The electronic structure of and

The electronic structure of HfF 5 - , WF 5 - and the related species HfFn and WFn is studied using ab initio methods. Computation reveals that the hafnium fluorides are much more stable than the corresponding tungsten fluorides. The detachment energy of HfF 5 - is 8.8 eV, whereas the corresponding quantity of WF 5 - is only 3.9 eV. These results show that WF 5 - can be photodetached while HfF 5 - is unaffected, and so it is possible by using photodetachment to suppress the interfering isobar 182W in the ion beam of 182Hf. Such information is the precondition for the successful implementation of a future photodetachment process in Accelerator Mass Spectrometry.