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1. Solar System Abundances of the Elements

   https://doi.org/10.1016/B978-0-08-095975-7.00118-2  

   Palme, H.; Lodders, K.; Jones, A. (January 2014, Planets, Asteriods, Comets and The Solar System, Volume 2 of Treatise on Geochemistry (Second Edition). Edited by Andrew M. Davis. Elsevier, 2014., p.15-36)

   Updated solar photospheric abundances are compared with meteoritic abundances. The uncertainties of solar abundances of many trace elements are considerably reduced compared to the 2003 compilation. Some of the solar rare earth elements have now assigned errors of ± 5%, approaching the accuracy of meteorite analyses. The agreement between solar abundances and CI chondrites is further improved. Problematic elements with comparatively large differences between solar and meteoritic abundances are manganese, hafnium, rubidium, gallium, and tungsten. The CI chondrites match solar abundances in refractory lithophile, siderophile, and volatile elements. All other chondrite groups differ from CI chondrites. With analytical uncertainties, there are no obvious fractionations between CI meteorites and solar abundances. Further progress will primarily come from improved solar abundance determinations. The limiting factor in the accuracy of meteorite abundances is the inherent heterogeneity of CI chondrites, primarily the Orgueil meteorite. The interstellar medium (ISM) from which the solar system formed has the same composition as the Sun for volatile and moderately volatile elements within a factor of 2. The more refractory elements of the ISM are depleted from the gas and are concentrated in grains. 

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2. Solar System Elemental Abundances from the Solar Photosphere and CI-Chondrites

   https://doi.org/10.1007/s11214-025-01146-w  

   Lodders, K.; Bergemann, M.; Palme, H. (February 2025, Space Science Reviews)

   Abstract Solar photospheric abundances and CI-chondrite compositions are reviewed and updated to obtain representative solar system abundances of the elements and their isotopes. The new photospheric abundances obtained here lead to higher solar metallicity. Full 3D NLTE photospheric analyses are only available for 11 elements. A quality index for analyses is introduced. For several elements, uncertainties remain large. Protosolar mass fractions are H (X = 0.7060), He (Y = 0.2753), and for metals Li to U (Z = 0.0187). The protosolar (C+N)/H agrees within 13% with the ratio for the solar core from the Borexino experiment. Elemental abundances in CI-chondrites were screened by analytical methods, sample sizes, and evaluated using concentration frequency distributions. Aqueously mobile elements (e.g., alkalis, alkaline earths, etc.) often deviate from normal distributions indicating mobilization and/or sequestration into carbonates, phosphates, and sulfates. Revised CI-chondrite abundances of non-volatile elements are similar to earlier estimates. The moderately volatile elements F and Sb are higher than before, as are C, Br and I, whereas the CI-abundances of Hg and N are now significantly lower. The solar system nuclide distribution curves of s-process elements agree within 4% with s-process predictions of Galactic chemical evolution models. P-process nuclide distributions are assessed. No obvious correlation of CI-chondritic to solar elemental abundance ratios with condensation temperatures is observed, nor is there one for ratios of CI-chondrites/solar wind abundances. 

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3. Solar system abundances and condensation temperatures of the halogens fluorine, chlorine, bromine, and iodine

   https://doi.org/10.1016/j.chemer.2023.125957  

   Lodders, Katharina; Fegley, Bruce (April 2023, Geochemistry)

   We review a large body of available meteoritic and stellar halogen data in the literature used for solar system abundances (i.e., representative abundances of the solar system at the time of its formation) and associated analytical problems. Claims of lower solar system chlorine, bromine and iodine abundances from recent analyses of CI-chondrites are untenable because of incompatibility of such low values with nuclear abundance systematics and independent measurements of halogens in the Sun and other stars. We suspect analytical problems associated with these peculiar rock types have led to lower analytical results in several studies. We review available analytical procedures and concentrations of halogens in chondrites. Our recommended values are close to pre-viously accepted values. Average concentrations by mass for CI-chondrites are F = 92 ± 20 ppm, Cl = 717 ± 110 ppm, Br = 3.77 ± 0.90 ppm, and I = 0.77 ± 0.31 ppm. The meteoritic abundances on the atomic scale normalized to N(Si) =106 are N(F) = 1270 ± 270, N(Cl) = 5290 ± 810, N(Br) = 12.3 ± 2.9, and N(I) = 1.59 ± 0.64. The meteoritic logarithmic abundances scaled to present-day photospheric abundances with log N(H) = 12 are A(F) = 4.61 ± 0.09, A(Cl) = 5.23 ± 0.06, A(Br) = 2.60 ± 0.09, and A(I) = 1.71 ± 0.15. These are our recommended present-day solar system abundances. These are compared to the present-day solar values derived from sunspots of N(F) = 776 ± 260, A(F) = 4.40 ± 0.25, and N(Cl) = 5500 ± 810, A(Cl) = 5.25 ± 0.12. The recommended solar system abundances based on meteorites are consistent with F and Cl abundance ratios measured independently in other stars and other astronomical environments. The recently determined chlorine abundance of 776 ± 21 ppm by Yokoyama et al. (2022) for the CI-chondrite-like asteroid Ryugu is consistent with the chlorine abundance evaluated for CI-chondrites here. Historically, the halogen abundances have been quite uncertain and unfortunately remain so. We still need reliable measurements from large, representative, and well-homogenized CI-chondrite samples. The analysis of F, Br, and I in Ryugu samples should also help to obtain more reliable halogen abundances. Updated equilibrium 50 % condensation temperatures from our previous work (Lodders, 2003; Fegley and Schaefer, 2010; Fegley and Lodders, 2018) are 713 K (F), 427 K (Cl), 392 K (Br) and 312 K (I) at a total pressure of 10^ 4 bar for a solar composition gas. We give condensation temperatures considering solid-solution as well as kinetic inhibition effects. Condensation temperatures computed with lower halogen abundances do not represent the correct condensation temperatures from a solar composition gas. 

