SAMOP 2023 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MS: Fachverband Massenspektrometrie
MS 6: Accelerator Mass Spectrometry II
MS 6.7: Vortrag
Donnerstag, 9. März 2023, 16:00–16:15, F128
Exploring analysis of 99Tc at environmental levels — •Stephanie Adler1, Karin Hain1, Fadime Gülce1, Martin Martschini1, Stefan Pavetich2, Stephen G. Tims2, L. Keith Fifield2, and Robin Golser1 — 1University of Vienna, Faculty of Physics - Isotope Physics, Vienna, Austria — 2Australian National University, Canberra, Australia
Determination of absolute concentrations of the anthropogenic radionuclide 99Tc (t1/2=2.1×105 yr) in environmental samples by AMS requires suppression of the stable isobaric background of 99Ru and a reliable normalization method. At the Vienna Environmental Research Accaelerator (VERA) it was shown that RuF5− can be suppressed by a factor of up to 105 using a laser, making extraction of 99TcF5− a viable option for Ion Laser InterAction MS (ILIAMS). However, none of the methods for the extraction of TcF5− provided a reproducibility better than 50%. Without ILIAMS, the separation of 99Ru from 99Tc is currently only possible at the AMS facility at the Australian National University (ANU), using a 14 MV tandem accelerator. There, 99Ru and 99Tc are separated in an 8-anode ionization chamber owing to minute differences in their energy loss characteristics, observable only at high ion energies. Experiments at the meanwhile shut-down Munich AMS-facility using TcO− and normalization to the 93Nb-current extracted from the sputter matrix showed a precision of 30%. Using this approach at the ANU, a 99Tc dilution series of 1010-107 at/sample was measured in preparation for the measurement of environmental samples, achieving R2=0.993 and a blank level of ∼2×106 at/sample.