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PCA ETR:REVIEW FEATURE: SPECIAL

Laboratory technology and

Ernst K. Zinnera,1, Frederic Moynierb, and Rhonda M. Stroudc aLaboratory for Space Sciences and Department, and bDepartment of and Planetary Sciences, Washington University, St. Louis, MO 63130; and cMaterials Science and Technology Division, Code 6360, Naval Research Laboratory, Washington, DC 20375

Edited by Mark H. Thiemens, University of California at San Diego, La Jolla, CA, and approved March 14, 2011 (received for review October 12, 2010)

Recent developments in analytical instrumentation have led to revolutionary discoveries in cosmochemistry. Instrumental advances have been made along two lines: (i) increase in spatial resolution and sensitivity of detection, allowing for the study of increasingly smaller samples, and (ii) increase in the precision of isotopic analysis that allows more precise dating, the study of isotopic heterogeneity in the , and other studies. A variety of instrumental techniques are discussed, and important examples of discoveries are listed. Instrumental techniques and instruments include the microprobe, ablation gas MS, Auger EM, ionization MS, accel- erator MS, transmission EM, focused ion-beam , probe tomography, X-ray absorption near-edge structure/ loss near-edge , Raman microprobe, NMR spectroscopy, and inductively coupled MS. | extraterrestrial

osmochemistry is concerned with work of this paper. In our treatment, reader is referred to a special issue of the study of the Solar System we will emphasize the impact of instru- and (11) that (SS), its formation, its history, mentation on cosmochemistry. This will is devoted to the analysis of re- and the processes that shaped exclude many conventional techniques, turned by the mission. theC planets. This is mainly accomplished such as X-ray analysis in the electron In the following, we will shortly describe through the analysis of extraterrestrial microprobe and SEM, activation various instrumental techniques and dis- samples, astronomical observations from analysis, conventional X-ray fluorescence, cuss important results obtained by their Earth and space, and in situ measurements and X-ray diffraction analysis, which are application. by robotic spacecrafts. The latter is the important to cosmochemistry but are dis- topic of a separate chapter; this chapter cussed extensively elsewhere. Ion Microprobe is concerned with the question of how Recent progress in instrumental devel- The ion microprobe has become the most recent advances in laboratory instrumen- opments has mainly been made along two important instrument for the isotopic tation have led to revolutionary discover- lines. analysis of small samples (12, 13). It uses ies in cosmochemistry. i) Increase in spatial resolution and sen- SIMS. In this technique, a primary ion The study of extraterrestrial samples – sitivity of detection, allowing for the beam (O or Cs) of typically 15 20 keV includes the analysis of (from energy is focused into a small spot onto the study of increasingly smaller samples asteroids, , and the Moon), lunar sample. Of the sputtered by the such as IDPs, stellar condensates samples (returned by Apollo), micromete- primary beam bombardment, a certain orites (1), interplanetary dust particles (), and returned mate- fraction (the ionization efficiency strongly (IDPs) (2, 3), samples returned from rial from the Stardust and Genesis depends on the element) is emitted as , (Stardust) (4), asteroids (HAY- missions. Examples of instruments in- and these secondary ions are analyzed in ABUSA) (5), and samples from the clude the transmission EM (TEM), (Genesis) (6). a double-focusing magnetic sector secondary ion MS (NanoSIMS), reso- Throughout the 20th century, continu- either by single ion counting ous development of analytical instrumen- nance ionization MS (RIMS), Auger in electron multipliers or by charge mea- tation has led to a deep understanding of probe, atom probe, and surement in Faraday cups (FC). fl how the SS formed, what material con- X-ray uorescence (μ-XRF). One of the major applications of the ion tributed to its formation, what processes ii) Increase in the precision of isotopic microprobe is the isotopic analysis of took place in its early history, and what was analysis that allows for more precise presolar grains (14, 15). These grains, the time scale. An important step in the dating, the study of isotopic heteroge- found in primitive meteorites, are bona fi development of instrumental capabilities neity in the SS, and other studies. An de stardust. They condensed in the ex- was the Apollo Program. Funding for in- example is multicollector inductively panding atmospheres of late-type [red giant branch (RGB) and asymptotic strumentation for the analysis of returned coupled plasma MS (MC-ICP-MS). lunar samples led to analytical advances giant branch (AGB) stars] and in the that, in turn, resulted in pathbreaking In some cases, one can achieve both high ejecta from supernova (SN) explosions. discoveries in other fields. Examples are precision at fairly high spatial resolution. They carry the isotopic compositions of the discovery of 16O excesses in Ca-Al– Examples are ion microprobe analysis of their stellar sources and thus, give infor- rich inclusions (CAIs) (7) and evidence the Al-Mg system and O-isotopic meas- mation about stellar nucleosynthesis and for the initial presence of 26Al in the urements of and CAIs with the isotopic evolution of the Galaxy. The early SS (ref. 8; see also ref. 9). large-sector ion microprobes and Faraday ion microprobe makes it possible to The last two decades have seen a pleth- cup detection. ora of instrumental developments that The small amounts of material returned have led to revolutionary discoveries. The by the Stardust and Genesis missions have Author contributions: E.K.Z., F.M., and R.M.S. analyzed whole field of the analysis of extraterres- not only provided motivation to try new data and wrote the paper. trial materials has grown to an extent analysis and sample handling (10) techni- The authors declare no conflict of interest. and involves so many different analytical ques but have fostered collaborations and This article is a PNAS Direct Submission. techniques that a detailed survey is com- combination of a multitude of different 1To whom correspondence should be addressed. E-mail: pletely out of the question in the frame- analytical instruments. As an example, the [email protected]. www.pnas.org/cgi/doi/10.1073/pnas.1015118108 PNAS | November 29, 2011 | vol. 108 | no. 48 | 19135–19141 measure isotopic ratios in presolar grains (silicates and SiC). The