Correlated Atom-Probe Tomography and Transmission Electron Microscopy of Meteoritic Nanodiamonds

Abstract

Primitive chondritic meteorites contain high concentrations of ~3 nm nanodiamonds (NDs) [1]. NDs are isolated from meteorites by acid dissolution, and these isolates exhibit isotopic anomalies in trace elements, notably Xe, which suggest at least some are presolar in origin [2]. The carbon isotopic composition would provide a better indication of origin, but ND isolates are not pure, containing particles of amorphous, sp2-bonded carbonaceous particles of potentially different origins than the NDs [3]. We are applying atom-probe tomography (APT) to measure the 12 C/ 13 C composition of individual NDs. To identify NDs, it is necessary to confirm the size, density, and structure of the particles in reconstructed APT nanotips [4–6]. Transmission electron microscopy (TEM) is proving increasingly useful for correlated studies of nanostructures and nanoparticles with APT [7–9]. We report the results of correlated TEM/APT studies on two samples containing carbonaceous acid residue from the meteorite Allende.References:[1] Daulton T. L. et al, Geochimica et Cosmochimica Acta 60 (1996), pp. 4853–4872.[2] Lewis R. S. et al, Nature 326 (1987), pp. 160–162.[3] Daulton T. L. et al, J. Quatern. Sci., submitted (2016).[4] Heck P. R. et al, Meteoritics and Planetary Science 49(3) (2014), pp. 453–467.[5] Isheim D. et al, Microscopy and Microanalysis 19(Suppl 2) (2013), CD974–CD975.[6] Lewis J. B. et al, Ultramicroscopy 159 (2015), pp. 248–254.[7] Baik S.-I. et al, Scripta Materialia 68(11) (2013), pp. 909–912.[8] Gorman B. P. et al, Microscopy Today 16(4) (2008), pp. 42–47.[9] Rout S. S. et al. Microscopy and Microanalysis 21(Suppl 3) (2015), pp. 1313–1314.