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4. Quantifying low fluence ion implants in diamond-like carbon film by secondary ion mass spectrometry by understanding matrix effects

   https://doi.org/10.1039/d0ja00375a  

   Jurewicz, Amy J.; Olinger, Chad T.; Burnett, Donald S.; Guan, Yunbin; Hervig, Richard; Rieck, Karen D.; Woolum, Dorothy S. (January 2021, Journal of Analytical Atomic Spectrometry)

   null (Ed.)

   Minor and trace elements in diamond-like carbon (DLC) are difficult to quantify using SIMS analysis because minor elemental and structural variations can result in major matrix effects even across individual, cm-sized samples. While this material is most commonly used for tribological coatings where minor element composition is not of critical importance, it is being increasingly used in electronic devices. However, it is a unique application that spurred this work: anhydrous, tetrahedrally-coordinated DLC (ta-C) was used as a solar wind (SW) collector material in the Genesis solar-wind sample return mission (NASA Discovery 5). So, for ∼15 years, we have been working on attaining accurate and precise measurement of minor and trace elements in the Genesis DLC using SIMS to achieve our mission goals. Specifically, we have learned to deal with relevant matrix effects in our samples, ion implants into ta-C. Our unknown element for quantification is SW Mg, a low-dose (1.67 × 10 12 at cm −2 ; ∼6 μg g −1 24 Mg), low-energy (∼24 keV average energy) implant; our standard is a high-dose (∼1 × 10 14 at cm −2 of both 25 Mg, 26 Mg) 75 keV laboratory implant for which the absolute 26 Mg/ 25 Mg ratio had been measured to account for variable instrumental mass fractionation. Analyses were performed using O 2 + primary ions having both a low impact energy and a current density of ∼2 × 10 14 ions per cm 2 . Although our unknown was solar wind, the method is applicable to many situations where minor elements in DLC need to be quantified. Recommendations are presented for modifying this data-reduction technique for other SIMS conditions. 

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5. High-resolution Elemental Abundance Measurements of Cool JWST Planet Hosts Using AutoSpecFit: An Application to the Sub-Neptune K2-18b’s Host M Dwarf

   https://doi.org/10.3847/1538-4357/ad61dc  

   Hejazi, Neda; Crossfield, Ian_J M; Souto, Diogo; Brande, Jonathan; Nordlander, Thomas; Marfil, Emilio; Cunha, Katia; Coria, David R; Maas, Zachary G; Polanski, Alex S; et al (September 2024, The Astrophysical Journal)

   Abstract We present an in-depth, high-resolution spectroscopic analysis of the M dwarf K2-18, which hosts a sub-Neptune exoplanet in its habitable zone. We show our technique to accurately normalize the observed spectrum, which is crucial for a proper spectral fitting. We also introduce a new automatic, line-by-line, model-fitting code, AutoSpecFit, which performs an iterativeχ²minimization process to measure individual elemental abundances of cool dwarfs. We apply this code to the star K2-18, and measure the abundance of 10 elements: C, O, Na, Mg, Al, K, Ca, Sc, Ti, and Fe. We find these abundances to be moderately supersolar, except for Fe, with a slightly subsolar abundance. The accuracy of the inferred abundances is limited by the systematic errors due to uncertain stellar parameters. We also derive the abundance ratios associated with several planet-building elements such as Al/Mg, Ca/Mg, Fe/Mg, and (a solar-like) C/O = 0.568 ± 0.026, which can be used to constrain the chemical composition and the formation location of the exoplanet. On the other hand, the planet K2-18 b has attracted considerable interest, given the JWST measurements of its atmospheric composition. Early JWST studies reveal an unusual chemistry for the atmosphere of this planet, which is unlikely to be driven by formation in a disk of unusual composition. The comparison between the chemical abundances of K2-18 b from future JWST analyses and those of the host star can provide fundamental insights into the formation of this planetary system. 

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