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Downloaded 9/27/2021 10:18:48 AM JAAS TUTORIAL REVIEW View Article Online View Journal | View Issue Isotopes in cosmochemistry: recipe for a Solar System Cite this: J. Anal. At. Spectrom.,2016, 31, 841 Steven Goderis,*ab Ramananda Chakrabarti,c Vinciane Debailled e and Janos´ Kodolanyi´ Extreme isotopic variations among extraterrestrial materials provide great insights into the origin and evolution of the Solar System. In this tutorial review, we summarize how the measurement of isotope ratios can expand our knowledge of the processes that took place before and during the formation of our Solar System and its subsequent early evolution. The continuous improvement of mass spectrometers with high precision and increased spatial resolution, including secondary ion mass spectrometry (SIMS), thermal ionization mass spectrometry (TIMS) and multi collector-inductively coupled plasma-mass spectrometry (MC-ICP-MS), along with the ever growing amounts of available extraterrestrial samples have significantly increased the temporal and spatial constraints on the sequence of events that took place since and before the formation of the first Solar System condensates (i.e.,Ca– Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Al-rich inclusions). Grains sampling distinct stellar environments with a wide range of isotopic compositions were admixed to, but possibly not fully homogenized in, the Sun's parent molecular cloud or the nascent Solar System. Before, during and after accretion of the nebula, as well as the formation and subsequent evolution of planetesimals and planets, chemical and physical fractionation processes irrevocably changed the chemical and isotopic compositions of all Solar System bodies. Since the Received 9th October 2015 formation of the first Solar System minerals and rocks 4.568 Gyr ago, short- and long-lived radioactive Accepted 18th February 2016 decay and cosmic ray interaction also contributed to the modification of the isotopic framework of the DOI: 10.1039/c5ja00411j Solar System, and permit to trace the formation and evolution of directly accessible and inferred This article is licensed under a www.rsc.org/jaas planetary and stellar isotopic reservoirs. Introduction to the Solar System and as well as mixing and sampling of Galactic matter, and thus Open Access Article. Published on 18 February 2016. Downloaded 9/27/2021 10:18:48 AM. represents several billion years of Galactic chemical evolution. Galactic environment Most of the isotopes making up the baryonic matter in our Universe were produced by complex nuclear processes (nucle- As for any good recipe, the right ingredients and perfect timing osynthesis) in specic astrophysical settings, such as the Big are crucial for the preparation of a Solar System capable of Bang and stars (including supernovae). Big bang (primordial) sustaining life. At a distance of 8.33 Æ 0.35 kiloparsecs from the nucleosynthesis, taking place 10 s to 20 min aer the Big Bang, Galactic Center,1 currently at 25 parsecs from the central plane produced most of the universe's 1H, stable helium (in the form of the Milky Way,2 our Sun and associated planetary bodies of 4He) along with small amounts of deuterium (2H or D), and formed 4.567 Gyr3 to 4.568 Gyr4 ago within the Milky Way's 3He and stable lithium-7 (primordially produced radioactive 3H Galactic habitable zone. As a younger generation star in and 7Be decayed to 3He and 7Li). Since the late 50s, stellar a universe of 13.7 Æ 0.2 Gyr,5 the Solar System's chemical and nucleosynthesis in evolving and exploding stars has been isotopic composition is largely the result of nucleosynthesis in known to be the source of all the elements heavier than Li and multiple generations of Milky Way stars, which enriched the Be, and it is considered the main “kitchen stove” preparing the interstellar medium (ISM) with their products of nucleosynthesis, chemical evolution of the Milky Way since its formation.6 Most stars (and their planetary disks), including our Sun, form in groups or clusters of stars in giant molecular clouds, the aVrije Universiteit Brussel, Earth System Sciences, Pleinlaan 2, 1050 Brussels, Belgium. E-mail: [email protected] densest parts of the ISM (e.g., ref. 7). When gravitational bGhent University, Department of Analytical Chemistry, Krijgslaan, 281–S12, 9000 contraction of a localized, dense region of a large interstellar Ghent, Belgium molecular cloud leads to the accretion of a central star, the cCenter for Earth Sciences, Indian Institute of Science, Bangalore, India chemical and isotopic compositions of the surrounding dLaboratoire G-Time, Universit´e Libre de Bruxelles 50, Av. F.D. Roosevelt CP 160/02, rotating disk of gas and ne dust grains will have been inu- 1050 Brussels, Belgium enced by irradiation and inux of matter from older stars.8 For eMax Planck Institut fur¨ Chemie, Hahn-Meitner-Weg 1, 55128 Mainz, Germany This journal is © The Royal Society of Chemistry 2016 J. Anal. At. Spectrom.,2016,31,841–862 | 841 View Article Online JAAS Tutorial Review instance, condensates from supernova explosion