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MS: Fachverband Massenspektrometrie
MS 9: Accelerator Mass Spectrometry and Applications II
MS 9.3: Talk
Thursday, March 9, 2017, 15:00–15:15, RW 2
Improvement of the Laser Ablation Interface for Direct 14C -AMS analysis of carbonates — •Christiane Yeman1, Caroline Welte1, Bodo Hattendorf2, Joachim Koch2, Marcus Christl1, Lukas Wacker1, and Allen Andrews3 — 1Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich, Switzerland — 2Laboratory for Inorganic Chemistry, ETH Zurich, 8093 Zurich, Switzerland — 3NOAA Fisheries, Pacific Islands Fisheries Science Center, HI 96818, USA
A novel method for direct and quasi continuous 14C analysis of carbonates was developed, where a laser ablation (LA) system is coupled to the gas ion source of the MICADAS (MIniCArbonDAtingSystem) accelerator mass spectrometer (AMS) at the Laboratory of Ion Beam Physics, ETH Zurich. By focusing a pulsed laser beam (ArF excimer laser 193 nm, 200 - 250 Hz) on the sample surface, CO2 is produced, which is directly and continuously introduced into the gas ion source and analyzed for radiocarbon. With the new design of the ablation cell and the modified optical setup the energy on the sample is doubled leading to higher CO2 production. Moreover, the spatial resolution has improved from 100µm down to 75µm.
LA-AMS can be used for the analysis of terrestrial and marine carbonate samples, such as stalagmites, corals, shells and otoliths. Here, we present the analysis of the otolith of a red snapper (Lutjanus campechanus) - only a few hundred micrometers thick - by LA-AMS. The 14C signature recorded for the lifespan of the fish shows pre-bomb and peak 14C, indicating the fish was more than 50 years old.