¹Karen Valencia,^1,2Aldemar De Moya,^3,4Guillaume Morard,⁵Neil L. Allan,^1,5Carlos Pinilla
American Mineralogist 107, 248–256 Link to Article [http://www.minsocam.org/msa/ammin/toc/2022/Abstracts/AM107P0248.pdf]
¹Departamento de Física y Geociencias, Universidad del Norte, Km 5 Via Puerto Colombia, Barranquilla, Colombia
²Departamento de Ciencias Naturales y Exactas, Universidad de la Costa, Calle 58 No. 55-66, Barranquilla, Colombia
³Sorbonne Université, Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), UMR CNRS 7590, IRD,Muséum National d’Histoire Naturelle, Paris, France
⁴Université Grenoble Alpes, CNRS, ISTerre, F-38000 Grenoble
⁵School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K.
Copyright: The Mineralogical Society of America

Using density functional theory electronic structure calculations, the equation of state, thermody-
namic and elastic properties, and sound wave velocities of Fe3S at pressures up to 250GPa have been
determined. Fe3S is found to be ferromagnetic at ambient conditions but becomes non-magnetic at
pressures above 50 GPa. This magnetic transition changes thec/a ratio leading to more isotropic com-
pressibility, and discontinuities in elastic constants and isotropic sound velocities. Thermal expansion,
heat capacity, and Grüneisen parameters are calculated at high pressures and elevated temperatures
using the quasiharmonic approximation. We estimate Fe-Fe and Fe-S force constants, which vary with
Fe environment, as well as the 56Fe/54Fe equilibrium reduced partition function in Fe3S and compare
these results with recently reported experimental values. Finally, our calculations under the conditions
of the Earth’s inner core allow us to estimate a S content of 2.7wt% S, assuming the only components
of the inner core are Fe and Fe 3S, a linear variation of elastic properties between end-members Fe
and Fe3S, and that Fe3S is kinetically stable. Possible consequences for the core-mantle boundary of
Mars are also discussed.

¹Katarina Kaiser et al. (>10)
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.13784]
¹IBM Research—Zurich, Rüschlikon, 8003 Switzerland
Published by arrangement with John Wiley & Sons

Using high-resolution atomic force microscopy (AFM) with CO-functionalized tips, we atomically resolved individual molecules from Murchison meteorite samples. We analyzed powdered Murchison meteorite material directly, as well as processed extracts that we prepared to facilitate characterization by AFM. From the untreated Murchison sample, we resolved very few molecules, as the sample contained mostly small molecules that could not be identified by AFM. By contrast, using a procedure based on several trituration and extraction steps with organic solvents, we isolated a fraction enriched in larger organic compounds. The treatment increased the fraction of molecules that could be resolved by AFM, allowing us to identify organic constituents and molecular moieties, such as polycyclic aromatic hydrocarbons and aliphatic chains. The AFM measurements are complemented by high-resolution mass spectrometry analysis of Murchison fractions. We provide a proof of principle that AFM can be used to image and identify individual organic molecules from meteorites and propose a method for extracting and preparing meteorite samples for their investigation by AFM. We discuss the challenges and prospects of this approach to study extraterrestrial samples based on single-molecule identification.