An ion optics for effective ion detection in single particle mass spectrometry

Recently, we reported that significant ion loss occurs prior to detection in conventional single particle mass spectrometry. A more serious type of loss is ion-kinetic-energy-dependent loss. This leads to significant errors in the measured chemical composition of nanoparticles, especially when they have a core-shell structure. In this paper, a novel ion optics for effective detection of ions generated from a single nanoparticle is designed. Using the commercial software SIMION, the trajectories of ions launched at different speeds inside a single particle mass spectrometer are simulated. The effects of changes are investigated with different repelling plates, Einzel lens additions, and substitutions of the tube electrode between extraction and acceleration grids on the ion flight. The best design was found when assembling the trials in the present condition. It was demonstrated experimentally that the new ion optics works well not only in theory, but also in practice.