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

Zhao, X.-L.; Eliades, J.; Litherland, A.E.; Kieser, W.E.; Cornett, Jack; Charles, Christopher R. J.

doi:10.1002/rcm.6748

Cited by 13 publications

(8 citation statements)

References 21 publications

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“…Di↵erences in electronic structure of anions can also be exploited in anion-gas reactions at eV energies and O 2 was found particularly well suited for HfF 5 -WF 5 separation, providing an isobar suppression of at least 10 3 in an earlier study [25]. While the exact reaction channel remained elusive, Zhao et al [25] argued that HfF 5 , being a superhalogen anion, is extraordinarily stable and, thus, highly immune to electron charge transfer reactions, collisional detachment and association or transformation of molecules at eV energies.…”

Section: Gas Reaction Studiesmentioning

confidence: 85%

The quest for AMS of ¹⁸²Hf – why poor gas gives pure beams

et al. 2020

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The long-lived radioisotope 182Hf (T1/2 = 8.9 Ma) is of high astrophysical interest as its potential abundance in environmental archives would provide insight into recent r-process nucleosynthesis in the vicinity of our solar system. Despite substantial efforts, it could not be measured at natural abundances with conventional AMS so far due to strong isobaric interference from stable 182W. Equally important is an increase in ion source efficiency for the anions of interest. The new Ion Laser InterAction Mass Spectrometry (ILIAMS) technique at VERA tackles the problem of elemental selectivity in AMS with a novel approach. It achieves near-complete suppression of isobar contaminants via selective laser photodetachment of decelerated anion beams in a gas-filled radio-frequency quadrupole (RFQ) ion cooler. The technique exploits differences in electron affinities (EA) within elemental or molecular isobaric systems neutralizing anions with EAs smaller than the photon energy. Alternatively, these differences in EA can also facilitate anion separation via chemical reactions with the buffer gas. We present first results with this approach on AMS-detection of 182Hf. With He +O2 mixtures as buffer gas in the RFQ, suppression of 182WF5− vs 180HfF 5− by >105 has been demonstrated. Mass analysis of the ejected anion beam identified the formation of oxyfluorides as an important reaction channel. The overall Hf-detection efficiency at VERA presently is 1.4% and the W-corrected blank value is 182Hf/180Hf = (3.4 ± 2.1)×10−14. In addition, a survey of different sample materials for highest negative ion yields of HfF 5− with Cs-sputtering has been conducted.

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Section: Gas Reaction Studiesmentioning

confidence: 85%

The quest for AMS of ¹⁸²Hf – why poor gas gives pure beams

et al. 2020

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“…−95 kcal mol −1 . The formation of the dimer coordinated to seven F − ions shows the high affinity of Hf(IV) to fluoride, as demonstrated by the dimeric crystalline structure [Hf 2 F 8 (H 2 O) 6 ], [30] and the resistance of the superhalogen anion [HfF 5 ] − to reactions with O 2 [31] …”

Section: Resultsmentioning

confidence: 99%

“…[29] The formation of the dimeric species (H 3 O) 3 [30] and the resistance of the superhalogen anion [HfF 5 ] À to reactions with O 2 . [31] The (H 3 O) 2 [21] and HfF 4 • 3H 2 O. [30] The anionic species of Hf(IV) did not show the same sequence of thermodynamic stability (Table 3) compared to the species of Zr(IV).…”

Section: Thermodynamic Analysis Of Hf(iv)mentioning

confidence: 94%

Unveiling the Zirconium and Hafnium Speciation in Fluoride‐Nitric Acid Solutions by Paper Spray Ionization Mass Spectrometry Combined with DFT Calculations

et al. 2021

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Paper spray ionization mass spectrometry (PSI-MS) was used to detect a variety of species of hafnium and zirconium present in an aqueous acid solution containing NO 3 À and F À anions. This solution mimetics the acid waters used in separation/extraction processes. Hence, the information provided by PSI-MS is combined with the results achieved from DFT calculations to confirm the nature and stability of each species. In the adopted experimental conditions, Zr(IV) appears coordinated with F À , NO 3 À and H 2 O to generate mainly the dimer [Zr 2 F 3 OH-(NO 3) 2 (H 2 O) 5 ] 2 + , among other complexes, with remarkable thermodynamic stability (À 48.7 kcal mol À 1). On the other hand, Hf(IV) emerges predominantly coordinated with NO 3 À and F À anions. The hafnium monomers [HfF 4 NO 3 ] À and [HfF 3 (NO 3) 2 ] À have thermodynamic stability related to the electron pairing of the valence layer. In the gas phase, the fluoroanions of Zr(IV) demonstrated a high electronic affinity and free energy via DFT (À 156.7 kcal mol À 1) correlating thermodynamic stability to the experimental (À 47 kcal mol À 1), for the formation reaction of [ZrF 5 ] À. Besides, the presence of fluoride and nitrate in the reaction mixture induces the formation of dimers connected in μ 2-F bridges, with coordination 7 and 8 of the central atom. Finally, the results described herein are promising studies of chemical speciation of cationic metals in an aqueous environment, a challenging subject whose importance will grow in the coming years.

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“…In an additional application, Hf and W fluoroanions were generated from the PbF 2 matrix. Since HfF 5 − and WF 5 − were both formed, there was still a problem with overlap of isobaric isotopic ions, which cause interference problems for the measurement of extreme isotope ratios by AMS . However, it was found that the tungsten species could be attenuated by reaction with O 2 or NO 2 , enabling measurement of the trace isotopes of Hf.…”

mentioning

confidence: 99%

Generation of gas‐phase zirconium fluoroanions by electrospray of an ionic liquid

Groenewold

Delmore

Benson

et al. 2014

Rapid Comm Mass Spectrometry

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

Abstract: This result advances the possibility of detecting natural (182)Hf when AMS is supplemented with an isobar separator in the injection system.

Cited by 13 publications

References 21 publications

The quest for AMS of ¹⁸²Hf – why poor gas gives pure beams

The quest for AMS of ¹⁸²Hf – why poor gas gives pure beams

Unveiling the Zirconium and Hafnium Speciation in Fluoride‐Nitric Acid Solutions by Paper Spray Ionization Mass Spectrometry Combined with DFT Calculations

Generation of gas‐phase zirconium fluoroanions by electrospray of an ionic liquid

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

Abstract: This result advances the possibility of detecting natural (182)Hf when AMS is supplemented with an isobar separator in the injection system.

Cited by 13 publications

References 21 publications

The quest for AMS of 182Hf – why poor gas gives pure beams

The quest for AMS of 182Hf – why poor gas gives pure beams

Unveiling the Zirconium and Hafnium Speciation in Fluoride‐Nitric Acid Solutions by Paper Spray Ionization Mass Spectrometry Combined with DFT Calculations

Generation of gas‐phase zirconium fluoroanions by electrospray of an ionic liquid

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

The quest for AMS of ¹⁸²Hf – why poor gas gives pure beams

The quest for AMS of ¹⁸²Hf – why poor gas gives pure beams