Studies of anions from sputtering III: The 41K background in measurement by AMS

Zhao, Xiaolei; Eliades, J.; Liu, Q.; Kieser, W.E.; Litherland, A.E.; Ye, S.; Cousins, Lisa M.

doi:10.1016/j.nimb.2009.10.038

Cited by 15 publications

(14 citation statements)

References 11 publications

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“…Early attempts to use the ISA technique with the molecular fluoride anions CaF 3 -and KF 3 -with various reaction gases were only modestly successful [19,14]. For example, in NO 2 , a cell pressure of 1.05 Pa was required for a KF 3 -attenuation of 10 -4 , but this resulted in an attenuation of the analyte CaF 3 -by ~8 x 10 -2 .…”

Section: Measurements With the Isobar Separatormentioning

confidence: 99%

RFQ Reaction Cells for AMS: Developments and Applications

Kieser

Zhao

Litherland

et al. 2013

EPJ Web of Conferences

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Abstract. The use of anion-gas interactions in Radiofrequency Quadrupole (RFQ) ion guide reaction cells has been shown to be very effective in the elimination of a number of atomic and molecular isobars which have caused difficulties for Accelerator Mass Spectrometry (AMS) measurements [1,2]. This presentation begins with a review of the early work leading to the use of ion-gas reactions and continues with a discussion the recent measurements of the efficacy of this technique, some of which involve fluoride molecular anions. However, the transformation of the equipment used for these proof-of-principle measurements into a system suitable for routine analysis has required attention to aspects of the ion beam transport and gas handling subsystems. For example, the cross sections of the ion-gas reactions, involving both the analyte ion as well as the isobar, are critically dependent on the ion energy which has to be reduced from the ion source energy, usually between 20 and 80 keV, to energies typically in the range of several eV, a task complicated by the energy spread and divergence of beams from AMS sputter sources. With simulations using SIMION 8.1 [3] and tests of promising configurations in a laboratory system, principles for the design of the retarder optics have been developed. These are discussed, along with their planned implementation in a next generation analytical system.

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Section: Measurements With the Isobar Separatormentioning

confidence: 99%

RFQ Reaction Cells for AMS: Developments and Applications

Kieser

Zhao

Litherland

et al. 2013

EPJ Web of Conferences

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“…The use of molecular anions containing the analyte element is a useful technique for extending this range [17], but can require additional sample preparation chemistry steps and / or introduce complications in the analysis with additional interferences involving mass, charge and energy in the high energy system [18]. These attributes led to a systematic study of fluoride anions by Zhao et al [21,22,23] in which much of the periodic table is surveyed and in which a systematic variation in the probability of forming fluoride anions from MF n is observed. These attributes led to a systematic study of fluoride anions by Zhao et al [21,22,23] in which much of the periodic table is surveyed and in which a systematic variation in the probability of forming fluoride anions from MF n is observed.…”

Section: Fluoride Matrices For Enhanced Anion Productionmentioning

confidence: 99%

Can-AMS: The New Accelerator Mass Spectrometry Facility At The University Of Ottawa

Kieser¹,

Zhao²,

Clark³

et al. 2011

AIP Conference Proceedings

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The Canadian Centre for Accelerator Mass Spectrometry (AMS) at the University of Ottawa will be equipped with a new, 3 MV tandem accelerator with peripheral equipment for the analysis of elements ranging from tritium to the actinides. This facility, along with a wide array of support instrumentation recently funded by the Canada Foundation for Innovation, will be located in a new science building on the downtown campus of the University of Ottawa. In addition to providing the standard AMS measurements on 14 C, 10 Be, 26 Al, 36 Cl and 129 I for earth, environmental, cultural and biomedical sciences, this facility will incorporate the new technologies of anion isobar separation at low energies using RFQ chemical reaction cells for 36 Cl and new heavy element applications, integrated sample combustion and gas ion source for biomedical and environmental 14 C analysis and the use of novel target matrices for expanding the range of applicable elements and simplifying sample preparation, all currently being developed at IsoTrace. This paper will outline the design goals for the new facility, present some details of the new AMS technologies, in particular the Isobar Separator for Anions and discuss the design of the AMS system resulting from these requirements.

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“…À at an intensity of about 3 Â 10 À4 of KF 2 À (Zhao et al, 2009b) could arise from either its direct production in the ion source, the rare electron decay of the dianion or possibly from the collision of dianions to form anions of the same mass by electron emission. This would be in competition with F À emission, but such studies have not yet been carried out.…”

Section: à2mentioning

confidence: 99%

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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Studies of anions from sputtering III: The 41K background in measurement by AMS

Cited by 15 publications

References 11 publications

RFQ Reaction Cells for AMS: Developments and Applications

RFQ Reaction Cells for AMS: Developments and Applications

Can-AMS: The New Accelerator Mass Spectrometry Facility At The University Of Ottawa

Mass spectrometry with accelerators

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