Detection of 135Cs & 137Cs in environmental samples by AMS

The detection of low abundances of Cs-135 in environmental samples is of significant interest in different fields of environmental sciences, especially in combination with its shorter-lived sister isotope Cs-137. 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 cesiumdetection. The difluorides BaF2 and CsF2 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 Cs-135,137/Cs-133 ≈ 10^(−11) are measurable and the Cs-135/Cs-137 ratios of first environmental samples were determined by AMS.