last study (23) is the discovery of a reservoir extremely en- down to less than a micrometer in diameter. especially interesting, because in addition riched in 17O and 18O in the early SS (31). A considerable advance in the study of to the NanoSIMS, it applies the TEM, The MegaSIMS combines SIMS and small grains has been brought about by Raman microprobe, and X-ray absorption accelerator MS (AMS). Its main design a new type of ion microprobe, the Nano- near-edge structure (XANES; see below) characteristic is not high lateral spatial SIMS (16). This instrument is character- to the analysis of IDPs believed to have resolution but high depth resolution and ized by a small primary beam spot (down originated from the 26P/Grigg- utmost sensitivity (32, 33). It was especially to 50 nm for Cs), high secondary ion Skjellerup. built for the isotopic analysis of transmission at high mass resolution The ion microprobe has also been im- N and O implanted into samples exposed (needed for separation of atomic ions portant in the analysis of material returned during the Genesis mission (6). Because from molecular interferences), and up to from the comet Wild 2 by the Stardust solar wind ions are implanted at shallow seven detectors. The NanoSIMS has mission. The NanoSIMS was used to depth and low fluence, high depth resolu- played an essential role in the discovery of identify true O-rich stardust material in tion and sensitivity are extremely impor- presolar silicates (17, 18). Although pre- impact craters on Al foil (24) and a pre- tant. MegaSIMS analysis of Genesis solar silicates in primitive meteorites are solar SiC grain in an aerogel capture samples has established the N- and O- more abundant than other presolar grain (25). Ion microprobe isotopic isotopic compositions of the Sun (34, 35). species such as SiC, graphite, corundum, analysis of Inti, a refractory inclusion Both have been the topic of intense debate and spinel (14, 15), presolar silicates are captured by Stardust, showed a 16O-rich for decades (36, 37). small (typically 250–300 nm in diameter) composition (26), confirming its similari- Gas MS and have to be detected in the presence of ties to CAIs. The presence of a refrac- ’ an overwhelming number of isotopically tory inclusion formed in the inner SS in The Sun s N-isotopic composition ob- normal silicates of SS origin. This makes it a comet from the indicates tained with the MegaSIMS agrees with necessary to measure the isotopic compo- mixing of material from the inner to the that obtained by laser ablation gas MS (LA-GMS), where the solar wind-im- sitions of thousands and tens of thousands outer solar nebula. Another piece of evi- of grains, achieved by isotopic raster im- planted N was excavated layer by layer by dence confirming mixing was obtained by aging. Fig. 1 shows O-isotopic ratio images UV laser pulses (38). This technique was the ion-probe analysis of -like of a 10- m × 10- m area covered with also used for the analysis of noble gases in μ μ objects in cometary material from - small grains from the Acfer 094 primitive Genesis samples (39). If differs from IR dust, which had O-isotopic compositions (18). One grain is identified laser bombardment, where sample heating similar to those of chondrules from car- by its anomalous isotopic compositions leads to the release of noble gases and 17 18 bonaceous chondrites (27). (excess in O and deficit in O). Its where no depth profiles can be obtained. With large-radius ion microprobes and enlarged SEM image is also shown. An example is the analysis of He and Ne in multidetection with FC, a precision Isotopic imaging in the ion microprobe cometary from Stardust (40). has been used for the detection of rare approaching that of thermo-ionization grain types such as SiC grains of type (TIMS) or inductively Auger EM X, which have 28Si excesses, indicating coupled plasma-source MS equipped with Although the electron beam used for X-ray an SN origin (19). Even rarer are SiC multiple collectors (MC-ICP-MS) has been analysis in the electron microprobe or grains with large 29Si and 30Si excesses, achieved, whereas the primary beam di- SEM can be focused into a very small spot also believed to have an SN origin. Recent ameter is still only ∼25 μm (28). Such of only a few nanometers, the size of the measurements on chondrules have estab- automatic imaging with the NanoSIMS 26 volume from which X-rays are emitted is identified such grains, and their isotopic lished that Al was uniformly distributed typically 1 μm in size. This is much larger ratios provide information on SN nucleo- in the early SS, which can be used as than the typical size of presolar silicate fi synthesis (20). a ne-scale chronometer for early SS grains identified by isotopic imaging in the Isotopic raster imaging in the NanoSIMS events (28, 29). A noteworthy technical NanoSIMS. Auger , in contrast, has identified D- and 15N-rich hotspots, advance with large-radius ion microprobes are detected only from the top few nano- small areas with extremely large D and 15N that have direct ion imaging capability, meters of the sample and can be used for excesses in organic matter from primitive such as the Cameca ISM 1270/1280, has elemental analysis on this spatial scale meteorites (21) and in primitive IDPs (22, been the stacked CMOS-type active pixel (41, 42). Thus, Auger EM (AEM) is the 23). These excesses indicate the presence sensor (SCAPS). This device allows one to ideal complement to the NanoSIMS for of material from the presolar molecular obtain high-spatial resolution isotopic im- the in situ elemental analysis of sub- cloud. Primitive IDPs not only have hot- ages with high sensitivity. It has not only micrometer grains. spots but also bulk enrichments in 15N as been successfully used in the search for well as high abundances of presolar grains presolar silicates (30), but it has also led to RIMS One of the limitations of SIMS is that, generally, it cannot separate isobaric interferences (e.g., 92Zr from 92Mo). One of the great advantages of RIMS is that it uses a finely tuned laser beam to selec- tively ionize the neutral atoms of a given element sputtered from the sample by an ion beam or desorbed by a laser pulse (43, 44). These ions are then analyzed for their in a time of flight (TOF) mass spectrometer. The other advantage is that Fig. 1. Isotopic ratio images of O calculated from isotopic raster images obtained with the NanoSIMS. a large fraction (up to 50%) of the atoms An enlarged SEM picture of a presolar silicate identified from the isotopic images is also shown. Mod- released from the sample can be ionized ified from Nguyen and Zinner (18). and detected.

