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MS: Fachverband Massenspektrometrie
MS 9: Resonance Ionization Mass Spectrometry
MS 9.5: Vortrag
Donnerstag, 14. März 2019, 15:15–15:30, U A-Esch 2
TOF-SIMS and resonant laser-SNMS analysis for isotope ratio measurements on insulators — •Hauke Bosco1, Martin Weiss1, Manuel Raiwa1, Klaus Wendt2, and Clemens Walther1 — 1Institute of Radioecology and Radiation Protection, Leibniz University Hannover — 2Institute of Physics, Johannes-Gutenberg University Mainz
Radionuclides can interact with natural minerals via, e.g., sorption or incorporation. It is a key interest of radioecology to determine binding strengths and preferred sorption sites. Static SIMS is a well-suited and quasi non-destructive technique for measuring these properties by imaging spatial correlations of radionuclides with different mineral phases. By bombarding the surface with highly energetic ions, atomic and ionic fragments are ejected from the surface. The composition and distribution of isotopes is analyzed subsequently by MS. Isobaric interferences, however, can hinder precise isotope identification, as is the case for Pu-241 and its radioactive daughter isotope Am-241. Instead of analyzing the sputtered secondary ions, the secondary neutrals are resonantly post ionized by absorbing the light of precisely tuned lasers, selecting one element only (so called resonant laser secondary neutral mass spectrometry, rl-SNMS). While the spatial resolution of the sputter process of typically down to 70 nm is retained, isobaric interferences can be suppressed by several orders of magnitude. However, many of the samples of interest, e.g. the aforementioned minerals, are non-conducting, causing surface charging during the analysis. At the IRS such a setup has been developed and successfully tested.