ion was not focused on the detector but focused in front of the detector at 0.05–0.25 mm from the center of the detector. The distance from the center got longer, and spatial resolution got lower remarkably. The spatial resolution at 250 µm from the center was 500 times lower than that at the center of the ion optical system.