Improving AMS-chemistry: Two steps forward, one step back

Improving AMS-chemistry: Two steps forward, one step back

Merchel, S.; Bourlès, D. L.; Feige, J.; Ludwig, P.; Pavetich, S.; Ritter, A.; Rodrigues, D.; Rugel, G.; Smith, T.; Ziegenrücker, R.

The DREAMS (DREsden AMS) facility consists of a sophisticated 6 MV accelerator system [1], but also provides two chemistry laboratories for external users. One lab is used for preparation of 10Be, 26Al, 41Ca, 53Mn and 60Fe targets. The other one is dedicated to halide targets (36Cl, 129I), thus, any use of Cl- or S-compounds such as HCl or H2SO4 is strictly prohibited.
Separation protocols are applied to calcite- and quartz-rich samples for in-situ projects [2-4]. Atmospheric 10Be has been leached from marine sediments and Mn-nodules for dating purposes [5] and chemistry refined for bigger samples and heavier nuclides (26Al, 53Mn, 60Fe) [6]. After adapting standard protocols [7] introducing simple Mn-separation by delayed hydroxide separation, higher isobar concentrations (53Cr) have been found asking for further cleaning by ion exchange. With intent to speed-up and simplify the separation procedures for ice and meteorite samples [8], difficulties have been arisen e.g. carryover of Ag+-ions into MnO2, and shortly after overcome. Another chemistry challenge probably mastered is the dissolution of meteoritic troilite (FeS) without losing natCl-carrier before equilibrium with 36Cl, plus suppression of massive isobar amounts. Remaining issues also influencing the quality of AMS-data, such as incorrectly measured stable isotope concentrations (9Be, 27Al), are usually underestimated and harder to tackle.
[1] Akhmadaliev et al., NIMB 294 (2013) 5. [2] Merchel et al., Quat. Geo. 22 (2014) 33. [3] Zech et al., Paleo3 369 (2013) 253. [4] Yildirim et al., Tectonics 32 (2013) 1107. [5] Feige et al., Ludwig et al. & Rodrigues et al., AMS-13. [6] Feige et al., EPJ Web Conf. 63 (2013) 03003. [7] Merchel & Herpers, RCA 84 (1999) 215. [8] Smith et al., AMS-13.

Keywords: accelerator mass spectrometry; cosmogenic radionuclides

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  • Lecture (Conference)
    13th International Conference on Accelerator Mass Spectrometry (AMS-13), 24.-29.08.2014, Aix-en-Provence, France


Publ.-Id: 20131