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