19136 | www.pnas.org/cgi/doi/10.1073/pnas.1015118108 Zinner et al. These features have been used to mea- pounds in cometary samples from Stardust circumstellar dust condensation conditions sure the Mo- and Zr-isotopic compositions (52), similar to what is observed in IDPs. including , pressure, order of of presolar SiC grains (45). Fig. 2 shows This finding is consistent with the belief phases condensed, and deviations from the Mo-isotopic patterns of two presolar that some IDPs have a cometary origin. thermodynamic equilibrium (55–58) SiC grains, identified by their C-, N-, and (Fig. 3). For SS materials, such as the Si-isotopic ratios as originating from an AMS Stardust comet Wild 2 samples, TEM data AGB star (mainstream grain) and a su- In AMS, negative ions typically produced regarding crystallinity and the presence pernova (type X grain) (46). The patterns by sputtering are accelerated to energies of of subgrains inform our understanding of of these two grains are completely differ- a few MeV and sent through a stripping both nebular condensation conditions ent, indicating different nucleosynthetic foil or gas cell, which turns them into and radial transport processes (4, 59). processes (s process and neutron pulse, positive ions that subsequently go through Signatures of shock as well as thermal, respectively). Another important RIMS a magnetic sector mass spectrometer. The aqueous, and processing can all result is the identification of the initial outstanding characteristic of this tech- be identified. As the quality of electron presence of 99Tc in presolar SiC grains nique is the extreme sensitivity to rare and stability of the electron emitters (47). The detection of Tc, which does (radioactive) in the presence of in transmission electron has not have any stable isotopes, in stars (48) high abundances of other (stable) iso- improved, the ability to detect ever more played an important role in the history topes. One of the most exciting discoveries subtle processing signatures has also im- of the theory of nucleosynthesis (49). by AMS is the detection of the radioiso- proved. Field emission sources, aberration- tope 60Fe in deep-sea samples deposited corrected lenses, and monochromation Microprobe Two-Step Laser MS 2.8 Myr ago (53). This finding indicates now permit detection of signatures as A variation of RIMS that is applied to the a nearby SN explosion a few million minute as single-atom impurities in some analysis of organic is microprobe years ago. cases (60, 61). two-step laser MS (μL2MS). In this tech- nique, a whole family of organic com- TEM Focused Ion-Beam Microscopy pounds desorbed from the sample with TEM enables analysis of grain structure, Focused ion-beam microscopy (FIB) a pulsed IR laser beam is ionized reso- elemental composition, and local bonding addresses the need to prepare TEM nantly by a UV laser beam. For example, at scales ranging from micrometers to samples of very heterogeneous materials UV with a of 266 nm subnanometers. TEM images are formed (e.g., sections of chondrite or rims results in electronic excitation of the aro- from electrons transmitted through a thin associated with chondrules and CAIs) matic ring so that aromatic compounds sample (<200 nm) illuminated with high- (62, 63) and/or isotopically anomalous or can be selectively ionized in this way. The energy electrons (usually 200 or 300 keV). otherwise unique grains ranging in size detailed masses of these compounds are The contrast in a given image depends from microns to submicrons (56, 64). The determined in a TOF mass spectrometer. on the electron beam illumination con- FIB is similar to an SEM with a Ga+ ion This techniques has led to the identifica- ditions (e.g., parallel or focused probe) beam in place of the electron beam (FIB) tion of polycyclic aromatic hydrocarbons and the selection of transmitted electrons or in combination with an electron beam (PAHs) and alkylated derivatives in IDPs that have undergone specific kinds of in- (FIB-SEM) (65). The user controls the (50) and PAHs in presolar graphite grains teractions with the sample (e.g., diffrac- Ga+ beam current and raster pattern to (51). Recently, it has resulted in the tion, high-angle scattering, or inelastic remove sample material by sputtering and identification of N-rich aromatic com- scattering). The most common types of TEM images in cosmochemistry studies are bright-field TEM (BF-TEM) for determination of microstructure, high- resolution TEM (HR-TEM) for imaging of lattice structure and atomic planes, se- lected area electron diffraction (SAED) for determination, scan- ning TEM annular dark field (STEM- ADF) for atomic number contrast, and energy loss-filtered TEM (EF-TEM) for elemental mapping. In addition to imag- ing, TEM analysis often includes two types of spectroscopy: energy dispersive X-ray spectroscopy (EDX) and electron energy loss spectroscopy (EELS); both provide elemental composition data, and in the latter case, they also provide information about bond configurations and oxidation states. More details of these techniques Fig. 3. Scanning TEM annular dark-field (STEM- can be found in Williams and Carter (54). ADF) image of a type-Z presolar SiC grain. The Applications of EELS are also discussed grain was first isolated from the host meteorite by herein along with the related synchrotron- physical disaggregation and then, was sectioned based XANES analysis. by focused ion-beam microscopy to form an elec- The structural and chemical data ob- tron transparent section (123). The STEM-ADF image reveals a crack that extends from the grain tained from TEM have fundamentally surface into the interior as well abundant sub- Fig. 2. Molybdenum isotopic patterns measured changed our understanding of the con- grains. Energy dispersive X-ray spectroscopy (EDX) by RIMS in two different presolar SiC grains. The ditions of formation and alteration of SS shows that the crack is oxidized and that the C-, N-, and Si-isotopic ratios of these grains are and extrasolar materials. Studies of pre- subgrains include multiple phases, some rich in Fe also given. Modified from Pellin et al. (46). solar grains provide direct constraint on and Ni and others rich in Ti and V.