ejecta and the precision on the determined isotope ratios, resulting in better winds of late-stage red giant branch (RGB) and asymptotic giant constraints on any recorded mass-dependent and mass-inde- branch (AGB) stars have been found admixed to the Sun's pendent isotope fractionation effects. Although a wide variety of molecular cloud (cf. section on presolar grains). In the Solar instruments exists for specic isotope applications, such as nebula, dust grains will then be heated up, evaporate, condense infrared laser-assisted uorination coupled to stable isotope and aggregate to form km-size bodies called planetesimals. ratio mass spectrometry (IRMS) for high-precision oxygen From that point on accretion progresses, through collisions and isotope analysis, static gas mass spectrometry for noble gas gravitational interactions between planetesimals, leading to the isotope ratio determination and resonance ionization mass formation of a few tens of Moon-to-Mars-sized planetary spectrometry (RIMS) for in situ isotope ratio measurements of embryos in a timeframe of roughly 0.1 to 1 Myr.9 Full planets isobarically interfered species (e.g., ref. 13), the following then form by large-scale collisions between these embryos sections build on the instrumental progress that has occurred within 10 to 100 Myr, and one of these collisions is thought to in the more widely utilized thermal ionization mass spectrom- have led to the formation of the Earth's Moon.10,11 eters (TIMSs), multi collector-inductively coupled plasma-mass spectrometers (MC-ICP-MSs) and secondary-ion mass spec- trometers (SIMSs). Isotope cosmochemistry In terms of precision, TIMS has long set the standard in the Cosmochemistry, oen dened as a subdivision of geochem- isotopic characterization of bulk extraterrestrial samples. A er istry, studies the chemical and isotopic compositions and separation of the elements of interest using ion-exchange history of the Solar System. While astronomical observations as chromatography, the sample is loaded on a lament as a salt, well as robotic and manned orbital and lander probes have which is then heated under vacuum in the source of the mass 14 contributed signicantly to the current understanding of our spectrometer using one, two, or three lament assemblies, Galactic and Solar System neighborhoods, the study of extra- leading to a stable emission of ions, which are detected on an Creative Commons Attribution-NonCommercial 3.0 Unported Licence. terrestrial materials in the form of (micro)meteorites, lunar electron multiplier or Faraday cups. While an electron multi- (e.g., Apollo), asteroidal (e.g., 25143 Itokawa through Hayabusa) plier records the impact of an individual ion by inducing an and cometary (e.g., Wild 2 through Stardust) fragments, inter- electron cascade and is ideally suited for isotope measurements planetary dust particles (IDPs), and samples of the solar wind at low count rates at the cost of precision, Faraday cups detect (e.g., Genesis) has also provided deep insights into Solar System the charges of incoming ions directly and simultaneously, processes, including accurate and precise time constraints on resulting in highly precise isotope ratios. For radiometric dating – – – early Solar System events. The constant growth of meteorite (e.g.,RbSr, U Pb or Sm Nd; Table 2) and planetary reservoir collections worldwide, through systematic hot desert and studies, excellent precision at the level of a few ppm (2 RSD, Antarctic recovery programs, as well as random nds and radar- relative standard deviation) is critical (cf. section on radioactive This article is licensed under a tracking meteorite falls (e.g., Sutter's Mill)12 combined with decay and chronology of the Solar System). Instrumental mass continuous innovations and improvements in the capabilities fractionation is corrected either using internal normalization or – of analytical instruments, aiming at increased precision and by double spiking (e.g., ref. 14 18). In the case of precious or rare samples, however, the lack of sample availability can be an Open Access Article. Published on 18 February 2016. Downloaded 9/27/2021 10:18:48 AM. spatial resolution (cf. below), have made the last few decades an exciting time to unravel the highly complex processes leading to important limiting factor for less abundant elements, for which compositional variability among Solar System objects. Indeed, low ion per atom yields are attained. In addition, the maximum planetary science has undergone a “supernova explosion” over lament temperatures of 2500 C result in the limited ability the last few decades, especially thanks to technological and to ionize elements with high ionization potentials, such as Hf. analytical advances, and this tutorial review summarizes the For those elements, alternative measurement strategies need to be considered, for instance by running the instrument in current state of understanding of the most crucial processes À leading to the chemical and isotopic diversity observed among negative mode (e.g., by measuring Os as OsO3 (ref.
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