Sputtered molecular fluoride anions (M=B, Si, P, K, Ti, In, W, Pb)

Gnaser, Hubert

doi:10.1016/j.nimb.2009.08.018

Cited by 2 publications

(4 citation statements)

References 40 publications

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“…Generally, mass spectra of fluoride samples demonstrate the presence of a rather large variety of atomic and molecular anions in the sputtered flux 10–15. This observation is also corroborated by the mass spectra obtained from the mixed HfWPbF 2 specimen.…”

Section: Resultssupporting

confidence: 60%

“…The theoretical results show that WF 6 features the highest electron affinity ( A ∼ 3.4 eV), in agreement with the experimental finding of WF 6 − being the most abundant anion. In fact, the measured WF n − intensities were found recently14 to correlate exponentially with the theoretical electron affinities. This finding is in agreement with theoretical models of sputtered ion formation that predict an exponential dependence of the ionization probability of atomic anions, P − , on their electron affinity2 …”

Section: Resultsmentioning

confidence: 90%

“…Different possibilities can be envisaged as to how this may happen (see the corresponding discussion in Ref. 14). Eventually, all these processes will result in a stationary state in terms of the relative elemental coverage on the surface.…”

Section: Resultsmentioning

confidence: 99%

“…While the emission of sputtered molecular ions6, 7 is often not appreciated in mass spectrometry as they may cause problems due to mass interferences, thereby limiting the detection sensitivity, some molecular ions were found to be emitted in sputtering with (much) higher abundances than the corresponding atomic ions. This appears to be particularly prominent in the case of negatively charged ions; noteworthy is the very abundant formation of some anionic fluoride molecules from many samples8–15 and their use for analytical purposes. (An extensive review on molecular anions can be found in Ref.…”

Section: Introductionmentioning

confidence: 99%

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Sputtered molecular fluoride anions: HfF_n⁻ and WF_n⁻

Gnaser

Golser

2011

Surface & Interface Analysis

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The emission of negatively charged HfF n − (n ≤ 5) and WF n − (n ≤ 7) molecular ions sputtered from a mixed Hf-W-PbF 2 fluoride sample by a 13 keV Cs + ion beam was studied. The emitted ions were detected in a high-sensitivity double-focusing secondary ion mass spectrometer. In the HfF n − and WF n − series, HfF 5 − and WF 6 − are the anions formed most abundantly, with their ratio amounting to HfF 5 − /WF 6 − ∼6, whereas HfF 5 − /WF 5 − ∼18. In particular, the rather high yield of the HfF 5 − anion could be essential for the sensitive detection of live 182 Hf, a radionuclide (half-live ∼9 million years) that might originate from stellar events in the vicinity of the Earth. Generally, these high ion yields appear to correspond with a high electron affinity of the respective molecule. In addition, their formation may be affected by the atomic composition at the sputtering site. Because their constituents originate from (initially) separated sources (the individual Hf, W and PbF 2 particles), the production of the HfF n − and WF n − molecular anions is envisaged to require an extensive mixing between these different reservoirs during sputtering. Furthermore, the energy distributions of these molecular anion species indicate that they are released from the surface via a collision cascade that also leads to the occurrence of fragmentation processes in the emission event.

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Section: Resultssupporting

confidence: 60%