Zinner et al. PNAS | November 29, 2011 | vol. 108 | no. 48 | 19137 creates a site-specific electron transparent by raster scanning. This method has been chromated X-ray source. Soft X-rays are membrane. The membrane is then ex- successfully applied to determine the also less damaging to many materials, par- tracted from the sample and attached to a location and composition of cometary ticularly organics, than high-energy elec- TEM support grid by in situ or ex situ fragments along dust particle tracks in trons. Hard X-ray XANES can be used to micromanipulation for subsequent TEM, Stardust aerogel (72, 73). These studies characterize thicker samples with ∼1 eV SIMS, or XANES analysis. Needle-shaped found compositional differences between energy resolution, including submicron specimens for atom probe tomography can the debris along tracks and terminal par- particles captured in aerogel (85). How- also be produced. ticles. Cluster IDPs, analyzed in a similar ever, the achievable spatial resolution of way, might be an analog to cometary par- ELNES (subnanometer) is much greater Atom Probe Tomography ticles collected by Stardust (74). An im- than that of XANES (>10 nm), and 0.1 Atom probe tomography is a time of flight pressive SXRF study is the measurement eV energy resolution can be achieved in MS method for atom by atom tomographic of trace element abundances in individual a monochromated electron reconstruction of needle-shaped specimens presolar SiC grains ∼2 μm in size, pro- (60, 88). (66). Atoms are evaporated from the viding evidence that the short-lived iso- needle tip by a combination of applied tope 93Zr had condensed into the grains at Raman Microprobe high-voltage and pulsed laser heating and the time of their formation (75). gives information on are collected with a 2D position sensitive molecular bonds, and the Raman micro- detector. Using an estimate of the radius XRCMT. The 3D internal structure of an probe allows analysis on a submicrometer of curvature of the needle tip (50–150 nm) object can be obtained by combining many level. It has been successfully applied to and the TOF and position of a detected X-ray images, usually by rotating the the study of insoluble organic matter in atom, the mass and the original location sample (71, 76). Images of X-ray attenu- primitive meteorites (89), where it was of the atom in the specimen can be de- ation yield 3D density structure. This found that metamorphic processes and termined. Recent atom probe measure- technique has been applied to determine radiation affect the Raman signal to the ments of SiC grains show promise for the location and size of cometary particle identification of ultra-primitive IDPs (23) characterization of trace element segre- fragments in Stardust aerogel tracks (77, (see above), the analysis of returned gation in presolar grains that could result 78). X-ray tomography can also be done Stardust samples (90), and presolar SiC from heterogeneous nucleation or ion from XRF images and thus, provides the grains (91). In the last study, the Raman implantation of circumstellar or inter- 3D distribution of different elements. of a supernova grains indicates stellar gas (67, 68). Preparation of samples However, this analysis requires a pencil crystallographic disorder, whereas grains that evaporate uniformly is the major beam and is much more time intensive. from AGB stars have a well-crystallized challenge in all atom probe . cubic structure. Needles of pure metal specimens can Synchrotron Spec- be obtained by electrochemical etching, troscopy. The use of infrared light from NMR Spectroscopy but most samples are now prepared by synchrotron light sources leads to an in- Meteorites and IDPs contain organic ma- FIB techniques. crease in brightness of 100–1,000 times over terial, some of which might have a presolar conventional IR sources and allows imag- origin. Recently, NMR analysis has been Analysis with Synchrotron Radiation ing with diffraction-limited beam spots. The used to determine the structure of organic The installation of third-generation elec- achieved high sensitivity is instrumental macromolecules, the insoluble organic tron storage rings specifically designed for for the analysis of small samples such as matter (IOM). In -state NMR spec- the production of synchrotron radiation volatile cometary material deposited in troscopy, the resonant of a resulted in new capabilities for micro- aerogel tracks from the Stardust mission, one-half nucleus such as 1H or 13C de- analysis. In these facilities, high-intensity allowing for the identification of several pends on its electronic environment. Thus, X-rays are produced by insertion devices organic compounds such as amines and an NMR spectrum provides information (wigglers and undulators) in the path of amino acids (79, 80). about the bonding of these nuclei (92). the electron beam and after selection of The study of IOM from primitive meteor- a small energy range by a monochromator, XANES. SynchrotronXANES(81)andTEM- ites revealed many aromatic and aliphatic can be focused down to diameters of <1 based electron loss near-edge spectros- functional groups as well as diamond (92, μm by microfocusing mirrors (69). This copy (ELNES) (82) probe the energy- 93). It was found that the relative abun- makes the high-sensitivity analysis of small level structure of atoms in a material. In dances of aromatic and aliphatic as samples possible. There are several ana- XANES, the absorption of a monochro- well as nanodiamonds vary with meteorite lytical techniques making use of synchro- mated, synchrotron X-ray source because group and might provide information on tron radiation (70) that have been applied of excitation of electrons from an inner the oxidative of aqueous fluids on to extraterrestrial samples. Among the shell is measured as a function of energy. the meteorites’ parent bodies. techniques are XRF, X-ray computed mi- In ELNES, a type of TEM-EELS, the in- crotomography (XRCMT), X-ray diffrac- tensity of of the incident ICP-MS tion (XRD), X-ray absorption fine electron beam by the sample because of The mid-1990s saw the development of structure (XAFS), and XANES. core-level excitation is measured as a