Coupling of imaging NEXAFS with secondary ion mass spectrometry for the chemical and isotopic analysis of presolar cosmic grains

Abstract

We present first results of the combination of imaging photoemission electron spectroscopy with imaging mass spectrometry. Imaging NEXAFS was combined with TOF-SIMS in order to perform a spatially resolved chemical and isotopic analysis of microscopic grain samples. Imaging NEXAFS was used for the nondestructive lateral characterization of mineral phases prior to isotopically resolved mass analysis by imaging TOF-SIMS. This novel approach was demonstrated by performing a chemical and isotopic analysis of the rare presolar grain fraction present in the Murchison meteorite.

Spectroscopic study of impurities and associated defects in nanodiamonds from Efremovka (CV3) and Orgueil (CI) meteorites

“…The NEXAFS information on the chemical bonding and local electronic structure around the absorbing atom is obtained from the spectral X-ray scan. For each step of the Xray energy, a PEEM image was recorded representing the laterally resolved electron emission I(x, y) for a well defined excitation energy E. In this way, a four-dimensional data stack {I(x, y), E} was produced, from which NEXAFS spectra from arbitrary sample areas were extracted by plotting the integrated image intensity I of this specific area versus the photon energy E (Berg et al, 2006). Using the imaging mode the areas with small agglomerates of nanodiamonds where no charging was present were selected and analysed.…”

Atomic spectrometry update. Atomic mass spectrometry

“…Mineral phases of interest, identified by a near edge Xray-absorption fine-structure method were analysed for element ions and isotope ratios with TOF SIMS using a Ga + liquid metal ion gun. 160 Sub-mm resolution could be achieved in the imaging mode. The off-line application was problematical, however, due to the loss of particles, in particular those larger than 10 mm in diameter.…”