Köln 2025 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 8: Accelerator Mass Spectrometry I

MS 8.3: Vortrag

Donnerstag, 13. März 2025, 16:30–16:45, HS 2 Chemie

Exposure dating using AMS of ³⁶Cl isotopes in CaSO₄ -containing sediments and evaporites — •Natasha Goaba Kalanke¹, Markus Schiffer², Erik Strub³, Gregory Campbell Hillhouse¹, Michael Staubwasser⁴, Steven Binnie⁴, and Dennis Muecher² — ¹Department of Physics and Astronomy, Botswana International University of Science and Technology — ²Institute of Nuclear Physics, University of Cologne — ³Institute of Nuclear Chemistry, University of Cologne — ⁴Institute of Geology and Mineralogy, University of Cologne

The cosmogenic nuclide ³⁶Cl is valuable for exposure dating due to its long half-life of 3.013E5 years, enabling accurate geochronological timelines. This study measures isotopic ratios of ³⁶Cl, ³⁵Cl and ³⁷Cl focusing on under-utilized gypsum (CaSO₄.2H2O) due to overlapping isotopic mass interference from ³⁶S. We are developing a novel chemical preparation method to suppress isobaric ³⁶S and enhance chlorine yield as AgCl(∼80-90%), validated by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). The Anion Laser Isobar Separator (ALIS), employs laser photo-detachment principles for isobar suppression and ³⁶Cl transmission. Furthermore, ions are cooled within an advanced radiofrequency quadrupole (RFQ) system with a high-power 532 nm continuous-wave laser (>10 W). Initial ALIS transmission measurements with chemically optimized samples will be presented, along with the chemical protocol, and integration of ALIS to a 6 MV Tandem accelerator for improved ion beam emittance and superior isobar suppression.