func- ICP-MS equipped with multiple collectors tion of the energy loss. Both techniques (MC-ICP-MS). ICP sources can ionize XRF Analysis. In synchrotron XRF analysis, are commonly used in cosmochemistry to most elements and have permitted the the (usually monochromatic) finely focused determine oxidation states of Fe (83–85), precise isotopic measurement of elements, X-rays are used to produce characteristic Ti (25, 86), and other transition metals and such as transition metals W, Hf, and Zr, X-rays from the sample, which are analyzed to fingerprint carbon bond distributions which are poorly ionized by the state of for their energy, giving information on (87) (e.g., graphite vs. diamond vs. different the art TIMS. Because of rapid sample the elemental composition of the sample organic molecules) to constrain formation throughput and because the instrumental (71). Because of the atomic charge (Z) conditions. In general, soft X-ray XANES mass bias varies smoothly during an ana- dependence of fluorescence, XRF is es- has greater sensitivity and energy resolu- lytical session, the correction of the in- pecially suited to the analysis of heavier tion (<0.1 eV) than does most ELNES strumental mass bias can be made with elements. Element images can be obtained (1 eV) because of the bright mono- an element different from the one being

19138 | www.pnas.org/cgi/doi/10.1073/pnas.1015118108 Zinner et al. analyzed (e.g., Cu for Zn) and by brack- the absence of 58Fe-isotopic anomalies derived from the W/U ratio of lunar rocks eting standards (94). The combination of larger than 0.3–0.5 ε in bulk meteorites (114), implies a time for the giant im- laser ablation with MC-ISP-MS has per- argues for the injection of 60Fe in the early pact >60 Myr after SS formation. How- mitted precise in situ measurements of SS and its homogenization before the ever, Yin et al. and Yin and Antognini Mg- and Si-isotopic ratios (95, 96). formation of planetary bodies (100). (115, 116) argued that the Hf/W ratios During the last 15 y, MC-ICP-MS has of the two planetary bodies were simi- become one of the most important tech- Tungsten Isotopes: Age of the Metal/Silicate lar, reducing the time to ∼30 Myr, as niques in and cos- Differentiation on Earth and Asteroids and initially suggested (106, 107). mochemistry laboratories. Here, we focus the Giant Impact as the Origin of the Moon. on high-precision MC-ICP-MS isotopic Although W is a moderately siderophile Variations of Stable Isotopes of Heavy Ele- analyses that have led to breakthrough element, Hf is a lithophile element and is ments: Tracers of SS Processes. Small stable discoveries in cosmochemistry. strongly fractionated from W during core 182 182 isotopic fractionations of heavy elements formation. Hf/ W chronometry can have been measured by MC-ICP-MS in Isotopic Heterogeneity in the Solar Nebula. date Hf/W fractionations that occurred up 182 meteorites and lunar samples for moder- The presence of presolar grains in primi- to ∼60 Myr after the formation of Hf ately volatile elements (e.g., Zn and Cd) tive meteorites is evidence for incom- (half- = 9 Myr). Comparison of ter- (117, 118) and more refractory elements plete homogenization of presolar material restrial mantle samples with chondrites (e.g., Fe and Ni) (119, 120). These isotopic during SS formation. Although presolar has been used to evaluate the timing of variations, which are too small to be mea- grain can be analyzed individually, recent terrestrial core formation (104–107). Al- sured by any other instrument, brought improvements in analytical methods and though Lee and Halliday (105) did not additional constraints on the volatile his- instrumentation, notably MC-ICP-MS, find any difference in the W-isotopic tory and the physical processes (e.g., have permitted resolution of small isotopic composition between terrestrial samples fi heterogeneities for several elements in and chondrites, later studies detected impacts), which have modi ed the mete- bulk meteorites (e.g., Ti and Ni) (97–99), a small but resolvable ∼20 ppm excess of orite parent bodies and the Earth. The whereas Fe and Zn have uniform isotopic 182W in the Earth relative to chondrites abundance of Zn, a moderately volatile compositions (100, 101). Measuring the (106–108). These results imply that core element, in carbonaceous chondrites de- abundance of several isotopes produced mantle differentiation occurred probably creases in this order: CI > CM > CV-CO by the same process provides useful con- within 30 Myr after SS formation. > Earth (121). Its isotopic composition straints on the nucleosynthetic processes Iron meteorites, thought to represent the decreases in the same order from iso- responsible for the isotopic anomalies. In core of asteroids, have deficits of 3–5 ε in topically heaviest in CIs to isotopically addition, correlated isotopic effects are 182W/184W ratio compared with terrestrial lightest in the Earth (117). The opposite used to quantify homogeneity in the SS samples (109–112). These deficits corre- pattern is expected if the Zn depletion in distribution of extinct radionuclides (e.g., spond to differentiation ages of ∼1–5 Zn in chondrites and Earth relative to 60 fi Fe T1/2 = 1.5 Myr) that could possibly be Myr after SS formation. The rst Pb-Pb CI chondrites is because of volatilization. used as chronometers. For instance, 58Fe dating of Group IVA iron meteorites The observed pattern is an argument in and 60Fe are synthesized together in core confirmed this rapid differentiation of favor of an incomplete origin for collapse supernovae or AGB stars by iron meteorite parent bodies (113). the volatile depletion in the SS (122). neutron capture reactions (102). Corre- The silicate fraction of the Moon has 50 54 62 182 184 lated isotopic anomalies of Ti, Cr, Ni, the same W/ W ratio as the Earth’s ACKNOWLEDGMENTS. We thank Steve Sutton for and 64Ni (97–99, 103) have been observed mantle (114). The implications of this re- providing information on synchrotron radiation analysis. This work was supported by National in meteorites and suggest some large-scale sult on the time of the giant impact as the Aeronautics and Space Administration Funds isotopic heterogeneity that has survived origin of the Moon depend on its Hf/W NNX08AG71G (to E.K.Z.), NNX09AM64G (to F.M.), mixing within the solar nebula. However, ratio. A higher than terrestrial Hf/W ratio, and NNH09AL20I (to R.M.S.).

