Erlangen 2022 – wissenschaftliches Programm
MS 2.1: Hauptvortrag
Montag, 14. März 2022, 16:30–17:00, MS-H9
Ion Laser InterAction Mass Spectrometry with fluoride molecular anions — •Martin Martschini1, Karin Hain1, Maki Honda1,3, Johannes Lachner2, Oscar Marchhart1, Silke Merchel1, Carlos Vivo-Vilches2, and Robin Golser1 — 1University of Vienna, Faculty of Physics, Austria — 2HZDR, Dresden, Germany — 3NSRC, JAEA, Japan
AMS generally has the best abundance sensitivity for long-lived radionuclides, but the detection of 41Ca, 90Sr, 99Tc, 135Cs and 182Hf in the general environment has been limited or even hampered by strong isobaric interferences. Using molecular fluoride anions, the novel technique of Ion Laser-InterAction Mass Spectrometry (ILIAMS) provides unprecedented isobar suppression for these nuclides of 104-108 inside an RFQ ion guide. Therein, isobaric molecules are efficiently eliminated via laser photodetachment. In addition, molecular interactions with the buffer gas further enhance isobar suppression, e.g. via breakup of KF3− into KF2− + F or via O-pickup of WF5−. Thereby, the VERA-facility has recently achieved the most sensitive detection of 182Hf and 90Sr, the latter at the 15 attogram level. For 41Ca, the blank level with CaF3− and ILIAMS is 41Ca/40Ca = (1.5−1.5+1.7)×10−15. Recent tests also demonstrated that 41Ca can now be measured directly in stony meteorites with sample sizes down to 1-2 mg without performing any chemical preparation, i.e. in the presence of ∼1000 ppm K. This talk will review these benefits of fluoride anions with ILIAMS but also discuss the challenges involved like the strong parasitic ion current and the influence of excited molecules coming from a sputter ion source.