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Laser photodetachment mass spectrometry

Joakim Sandström (Institutionen för experimentell fysik, Atomfysik) ; Pontus Andersson ; Karin Fritioff ; Dag Hanstorp ; R. Thomas ; D.J. Pegg ; K. Wendt
Nuclear Instruments and Methods in Physics Reseach B (0168-583X). Vol. 217 (2004), 3, p. 513-520.
[Artikel, refereegranskad vetenskaplig]

We demonstrate that the technique of laser photodetachment spectroscopy on atomic negative ions can be used as a sensitivity enhancement tool in mass spectrometry, useful for suppressing both isotopic as well as molecular isobaric interferences. In the experiment a beam of negative ions and a laser beam are merged in a collinear geometry and the wavelength of the laser is tuned across the photodetachment threshold region. Due to the large differential Doppler shifts associated with the fast moving ions of different masses, it is possible to selectively detach ions of certain isotopes while leaving others unaffected. By choosing co-propagating laser and ion beams, the heavier isotopes of an element can be selectively detached, whereas counter propagating beams can be used to detach the lighter ones. In this paper we demonstrate the feasibility of the method in an experiment that was designed to selectively detach either 32S− or 34S− ions. The isotopic ratio of 34S/32S was enhanced by a factor of >50 over the natural value. This factor can be improved by using a laser that is better adapted to the measurement and by improving the vacuum conditions in order to further suppress the collisional background. The applicability of this technique to selectivity enhancement in measurements of the abundances of rare or ultra-rare isotopes is discussed.

Nyckelord: Photodetachment, Negative ion, Isotope selectivity, Mass spectrometry

Denna post skapades 2006-08-28. Senast ändrad 2013-07-12.
CPL Pubid: 8874


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Institutioner (Chalmers)

Institutionen för experimentell fysik, Atomfysik (1997-2005)
Institutionen för fysik (GU) (GU)



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