On-line HfF5-/WF5- separation in an O2-filled radiofrequency quadrupole gas cell

RATIONALEAn 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 Hf-182 at natural levels by Accelerator Mass Spectrometry (AMS). METHODSThe 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. RESULTSO2 gas was used in the HfF5-/WF5- separation and WF5- was attenuated by nearly 3 orders of magnitude while maintaining similar to 75% transmission of HfF5-. It is expected that the transmission and attenuation can be increased by further research. CONCLUSIONSThis result advances the possibility of detecting natural Hf-182 when AMS is supplemented with an isobar separator in the injection system. Copyright (c) 2013 John Wiley & Sons, Ltd.