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Updated: May 6, 2026

Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
On-line HfF5(-)/WF5(-) separation in an O2-filled radiofrequency quadrupole gas cell
X-L Zhao1, J Eliades, A E Litherland
1Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, ON, K1N 6N5, Canada.
Rationale:
An experimental Isobar Separator for Accelerator Mass Spectrometry (ISAMS) instrument has been used to demonstrate an on-line separation of HfF5(-) from its isobar WF5(-). This is necessary, in addition to sample preparation chemistry, for measuring (182)Hf at natural levels by Accelerator Mass Spectrometry (AMS).
Methods:
The device utilizes a radiofrequency quadrupole (RFQ) controlled gas cell, wherein anion-gas reactions at eV energies attenuate the interfering isobars of the analyte molecular anions, leaving HfF5(-) for AMS analysis. The RFQ also helps to control the multiple scattering resulting from the ion-gas collisions.
Results:
O2 gas was used in the HfF5(-)/WF5(-) separation and WF5(-) was attenuated by nearly 3 orders of magnitude while maintaining ~75% transmission of HfF5(-). It is expected that the transmission and attenuation can be increased by further research.
Conclusions:
This result advances the possibility of detecting natural (182)Hf when AMS is supplemented with an isobar separator in the injection system.
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