Rostock 2019 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 9: Resonance Ionization Mass Spectrometry

MS 9.4: Vortrag

Donnerstag, 14. März 2019, 15:00–15:15, U A-Esch 2

Highly selective 2-step ionization schemes for analyis of actinide mixture — •Nina Kneip, Dominik Studer, and Klaus Wendt — Institute of Physics, JGU Mainz

In order to perform ultra trace analysis of radionuclides in environmental samples based on resonance ionization mass spectrometry (RIMS), efficient and highly element-selective laser excitation schemes are required. To analyze different all-relevant actinides within a single sample during one measurement, simple and versatile 2-step ionization schemes were developed at the Mainz Atomic Beam Unit. The use of fully automated grating assisted Ti:sapphire lasers featuring intra-cavity SHG allow for an easy instantaneous change of the ionization scheme and therefore the element of interest during the measurement. The new ionization schemes were tested in synthetic actinide mixture containing actinide cocktails consisting of 10¹⁶ uranium atoms, 10¹² plutonium atoms and 10¹² americium atoms.

Transitions between different quantum states are constrained by optical dipole transition selection rules. Thus, for even isotopes as e.g. ²⁴⁴Pu, with J=0 at the ground state and nuclear spin of I = 0, the J of the final auto-ionizing state was determined using different relative polarization of the incident laser beams. Exploiting this dependence also opens up an additional path to discriminate even Z isotopes against interfering background.