Cryo laser-ablation system (157+193nm) with 'triple-quad' plasma mass spectrometer, Cryo-LA-ICPMS/MS

• Subject Area: Geology and Palaeontology
• Term: Funded in 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 515081333

We request funding for a dual wavelength (157+193 nm) cryo-laser-ablation system and a triple quadrupole plasma mass spectrometer, which together will form one analytical device, a cryo-LA-ICPMS/MS, with unique analytical capabilities - in Germany and worldwide. The main innovations of this LA system include a newly-developed large cryo-two-volume LA cell and the combination of two ultrashort excimer laser sources, namely 157 nm wavelength and 193 nm, which can be used alternatively. The ultrashort 157 nm wavelength shows ~10 orders of magnitude better absorption for ice, which significantly improves LA of ice especially with low aerosol concentrations, while the larger LA cell allows investigations of long ice core sections. In combination with the fast washout funnel of the LA cell and high laser frequencies, rapid 2D mapping will be possible. The 'triple quadrupole' plasma mass spectrometer is the other essential component alongside the cryo-LA system. The combination of high sensitivity, unprecedented abundance sensitivity and mass selectivity (e.g. for m/z=87 or 32), as well as fast scanning (>100 µs) through the mass spectrum enables extremely versatile analytical possibilities. The new cryo-LA-ICPMS/MS system opens up an unprecedented array-of research areas: The significantly improved spatial resolution (relative to continuous flow analysis) results in better-than-annual time resolution in deep, thinned ice cores. We plan to systematically elucidate the dynamics of Abrupt Climate Change events in Greenland ice cores (Dansgaard-Oeschger-ev.) via reconstructions of atmospheric (dust) dynamics during cold/warm transitions. Ultimately this should allow us to determine rates of natural climate change. We plan to reconstruct volcanic eruptions and their atmospheric extent (e.g. tropo vs. stratosphere) by means of in-situ sulphur (isotopic) analysis. The behaviour of (dust) aerosols in naturally-recrystallising grains in ice cores, or biological applications on frozen tissue samples are further avenues. In-situ Rb/Sr dating will be a further key development, e.g. applied to metamorphic white mica in matrix vs. inclusions to date prograde metamorphism, or deformation events. Equally, dating of detrital white mica will be used to reconstruct past sedimentary source areas analogous to U/Pb in zircons. Sylvin is an important target for in-situ Rb/Sr dating, as it is relevant for nuclear waste repository design. In-situ U/Th disequilibrium dating, e.g. of late Pleistocene bone or dentin combined with U uptake modelling, is possible via the high abundance sensitivity of ICP-MS/MS. We plan to systematically evaluate comparative 157 nm vs. 193 nm LA for difficult-to-ablate minerals such as sulphates, sylvin, quartz or carbonates. The staff at FIERCE have decades of experience in the design, setup and operation of LA-ICPMS instruments, especially also with cryo-LA and ICP-MS/MS, and are therefore well-placed to implement cryo-157-193 nm LA-ICP-MS/MS.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Cryo-Laser-Ablation gekoppelt an 'Triple-quadrupole' Plasma-Massenspektrometer (cryo-LA-ICP-MS/MS)
• Instrumentation Group: 1700 Massenspektrometer
• Applicant Institution: Goethe-Universität Frankfurt am Main
• Leader: Professor Dr. Wolfgang Müller