Detection of ${}^{135}$Cs & ${}^{137}$Cs in environmental samples by AMS

Abstract

The detection of low abundances of ${}^{135}$Cs in environmental samples is of significant interest in different fields of environmental sciences, especially in combination with its shorter-lived sister isotope ${}^{137}$Cs. The method of Ion-Laser InterAction Mass Spectrometry (ILIAMS) for barium separation at the Vienna Environmental Research Accelerator (VERA) was investigated and further improved for low abundance cesium detection. The difluorides BaF${}_2^{-}$ and CsF${}_2^{-}$ differ in their electron detachment energies and make isobar suppression with ILIAMS by more than 7 orders of magnitude possible. By this method, samples with ratios down to the order of ${}^{135,137}$Cs/${}^{133}$Cs $\approx 10^{-11}$ are measurable and the ${}^{135}$Cs/${}^{137}$Cs ratios of first environmental samples were determined by AMS.

We acknowledge funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 101008324 (ChETEC-INFRA)