Stable platinum isotope measurements in presolar nanodiamonds by TEAMS

Abstract

Nanodiamonds are stardust grains commonly found in primitive meteorites. They survived the formation of the solar system and kept their own individuality. Measurements of trace-element isotopic signatures in these grains will help understanding heavy element nucleosynthesis in massive stars and dust formation from their ejecta. We have continued previous attempts to search for stable Pt isotope anomalies in nanodiamonds via trace element accelerator mass spectrometry (TEAMS). The installation of a new injector beam line at the VERA facility allowed studying low traces of stable elements in different materials. Moreover, recent experiments showed that VERA provides the required measurement precision together with a low Pt machine background. Here, we observed for the first time an indication for enhancements of 198Pt/195Pt isotope ratios in two diamond residues prepared by different chemical separation techniques from the Allende meteorite. Variations in other isotopic ratios were within analytical uncertainty, and no anomaly was identified in a third diamond fraction.

GGR Biennial Critical Review: Analytical Developments Since 2010

“…The most common terms for this are Trace Element AMS (TEAMS, e.g., Wallner et al . ) or if the Cs beam is focused and spatial resolution kept, Accelerator‐SIMS or Super‐SIMS (Matteson ). However, mainly due to the background from the ion source, detection limits are not as low for Super‐SIMS as for ‘standard’ AMS, but still some orders of magnitude better than is the case for traditional dynamic SIMS.…”

New Attempts to Understand Nanodiamond Stardust

“…Detailed descriptions can be found in dedicated publications (Besmehn et al 2011;Wallner et al 2011;Farouqi et al 2010). Here we give only a short summary of essentials for this combined study.…”

“…The 4 + state (yield ~ 6%) was selected after charge exchange for detection. A detailed description of the system and more technical details about our measurements can be found in Melber (2011), Wallner et al (2011) and references therein.…”

“…New rprocess calculations for xenon are presented that use updated nuclear physics. Partial or preliminary results of this concerted effort have been communicated in Besmehn et al (2011), Wallner et al (2011) and Ott et al (2009Ott et al ( , 2010.…”

2013 Atomic spectrometry update—A review of advances in environmental analysis

“…A protocol 325 for the accurate determination of 36 Cl included ID for stable Cl measurement and separation from 36 S on a relatively small automated spectrometer using 30 MeV ions. Improvements in AMS measurement precisions and low Pt machine backgrounds contributed to the rst reported observation that the 198 Pt/ 195 Pt ratio in two presolar nanodiamonds 326 from the Allende meteorite may be enhanced by 6-7%. Although they require verication, these results may shed light on nucleosynthesis processes taking place in the parent star.…”