1. Maurette M (2006) Micrometeorites and the Mysteries 12. Zinner E (1989) Isotopic measurements with the ion nucleosynthesis, , and dust formation. of our Origins (Springer, Heidelberg). microprobe. New Frontiers in Stable Isotope Research: Astrophys J 719:1370–1384. 2. Brownlee DE (1985) : Collection and Laser Probes, Ion Probes, and Small-Sample Analysis, 21. Busemann H, et al. (2006) Interstellar chemistry research. Annu Rev Earth Planet Sci 13:147–173. eds Shanks WC, III, Criss RE (US Geological Survey), US recorded in organic matter from primitive meteorites. 3. Bradley JP (2004) Interplanetary dust particles. Geological Survey Bulletin 1890, pp 145–162. Science 312:727–730. Meteorites, Planets, and Comets: Treatise on 13. Ireland TR (2003) SIMS measurement of stable 22. Floss C, et al. (2006) Identification of isotopically Geochemistry, eds Holland HD, Turekian KK (Elsevier- isotopes. Handbook of Stable Isotope Analytical primitive interplanetary dust particles: A NanoSIMS Pergamon, Oxford), Vol 1, pp 689–711. Techniques,eddeGrootPA,pp652–691. isotopic imaging study. Geochim Cosmochim Acta 70: 4. Brownlee D, et al. (2006) Comet 81P/Wild 2 under 14. Clayton DD, Nittler LR (2004) with 2371–2399. a microscope. Science 314:1711–1716. presolar stardust. Annu Rev Astron Astrophys 42: 23. Busemann H, et al. (2009) Ultra-primitive interplanetary 5. Yano H, et al. (2006) Touchdown of the Hayabusa 39–78. spacecraft at the Muses Sea on Itokawa. Science 312: 15. Zinner E (2007) Presolar grains. Treatise on Geochemistry dust particles from the comet 26P/Grigg-Skjellerup dust 1350–1353. Update, eds Holland HD, Turekian KK, Davis A (Elsevier stream collection. Earth Planet Sci Lett 288:44–57. 6. Burnett DS, et al. (2003) The Genesis discovery Ltd, Oxford), Vol 1.02, pp 1–33. 24. Stadermann FJ, et al. (2008) Stardust in Stardust—the mission: Return of solar matter to earth. Space Sci Rev 16. Hillion F, Horreard F, Stadermann FJ (2000) Recent C, N, and O isotopic compositions of Wild 2 cometary 105:509–534. results and developments on the CAMECA NanoSIMS matter in Al foil impacts. Meteorit Planet Sci 43: 7. Clayton RN, Grossman L, Mayeda TK (1973) A 50. Proceedings of the 12th International Conference 299–313. component of primitive nuclear composition in onSecondary Ion Mass Spectrometry (John Wiley & Sons, 25. Messenger S, et al. (2009) Discovery of presolar SiC carbonaceous meteorites. Science 182:485–488. Brussels), pp 209–212. from Comet WILD-2. Lunar Planet Sci 40:1790. 8. Lee T, Panastassiou DA, Wasserburg GJ (1976) Demon- 17. Messenger S, Keller LP, Stadermann FJ, Walker RM, 26. Simon SB, et al. (2008) A refractory inclusion returned 26 stration of Mg excess in Allende and evidence for Zinner E (2003) Samples of stars beyond the solar by Stardust from comet 81P/Wild 2. Meteorit Planet 26Al. Geophys Res Lett 3:109–112. system: Silicate grains in interplanetary dust. Science Sci 43:1861–1877. 9. Wasserburg GJ (1987) Isotopic abundances: Inferences 300:105–108. 27. Nakamura T, et al. (2008) Chondrulelike objects in on solar system and planetary evolution. Earth Planet 18. Nguyen AN, Zinner E (2004) Discovery of ancient silicate short-period comet 81P/Wild 2. Science 321:1664–1667. Sci Lett 86:129–173. stardust in a meteorite. Science 303:1496–1499. 28. Villeneuve J, Chaussidon M, Libourel G (2009) 10. Westphal AJ, et al. (2004) Aerogel keystones: Extraction 19. Nittler LR, et al. (1995) Silicon nitride from 26 of complete hypervelocity impact events from aerogel supernovae. Astrophys J 453:L25–L28. Homogeneous distribution of Al in the solar system collectors. Meteorit Planet Sci 39:1375–1386. 20. Hoppe P, et al. (2010) NanoSIMS studies of small from the Mg isotopic composition of chondrules. 11. (2008) Meteorit Planet Sci 43(1–2). presolar SiC grains: New insights into supernova Science 325:985–988.

Zinner et al. PNAS | November 29, 2011 | vol. 108 | no. 48 | 19139 29. MacPherson GJ, et al. (2010) Early solar nebula 55. Bernatowicz TJ, et al. (1996) Constraints on stellar 79. Sandford SA, et al. (2006) Organics captured from condensates with canonical, not supracanonical, grain formation from presolar graphite in the comet 81P/Wild 2 by the Stardust spacecraft. Science initial 26Al/27Al ratios. Astrophys J 711:L117–L121. . Astrophys J 472:760–782. 314:1720–1724. 30. Nagashima K, Krot AN, Yurimoto H (2004) Stardust 56. Stroud RM, Nittler LR, Alexander CMOD (2004) 80. Bajt S, et al. (2009) of Wild 2 silicates from primitive meteorites. Nature 428: Polymorphism in presolar Al2O3 grains from asymptotic particle hypervelocity tracks in Stardust aerogel: 921–924. giant branch stars. Science 305:1455–1457. Evidence for the presence of volatile organics in 31. Sakamoto N, et al. (2007) Remnants of the early solar 57. Vollmer C, et al. (2009) Direct laboratory analysis of cometary dust. Meteorit Planet Sci 44:471–484. system enriched in heavy oxygen isotopes. silicate stardust from red giant stars. Astrophys J 700: 81. Koningsberger DC, Prins R (1988) X-Ray Absorption: Science 317:231–233. 774–782. Principles, Applications, Techniques of EXAFS, 32. Mao PH, et al. (2005) Preliminary evaluation of the 58. Messenger S, Keller LP, Lauretta DS (2005) Supernova SEXAFS, and XANES (Wiley, New York). secondary ion/accelerator mass spectromer, MegaSIMS. olivine from cometary dust. Science 309:737–741. 82. Egerton RF (1996) Electron Energy-Loss Spectroscopy Lunar Planet Sci 36:2259. 59. Ishii HA, et al. (2008) Comparison of comet 81P/Wild 2 in the Electron Microscope (Plenum, New York). 33. Mao PH, et al. (2006) MegaSIMS update: Oxygen dust with interplanetary dust from comets. Science 83. Zega TJ, Garvie LAJ, Buseck PR (2003) Nanometer-scale – transmission, destruction of OH molecular ions, and 319:447 450. measurements of iron oxidation states of cronstedtite stability of three-isotope measurements. Lunar Planet 60. Bradley JP, Dai ZR (2009) Analytical SuperSTEM for from primitive meteorites. Am Miner 88:1169–1172. extraterrestrial materials research. Meteorit Planet Sci 37:2153. 