Multimodal Stigmatic Imaging Mass Spectrometry with Flat-Top Laser Probe

Forensic analysis of particles of special nuclear materials found in the air, soil, water, or sediments is used to determine crucial information about compliance of nations with processing of nuclear materials. Multiple analytical techniques are needed to reach high certainty conclusions in a short timeframe but means of combining these techniques has heretofore been disjointed. This project seeks to develop a unified characterization approach of high sensitivity and rapidity that incorporates multiple inputs for enhanced certitude of the outcome. Steam Instruments, Inc. will develop a new class of instruments for multi-modal surface microanalysis. Optical microscopy will be enabled by an in-vacuum Schwarzschild microscope incorporated in the charged particle optics of the instrument. A novel imaging mass spectrometer will be uniquely capable of ion microscopy in stigmatic imaging mode enabled by the combination of a flat-top laser probe with a position-sensitive ion detector. The time-of-flight mass spectrometer (TOF-MS) analyzer will be based on a linear configuration enhanced by the patent- pending Pulsed Deflection Lens (PDL-MS) technology developed by Steam Instruments. This approach will enable very rapid acquisition (<1 hour) of very high resolution (200 nm) 2D isotopic maps over 1 cm2 areas with exact registry with a submicron resolving collinear light microscope. 3D isotopic mapping may also be performed with sub-nm depth resolution. In Phase I, the principal risk for Steam Instruments to develop this new instrument, development of an achromatic laser objective optics integrated with our ion extraction electrodes, will be retired. This Schwarzschild objective will be designed by an expert in reflective optics and the configuration will be tested by simulations for compatibility with our ion extraction optics. Once fabricated, the optics will be assembled, alignment procedures will be tested in air with lasers and the light optical performance against specifications for the commercial instrument will be assessed. Mass spectrometry typically can be the highest analytical sensitivity technique available. Yet, the only commercial mass spectrometry techniques for imaging analysis of inorganic materials operate at low speed and modest analytical sensitivity. The instrument we will develop makes major improvements on both fronts. The anticipated detection limits for elemental analysis will be approaching single atomic parts-per-billion (ppb or ng/g). If needed for improved characterization of special nuclear material samples, resonant laser post-ionization (such as RIMS) can be incorporated in this instrument at a later stage (Phase III) to dramatically improve its sensitivity (×1000, into the single part-per-trillion range). The instrument will also produce mass spectrometric images about 10,000 times faster. This combination of properties is expected to foster adoption in fields such as nuclear forensics, geological and environmental sciences, and materials science.