Erlangen 2022 – scientific programme
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MS: Fachverband Massenspektrometrie
MS 4: Accelerator Mass Spectrometry
MS 4.7: Talk
Wednesday, March 16, 2022, 12:15–12:30, MS-H9
Normalization methods for the analysis of environmental 99Tc — •Stephanie Adler, Karin Hain, Martin Martschini, Fadime Gülce, and Robin Golser — University of Vienna, Faculty of Physics
Quantification of the anthropogenic radionuclide 99Tc (t1/2=2.1 · 105 yr) in the general environment by AMS requires suppression of the stable isobaric background of 99Ru and a reliable normalization method to overcome the lack of a stable Tc isotope.
At VERA, previous research has shown that extracting TcF5− from the ion source is suitable for Ion Laser InterAction Mass Spectrometry (ILIAMS) as RuF5− can be suppressed by a laser by up to 105.
Experiments at other AMS-facilities using TcO− normalized the 99Tc to the 93Nb-current of the matrix material with a precision of 30%. Using this approach, our experiments showed Tc-deficits of >40%, indicating major loss of Tc during sample preparation. This lead to thorough investigations of the final target preparation steps utilizing 95Tc and γ-Spectrometry. The chemical recovery was improved to reliable yields >92%, by lowering the calcination temperature.
When extracting 99TcF5− from the source as required for ILIAMS, the Nb-normalization scatters by a factor of 10 and seems less reliable. Thus research on using an alternative spike material 103Rh for normalization is currently ongoing.