84. Ogliore RC, et al. (2010) Comparison of the oxidation Sci 44:1627–1642. 34. Kallio APA, et al. (2010) isotopic state of Fe in comet 81P/Wild 2 and chondritic-porous 61. Krivanek OL, et al. (2010) Atom-by-atom structural composition of solar wind returned by the Genesis interplanetary dust particles. Earth Planet Sci Lett 296: and chemical analysis by annular dark-field electron mission. Lunar Planet Sci 41:2481. 278–286. microscopy. Nature 464:571–574. 35. McKeegan KD, et al. (2010) Genesis SiC concentrator 85. Westphal AJ, et al. (2009) Mixing fraction of inner 62. Zega TJ, et al. (2007) Coordinated isotopic and sample traverse: Confirmation of 16O-depletion of solar system material in comet 81P/Wild 2. Astrophys J mineralogic analyses of planetary materials enabled terrestrial oxygen. Lunar Planet Sci 41:2589. 694:18–28. by in situ lift-out with a focused ion beam scanning 36. Owen T, et al. (2001) Protosolar nitrogen. Astrophys J 86. Chi M, et al. (2009) The origin of refractory minerals in electron microscope. Meteorit Planet Sci 42: 553:L77–L79. comet 81P/Wild 2. Geochim Cosmochim Acta 73: 1373–1386. 37. Wiens RC, Huss GR, Burnett DS (1999) The solar oxygen- 7150–7161. 63. Graham GA, et al. (2008) Applied focused ion beam isotopic composition: Predictions and implications for 87. Cody GD, et al. (2008) Quantitative organic and light- techniques for of astromaterials solar nebula processes. Meteorit Planet Sci 34:99–107. element analysis of comet 81P/Wild 2 particles using C-, for integrated nanoanalysis. Meteorit Planet Sci 43: N-, and O-mu-XANES. Meteorit Planet Sci 43:353–365. 38. Marty B, et al. (2010) Nitrogen isotopes in the recent – 561 569. 88. Krivanek OL, et al. (2009) High-energy-resolution solar wind from the analysis of Genesis targets: 64. Leroux H, et al. (2008) Transmission electron Evidence for large scale isotope heterogeneity in the monochromator for aberration-corrected scanning microscopy of cometary residues from micron-sized transmission electron microscopy/electron energy-loss early solar system. Geochim Cosmochim Acta 74: craters in the Stardust Al foils. Meteorit Planet Sci 43: spectroscopy. Philos Transact A Math Phys Eng Sci 340–355. 143–160. 367:3683–3697. 39. Meshik A, et al. (2007) Constraints on neon and 65. Giannuzzi LA, Stevie FA (2005) Introduction to Focused 89. Busemann H, Alexander CMOD, Nittler LR (2007) isotopic fractionation in solar wind. Science 318: Ion Beams: Instrumentation, Theory, Techniques, and Characterization of insoluble organic matter in 433–435. Practice (Springer, New York). primitive meteorites by microRaman spectroscopy. 40. Marty B, et al. (2008) Helium and neon abundances 66. Kelly TF, Miller MK (2007) Invited review article: Atom Meteorit Planet Sci 37:1387–1416. and compositions in cometary matter. Science 319: probe tomography. Rev Sci Instrum 78:031101–031129. 90. Rotundi A, et al. (2008) Combined micro-Raman, 75–78. 67. Heck PR, et al. (2010) Atom-probe tomographic micro-infrared, and field emission scanning electron 41. Floss C, et al. (2010) A NanoSIMS and Auger analyses of presolar grains and microscope analyses of comet 81P/Wild 2 particles Nanoprobe investigation of an isotopically primitive meteoritic nanodiamonds—first results on silicon collected by Stardust. Meteorit Planet Sci 43:367–397. interplanetary dust particle from the 55P/Tempel- carbide. Lunar Planet Sci 41:2112. 91. Wopenka B, et al. (2010) Raman and isotopic studies Tuttle targeted stratospheric dust collector. Meteorit 68. Stadermann FJ, et al. (2010) Atom-probe tomographic of large presolar SiC grains. Lunar Planet Sci 41:1390. Planet Sci 45:1889–1905. study of the three-dimensional structure of presolar 92. Cody GD, Alexander CMOD, Tera F (2002) Solid-state 42. Stadermann FJ, et al. (2009) The use of Auger silicon carbide and nanodiamonds at atomic (1Hand13C) nuclear magnetic resonance spectroscopy spectroscopy for the in situ elemental characterization resolution. Lunar Planet Sci 41:2134. of insoluble organic residue in the Murchison of sub-micrometer presolar grains. Meteorit Planet Sci 69. Sham TK, Rivers ML (2002) A brief overview of meteorite: A self-consistent quantititive analysis. 44:1033–1049. synchrotron radiation. Rev Miner Geochem 49: Geochim Cosmochim Acta 66:1851–1865. 43. Savina MR, et al. (2003) Analyzing individual presolar 118–147. 93. Cody GD, Alexander CMOD (2005) NMR studies of grains with CHARISMA. Geochim Cosmochim Acta 67: 70. Brown J, G E, Sturchio NC (2002) An overview of chemical structural variation of insoluble organic 3215–3225. synchrotron radiation applications to low temperature matter from different 44. Levine J, et al. (2009) Resonance ionization mass geochemistry and environmental science. Rev Miner groups. Geochim Cosmochim Acta 69:1085–1097. spectrometry for precise measurements of isotope Geochem 49:1–115. fl 94. Albarède F, et al. (2004) Precise and accurate isotopic – 71. Sutton SR, et al. (2002) Micro uorescence and ratios. Int J Mass 288:36 43. measurements using multiple-collector ICPMS. 45. Lugaro M, et al. (2003) Isotopic compositions of microtomography analyses of heterogeneous earth Geochim Cosmochim Acta 68:2725–2744. strontium, zirconium, molybdenum, and barium in and environmental materials. Rev Miner Geochem 49: – 95. Shahar A, Young ED (2007) Astrophysics of CAI single presolar SiC grains and asymptotic giant branch 429 483. 72. Lanzirotti A, et al. (2008) Chemical composition and formation as revealed by silicon isotope LA-MC-ICPMS stars. Astrophys J 593:486–508. heterogeneity of Wild 2 cometary particles determined of an igneous CAI. Earth Planet Sci Lett 257:497–510. 46. Pellin MJ, et al. (1999) Molybdenum isotopic 26 27 by synchrotron x-ray fluorescence. Meteorit Planet Sci 96. Young ED, et al. (2005) Supra-canonical Al/ Al and composition of single silicon carbide grains from 43:187–214. the residence time of CAIs in the solar protoplanetary supernovae. Lunar Planet Sci 30:1969. 73. Ishii HA, et al. (2008) Recovering the elemental disk. Science 308:223–227. 