Integrating Ion Beam Control into a Commercial Platform for Improved Multimodal SIMS/MALDI Imaging

Mass spectrometry imaging (MSI) provides spatially resolved chemical analysis of surfaces and is widely applied in biological and biomedical research. Multimodal MSI can combine techniques such as secondary ion mass spectrometry (SIMS) and matrix-assisted laser desorption/ionization (MALDI) to leverage their complementary strengths. However, acquiring multimodal MSI data using separate instruments introduces challenges, including image coregistration and potential sample degradation during transfer. To address these limitations, we previously integrated a C 60 ion gun into a prototype, commercially available MSI instrument, enabling SIMS, MALDI, and secondary electron imaging within a single platform. In this study, we implemented field of view (FoV) mode SIMS on this platform by rastering the ion beam, achieving an improved spatial resolution of 2 μm and surpassing the spatial resolution of the sample stage. Additionally, we optimized the instrument for elemental ion signals and observed enhanced sensitivity of selected species in SIMS through collision-induced dissociation (CID). To explore the usability of the ion gun for high-spatial-resolution image coregistration with other imaging modalities, fiducial markers were etched using the ion gun, creating a localized absence of signal in the etching locations, which can aid coregistration with optical imaging. Additionally, the secondary electrons produced by rastering the ion beam were used to image and assess the MALDI laser focus and power, allowing us to determine the optimal settings.