Spontaneous and photo-induced decay processes of WF5- and HfF5- molecular anions in a cryogenic storage ring

• Spontaneous and photo-induced decay processes of HfF5- and WF5- molecular anions were investigated in the Double ElectroStatic Ion Ring ExpEriment (DESIREE). The observation of these reactions over long time scales (several tens of ms) was possible due to the cryogenic temperatures (13 K) and the extremely low residual gas pressure (similar to 10(-14) mbar) of DESIREE. For photo-induced reactions, laser wavelengths in the range 240 to 450 nm were employed. Both anion species were found to undergo spontaneous decay via electron detachment or fragmentation. After some ms, radiative cooling processes were observed to lower the probability for further decay through these processes. Photo-induced reactions indicate the existence of an energy threshold for WF5- anions at about 3.5 eV, above which the neutralization yield increases strongly. By contrast, HfF5- ions exhibit essentially no enhanced production of neutrals upon photon interaction, even for the highest photon energy used in this experiment (similar to 5.2 eV). This suppression will be highly beneficial for the efficient detection, in accelerator mass spectrometry, of the extremely rare isotope Hf-182 using the Hf-182-F-5(-) anion while effectively reducing the interfering stable isobar W-182 in the analyte ion (WF5-)-W-182. The radionuclide Hf-182 is of great relevance in astrophysical environments as it constitutes a potential candidate to study the events of nucleosynthesis that may have taken place in the vicinity of the solar system several million years Published under an exclusive license by AIP Publishing.

Subject headings

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

Keyword

selective laser photodetachment

isobar suppression

amino-acids

ams

dynamics

project

hf-182

ions

gas

Chemistry

Physics

Publication and Content Type

ref (subject category)

art (subject category)