47. Savina MR, et al. (2004) Extinct technetium in presolar composition of comet Wild 2 dust in five Stardust 97. Leya I, et al. (2008) Titanium isotopes and the radial silicon carbide grains. Science 303:649–652. impact tracks and terminal particles in aerogel. heterogeneity of the solar system. Earth Planet Sci 48. Merrill PW (1952) Spectroscopic observations of stars Meteorit Planet Sci 43:215–231. Lett 266:233–244. of class S. Astrophys J 116:21–26. 74. Flynn GJ, Lanzirotti A, Sutton SR (2009) Elemental and 98. Trinquier A, et al. (2009) Origin of nucleosynthetic 49. Burbidge EM, et al. (1957) Synthesis of the elements mineralogical compositions of cluster IDPs: A possible isotope heterogeneity in the solar protoplanetary in stars. Rev Mod Phys 29:547–650. analog of the Wild 2 particles collected by Stardust. disk. Science 324:374–376. 50. Clemett SJ, Maechling CR, Zare RN, Swan PD, Lunar Planet Sci 40:1166. 99. Regelous M, Elliott T, Coath CD (2008) Nickel isotope Walker RM (1993) Identification of complex aromatic 93 75. Kashiv Y, et al. (2010) Extinct Zr in single presolar heterogeneity in the early Solar System. Earth Planet molecules in individual interplanetary dust particles. SiC grains from low mass asymptotic giant branch Sci Lett 272:330–338. – Science 262:721 725. stars and condensation from Zr-depleted gas. 100. Dauphas N, et al. (2008) Iron 60 evidence for early 51. Messenger S, et al. (1998) Indigenous polycyclic Astrophys J 713:212–219. injection and efficient mixing of stellar debris in the aromatic hydrocarbons in circumstellar graphite 76. Ebel D, Rivers ML (2007) Meteorite 3-D synchrotron protosolar nebula. Astrophys J 686:560–569. grains from primitive meteorites. Astrophys J 502: microtomography: Methods and applications. Meteorit 101. Moynier F, Dauphas N, Podosek FA (2009) A Search 284–295. Planet Sci 42:1627–1646. for 70Zn Anomalies in Meteorites. Astrophys J 700: 52. Clemett SJ, et al. (2010) Complex aromatic hydro- 77. Tsuchiyama A, et al. (2009) Three-dimensional L92–L95. in Stardust samples collected from comet structures and elemental distributions of Stardust 102. Clayton DD (2003) Handbook of Isotopes in the 81P/Wild 2. Meteorit Planet Sci 45:701–722. impact tracks using synchrotron microtomography Cosmos: to (Cambridge University 53. Knie K, et al. (2004) 60Fe anomaly in a deep-sea and X-ray fluorescence analysis. Meteorit Planet Sci Press, Cambridge, UK). manganese crust and implications for a nearby 44:1203–1224. 103. Steele RCJ, et al. (2010) Correlated neutron rich Ni supernova source. Phys Rev Lett 93:171103-1–171103-4. 78. Ebel DS, et al. (2009) Three-dimensional textural and isotope anomalies in chondritic and iron meteorites. 54. Williams DB, Carter CB (2008) Transmission Electron compositional analysis of particle tracks and Lunar Planet Sci 44:1984. Microscopy: A Textbook for fragmentation history in aerogel. Meteorit Planet Sci 104. Harper CL, Jr., Jacobsen SB (1996) Evidence for 182Hf (Springer, New York). 44:1445–1463. in the early Solar System and constraints on the

19140 | www.pnas.org/cgi/doi/10.1073/pnas.1015118108 Zinner et al. timescale of terrestrial accretion and core formation. 111. Schersten A, et al. (2006) Hf-W evidence for rapid 117. Luck JM, Othman DB, Albarede F (2005) Zn and Cu Geochim Cosmochim Acta 60:1131–1153. differentiation of iron meteorite parent bodies. Earth isotopic variations in chondrites and iron meteorites: 105. Lee DC, Halliday AN (1995) Hafnium-tungsten Planet Sci Lett 241:530–542. Early solar nebula reservoirs and parent-body pro- chronometry and the timing of terrestrial core 112. Qin L, et al. (2008) Rapid accretion and differentiation cesses. Geochim Cosmochim Acta 69:5351–5363. formation. Nature 378:771–774. of iron meteorite parent bodies inferred from 118. Wombacher F, et al. (2008) Cadmium stable isotope 106. Kleine T, Münker C, Mezger K, Palme H (2002) Rapid 182Hf-182Wchronometryandthermalmodeling.Earth cosmochemistry. Geochim Cosmochim Acta 72: accretion and early core formation on asteroids and Planet Sci Lett 273:94–104. 646–667. the terrestrial planets from Hf-W chronometry. 113. Blichert-Toft J, et al. (2010) The early formation of the 119. Poitrasson F, et al. (2004) Iron isotope differences Nature 418:952–955. IVA iron meteorite parent body. Earth Planet Sci Lett between Earth, Moon, Mars and Vesta as possible 107. Yin Q, et al. (2002) A short timescale for terrestrial 296:269–280. records of contrasted accretion mechanisms. Earth planet formation from Hf-W chronometry of 114. Touboul M, Kleine T, Bourdon B, Palme H, Wieler R Planet Sci Lett 223:253–266. meteorites. Nature 418:949–952. (2007) Late formation and prolonged differentiation 120. Moynier F, et al. (2007) Comparative stable isotope 108. Schoenberg R, et al. (2002) New W-isotope evidence of the Moon inferred from W isotopes in lunar geochemistry of Ni, Cu, Zn, and Fe in chondrites for rapid terrestrial accretion and very early core metals. Nature 450:1206–1209. and iron meteorites. Geochim Cosmochim Acta 71: formation. Geochim Cosmochim Acta 66:3151–3160. 115. Yin Q-Z, Tollstrup D, Wimpenny J (2010) Constraining 4365–4379. 109. Horan MF, Smoliar MI, Walker RJ (1998) 182W the timing of giant-impact and the origin of the Earth- 121. Lodders K, Fegley B, Jr. (1998) The Planetary Scientist’s and 187Re-187Os systematics of iron meteorites: Moon system. New advances in lunar exploration. Companion (Oxford University Press, London). Chronology for melting, differentiation, and crystal- Proceedings of the International Symposium on Lunar 122. Albarède F (2009) Volatile accretion history of the lization in asteroids. Geochim Cosmochim Acta 62: Science,edsOuyangZ,LpWH,TangZ(MacauUniversity terrestrial planets and dynamic implications. Nature 545–554. of Science and Technology, Macau), pp 71–91. 461:1227–1233. 110. Markowski A, et al. (2006) Tungsten isotopic composi- 116. Yin Q-Z, Antognini J (2008) Isotopic and elemental 123. Stroud RM, et al. (2003) Transmission electron tions of iron meteorites: Chronological constraints vs. constraints on the first 100 Myr of earth history. microscopy of non-etched presolar silicon carbide. cosmogenic effects. Earth Planet Sci Lett 242:1–15. Geochim Cosmochim Acta (Suppl 72):A1061. Lunar Planet Sci 34:1755.

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