Isobar suppression in AMS using laser photodetachment
Artikel i vetenskaplig tidskrift, 2008

We are investigating the possibility of using laser photodetachment of negative atomic and molecular ions as an additional isobaric selection filter in accelerator mass spectrometry. The aim of this study is to find a possibility to further improve the detection limit for long-lived heavy radionuclides at AMS facilities. We will focus on the astrophysical relevant radionuclide 182Hf, which is one of the isotopes measured with the 3 MV tandem AMS facility VERA (Vienna Environmental Research Accelerator) at the University of Vienna. Laser-induced isobar suppression is also of importance for radioactive-beam facilities. The present detection limit for measuring the isotope ratio 182Hf/Hf at VERA is 1×10-11. The limiting factor is the strong background of the stable isobar 182W. Currently this background is suppressed using suitable molecular ions in the injection stage. Selective laser photodetachment of the negative ions at the injector can lead to an additional suppression of the interfering isobar. Test experiments have been carried out at the negative ion laser spectroscopy setup at Göteborg University. In a small ion beam apparatus pulsed tunable laser radiation is used to measure the photodetachment cross-section of different atomic and molecular negative ions. We will present studies of the photodetachment process for various tungsten and hafnium molecules with the aim to find a selective isobaric suppression scheme using laser photodetachment spectroscopy in combination with AMS.

Mass spectrometry


Negative ion


O. Forstner

Pontus Andersson

Göteborgs universitet

C. Diehl

R. Golser

Dag Hanstorp

Göteborgs universitet

W. Kutschera

Anton Lindahl

Göteborgs universitet

A. Priller

P. Steier

A. Wallner

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms

Vol. 266 19-20 4565-4568


Atom- och molekylfysik och optik

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