Analysis of in situ Nanodiamonds in Organic Matter from Primitive Meteorites with Electron Energy-Loss Spectroscopy and Energy Dispersive X-ray Spectroscopy

Nanodiamonds are present in primitive meteorites at concentrations of up to a few thousand ppm (by mass) However, the origin of these nanodiamonds is controversial. Bulk measurements of noble gases (e.g. Ar, Xe, Kr) and trace elements indicate that they contain nucleosynthetic products of supernovae, yet major element (C and N) isotopic compositions lie within solar system values. Thus, multiple formation environments are possible, including within the early solar nebula, the interstellar medium, or from other stars This uncertainty has been maintained because the isotopic composition of individual ~2 nm nanodiamonds cannot be reliably measured by current methods, although some progress is being made using atom-probe tomography [5,