Diamond xenolith and matrix organic matter in the Sutter's Mill meteorite measured by C‐XANES

Abstract

The Sutter's Mill (SM) meteorite fell in El Dorado County, California, on April 22, 2012. This meteorite is a regolith breccia composed of CM chondrite material and at least one xenolithic phase: oldhamite. The meteorite studied here, SM2 (subsample 5), was one of three meteorites collected before it rained extensively on the debris site, thus preserving the original asteroid regolith mineralogy. Two relatively large (10 lm sized) possible diamond grains were observed in SM2-5 surrounded by fine-grained matrix. In the present work, we analyzed a focused ion beam (FIB) milled thin section that transected a region containing these two potential diamond grains as well as the surrounding finegrained matrix employing carbon and nitrogen X-ray absorption near-edge structure (C-XANES and N-XANES) spectroscopy using a scanning transmission X-ray microscope (STXM) (Beamline 5.3.2 at the Advanced Light Source, Lawrence Berkeley National Laboratory). The STXM analysis revealed that the matrix of SM2-5 contains C-rich grains, possibly organic nanoglobules. A single carbonate grain was also detected. The C-XANES spectrum of the matrix is similar to that of insoluble organic matter (IOM) found in other CM chondrites. However, no significant nitrogen-bearing functional groups were observed with N-XANES. One of the possible diamond grains contains a Ca-bearing inclusion that is not carbonate. C-XANES features of the diamond-edges suggest that the diamond might have formed by the CVD process, or in a high-temperature and -pressure environment in the interior of a much larger parent body.

Controlled ultra-thin oxidation of graphite promoted by cobalt oxides: Influence of the initial 2D CoO wetting layer

“…These three peaks are clearly seen in the spectrum corresponding to the maximum coverage (30 ML), whereas the peak corresponding to the π* states is suppressed. The peak located at 289.2 eV is assigned to the formation of C=O bonds, while the peak located at 288.0 eV is assigned to C-O bonds, in agreement with the literature [35,36,37,38]. In regards to the peak located at 284.5…”

Nanoscale infrared imaging analysis of carbonaceous chondrites to understand organic-mineral interactions during aqueous alteration

“…To obtain molecular structure information at the submicron scale, scanning transmission X-ray microscopy (STXM) combined with carbon X-ray absorption near-edge structure spectroscopy (C-XANES) is so far the most suitable method. The STXM with C-XANES provides molecular structure information at the ∼40 nm spatial resolution and is often applied to various extraterrestrial materials including carbonaceous chondrites (5)(6)(7)(8)(9)(10)(11)(12), Antarctic micrometeorites (13,14), interplanetary dust particles (IDPs) (15,16), and cometary particles recovered from Comet 81P/Wild 2 by the Stardust mission (17)(18)(19)(20).…”

X-ray Absorption Spectroscopy Characterization of a Li/S Cell

“…On cycling, we find: (1) the damping of C π* peak at 288.5 eV and vanishing of the GO σ* peak at 292.0 eV; (2) the increase of the peak at 290.6 eV and peaks B and C at higher photon energies. The peak around 290.6 eV arises from the transition from C 1s to the –C=O π* state [ 25 ], while peaks B and C are associated with the appearance of CO 3 2− [ 26 ]. Therefore, we can conclude that, with cycling, the carbon and graphene structures are highly influenced while the CO 3 2− species accumulates.…”