Ion Optics Interface for Performing Laser Desorption/Ablation Mass Spectrometry on the Moon
- Room: B304
- Session Number: S14-04
Monday, March 07, 2022: 3:35 PM - 4:10 PM
A compositional analysis of the lunar regolith could provide insight into chemical and isotopic fractionation induced during the formation of the Moon and into the distribution of viable economic resources such as water and/or valuable metal assets. Laser desorption/ablation mass spectrometry is able to desorb thermal-labile species with large enthalpies of vaporization that would degrade before being volatized by pyrolysis and is well suited to such chemical analysis. Transmitting ions into a mass analyzer requires careful control of the electric fields at that interface. Recently designed instruments for planetary exploration have utilized comminutors, drills, or other mechanisms to produce fine powders that can be collected in a metal cup or sample tray that is set to a desired voltage to optimize ion transfer. In this study, we propose a simpler approach that only requires that the instrument be placed into contact with the planetary surface.
An ion optics interface has been designed that simulations show enables excellent transmission of ions even while rastering of the laser across a 0.5 x 0.5 mm field of view and accounting for up to 33% penetration of regolith into the aperture. Furthermore, the ability to tune key voltages in the interface enables compensation for electric potential variation within the sample depending on its electrical permittivity.
Testing of the newly developed interface with a Orbitrap analyzer modified for spaceflight is underway. A prototype instrument using a metal target with samples with varying permittivity and thickness deposited on it via the dried-droplet method has been used to demonstrate mass resolutions of m/delta m > 100,000 and < 3 ppm mass accuracy.
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Keywords: Please select up to 4 keywords ONLY:
Instrumentation,Laser Desorption (MALDI),Mass Analyzers,Method Development