Charge ratio mass spectrometry of heavy elements

Kilius, L.R.; Rucklidge, J. C.; Wilson, Graham C.; Lee, H.W.; Chang, Kang‐Tsung; Litherland, A.E.; Kieser, W.E.; Beukens, R.P.; Gorton, Michael P.

doi:10.1016/0168-583x(84)90507-x

Cited by 23 publications

(5 citation statements)

References 18 publications

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“…The energy spectra of molecular anions have been studied in a few cases (Kilius et al, 1984;Gnaser, 1999b;Gnaser, 2000) and in general are not similar to those of atomic anions that are shown in Figure 3. The anions with lower energy than the main peak are associated mainly with molecular anions that decay into smaller mass molecular anions and neutral atoms or molecules, either spontaneously or as a result of collisions with residual gas during ion source acceleration.…”

Section: Molecular Anionsmentioning

confidence: 99%

“…In addition to the continuous energy spread from the ion source there are often small peaks superimposed at other energies (Kilius et al, 1984(Kilius et al, , 1988. These are from the break up of molecular ions after acceleration in the ion source and before entering the next analyzer.…”

Section: The Energy Spectra From the Ion Sourcementioning

confidence: 99%

“…Some of the sharp peaks on the continuum, such as those shown by Kilius et al (1984), are associated with excited molecular anion decay or gas collisions after the ion source acceleration. For example, changes like CH À !…”

Section: Atomic Anionsmentioning

confidence: 99%

“…After electrical retardation, the electron loss during the necessary cooling of the anions to achieve eVenergy is also further complicated by the energy spectrum of the anions from the sputtering process. These energy spreads are in general not well known (Kilius et al, 1984;Gnaser, 1999a,b) although estimates can be made using the theory (Baragiola, 2004) and the limited experimental information. Some indication of the observed energy spread is also given in Figure 3 and discussed further below.…”

Section: The Attenuation Of Anion Isobars By Chemical Reactionsmentioning

confidence: 99%

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Mass spectrometry with accelerators

2010

Mass Spectrometry Reviews

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As one in a series of articles on Canadian contributions to mass spectrometry, this review begins with an outline of the history of accelerator mass spectrometry (AMS), noting roles played by researchers at three Canadian AMS laboratories. After a description of the unique features of AMS, three examples, (14)C, (10)Be, and (129)I are given to illustrate the methods. The capabilities of mass spectrometry have been extended by the addition of atomic isobar selection, molecular isobar attenuation, further ion acceleration, followed by ion detection and ion identification at essentially zero dark current or ion flux. This has been accomplished by exploiting the techniques and accelerators of atomic and nuclear physics. In 1939, the first principles of AMS were established using a cyclotron. In 1977 the selection of isobars in the ion source was established when it was shown that the (14)N(-) ion was very unstable, or extremely difficult to create, making a tandem electrostatic accelerator highly suitable for assisting the mass spectrometric measurement of the rare long-lived radioactive isotope (14)C in the environment. This observation, together with the large attenuation of the molecular isobars (13)CH(-) and (12)CH 2(-) during tandem acceleration and the observed very low background contamination from the ion source, was found to facilitate the mass spectrometry of (14)C to at least a level of (14)C/C ~ 6 × 10(-16), the equivalent of a radiocarbon age of 60,000 years. Tandem Accelerator Mass Spectrometry, or AMS, has now made possible the accurate radiocarbon dating of milligram-sized carbon samples by ion counting as well as dating and tracing with many other long-lived radioactive isotopes such as (10)Be, (26)Al, (36)Cl, and (129)I. The difficulty of obtaining large anion currents with low electron affinities and the difficulties of isobar separation, especially for the heavier mass ions, has prompted the use of molecular anions and the search for alternative methods of isobar separation. These techniques are discussed in the latter part of the review.

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Section: Molecular Anionsmentioning

confidence: 99%

Section: The Energy Spectra From the Ion Sourcementioning

confidence: 99%

Section: Atomic Anionsmentioning

confidence: 99%

Section: The Attenuation Of Anion Isobars By Chemical Reactionsmentioning

confidence: 99%

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Mass spectrometry with accelerators

2010

Mass Spectrometry Reviews

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“…The ions generated in a sputter source leave the source with a distribution in momentum in the 3 spatial dimensions and in energy centered at the principal energy provided by the overall acceleration of the source (Kilius et al 1984(Kilius et al , 1987. Because this energy spread (~50 eV) is small relative to the overall energy of the ion, it is of little significance for normal AMS operations.…”

Section: The Cooling Of CL -Ions In Various Gasesmentioning

confidence: 99%

The Low-Energy Isobar Separator for Anions: Progress Report

et al. 2010

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ABSTRACT. The suppression of interferences from atomic and molecular isobars is a key requirement for the extension of accelerator mass spectrometry (AMS) to the analysis of new cosmogenic isotopes and for increasing the range of applications for small AMS systems. In earlier work, it was shown that unwanted isobars can be eliminated by anion-gas reactions ). Recently, a prototype system in which such reactions could be applied to ions from an AMS ion source, the Isobar Separator for Anions (ISA), was described ). This system decelerates the beam of rare anions from keV to eV energies, guides them through a single radiofrequency quadrupole (RFQ) gas cell, and re-accelerates them for further analysis in a 2.5MV AMS system. Tests of this system with Cl and S anions and NO 2 gas showed a suppression of S with respect to Cl of over 6 orders of magnitude, with a transmission of ~30% for the Cl beam. In this work, results of the analysis of a range of standard reference materials are reported; these show the linearity of the system for measuring the 36 Cl/ 35 Cl ratio over a span of 2 orders of magnitude. Further tests, using the AMS system as a diagnostic tool, have provided clues about the loss of Cl at higher cell pressure and the nature of the residual low level of S transmission. These lead to the assessment of various gases for cooling the Cl -beam. Suppression measurements for 41 K in the analysis of 41 Ca, using NO 2 as a reaction gas, are also discussed. These preliminary measurements have provided data for the development of a more advanced system with separate cooling and reaction cells.

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