P. Hoppe

Max Planck Institute for Chemistry, Mayence, Rheinland-Pfalz, Germany

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Publications (354)876.05 Total impact

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    ABSTRACT: We have performed in situ analyses of C and O isotopic compositions, trace element concentrations, and cathodoluminescence (CL) intensities on calcite in Murchison, a weakly altered CM chondrite. We found that the trace element (Mg, Mn, and Fe) concentrations are heterogeneous within single calcite grains. Grain to grain heterogeneity is even more pronounced. The analyzed calcite grains can be separated into two distinct types with respect to their C isotopic ratios, trace element concentrations, and CL characteristics: Calcite grains with higher δ13CPDB values (∼75 ‰) have low trace element concentrations and uniformly dark CL, while grains with lower δ13C values (∼35 ‰) have higher trace element concentrations and CL zoning. In contrast to the C isotopic ratios, O isotopic ratios are similar for both types of calcites (δ18OSMOW ∼ 34 ‰).
    Geochimica et Cosmochimica Acta 04/2015; 161. DOI:10.1016/j.gca.2015.04.010 · 4.25 Impact Factor
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    46th Lunar and Planetary Science Conference, Woodlands, TX; 03/2015
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    ABSTRACT: Isotopically anomalous carbonaceous grains in extraterrestrial samples represent the most pristine organics that were delivered to the early Earth. Here we report on gentle aberration-corrected scanning transmission electron microscopy investigations of eight (15)N-rich or D-rich organic grains within two carbonaceous Renazzo-type (CR) chondrites and two interplanetary dust particles (IDPs) originating from comets. Organic matter in the IDP samples is less aromatic than that in the CR chondrites, and its functional group chemistry is mainly characterized by C-O bonding and aliphatic C. Organic grains in CR chondrites are associated with carbonates and elemental Ca, which originate either from aqueous fluids or possibly an indigenous organic source. One distinct grain from the CR chondrite NWA 852 exhibits a rim structure only visible in chemical maps. The outer part is nanoglobular in shape, highly aromatic, and enriched in anomalous nitrogen. Functional group chemistry of the inner part is similar to spectra from IDP organic grains and less aromatic with nitrogen below the detection limit. The boundary between these two areas is very sharp. The direct association of both IDP-like organic matter with dominant C-O bonding environments and nanoglobular organics with dominant aromatic and C-N functionality within one unique grain provides for the first time to our knowledge strong evidence for organic synthesis in the early solar system activated by an anomalous nitrogen-containing parent body fluid.
    Proceedings of the National Academy of Sciences 10/2014; 111(43). DOI:10.1073/pnas.1408206111 · 9.81 Impact Factor
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    ABSTRACT: With the discovery of bona fide extraterrestrial materials in the Stardust Interstellar Dust Collector, NASA now has a fundamentally new returned sample collection, after the Apollo, Antarctic meteorite, Cosmic Dust, Genesis, Stardust Cometary, Hayabusa, and Exposed Space Hardware samples. Here, and in companion papers in this volume, we present the results from the Preliminary Examination of this collection, the Stardust Interstellar Preliminary Examination (ISPE). We found extraterrestrial materials in two tracks in aerogel whose trajectories and morphology are consistent with an origin in the interstellar dust stream, and in residues in four impacts in the aluminum foil collectors. While the preponderance of evidence, described in detail in companion papers in this volume, points toward an interstellar origin for some of these particles, alternative origins have not yet been eliminated, and definitive tests through isotopic analyses were not allowed under the terms of the ISPE. In this summary, we answer the central questions of the ISPE: How many tracks in the collector are consistent in their morphology and trajectory with interstellar particles? How many of these potential tracks are consistent with real interstellar particles, based on chemical analysis? Conversely, what fraction of candidates are consistent with either a secondary or interplanetary origin? What is the mass distribution of these particles, and what is their state? Are they particulate or diffuse? Is there any crystalline material? How many detectable impact craters (>100 nm) are there in the foils, and what is their size distribution? How many of these craters have analyzable residue that is consistent with extraterrestrial material? And finally, can craters from secondaries be recognized through crater morphology (e.g., ellipticity)?
    Meteoritics & planetary science 09/2014; 49(9):1720. DOI:10.1111/maps.12221 · 2.83 Impact Factor
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    ABSTRACT: We report O and Mg isotope compositions of presolar silicate grains which likely formed around asymptotic giant branch stars. Our grains represent the most abundant Mg-rich presolar grain group and their Mg isotope composition provides thus far missing information about the contribution of isotopically anomalous presolar dust to the Mg isotope inventory of the early Solar System. Presolar silicate grains were identified in situ, using the NanoSIMS, in the matrix of the ungrouped carbonaceous chondrite Acfer 094. O isotope compositions suggest that the presolar grains of the present study formed in the stellar winds of low mass (M ⩽ ∼2.2 × Msolar) red giant or asymptotic giant branch stars of close-to-solar metallicity and thus belong to the most abundant presolar silicate grain group. In order to minimise matrix contributions during spatially poorly resolved Mg isotope analyses (spatial resolution comparable to average grain size), meteorite matrix in the presolar grains’ vicinity was removed using a focussed Ga ion beam. To monitor accuracy, we prepared and analysed O-isotopically regular (Solar System) matrix grains the same way as the presolar grains. The 25Mg/24Mg ratios of all seven successfully analysed presolar silicate grains are identical to that of the Solar System at the precision of our measurements. The 26Mg/24Mg ratios of five grains are also solar but two grains have significant positive anomalies in 26Mg/24Mg. On average, however, 25Mg/24Mg and 26Mg/24Mg ratios are higher than solar by a few %. All grain compositions are consistent with Galactic chemical evolution and, possibly, isotope fractionation caused by interstellar or Solar System processing (sputtering and/or recondensation). The grain with the strongest enrichment in 26Mg relative to 25Mg (δ25Mg = 34 ± 25‰, δ26Mg = 127 ± 25‰; where δxMg = 1000 × [(xMg/24Mg)grain/(xMg/24Mg)meteorite matrix) − 1] with x = 25 or 26; the reported uncertainty corresponds to 1 σ), probably incorporated 26Al during grain condensation. Our and previously reported Mg isotope data on presolar oxide and silicate grains indicate that the isotopically anomalous O-rich dust component of the Solar System’s parent molecular cloud was heterogeneous with respect to Mg isotope compositions and probably had a higher 26Mg/24Mg ratio on average than that of the present-day Solar System.
    Geochimica et Cosmochimica Acta 09/2014; 140:577–605. DOI:10.1016/j.gca.2014.05.053 · 4.25 Impact Factor
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    ABSTRACT: Abstract–Hard X-ray, quantitative, fluorescence elemental imaging was performed on the ID22NI nanoprobe and ID22 microprobe beam lines of the European Synchrotron Research facility (ESRF) in Grenoble, France, on eight interstellar candidate impact features in the framework of the NASA Stardust Interstellar Preliminary Examination (ISPE). Three features were unambiguous tracks, and the other five were identified as possible, but not definite, impact features. Overall, we produced an absolute quantification of elemental abundances in the 15 ≤ Z ≤ 30 range by means of corrections of the beam parameters, reference materials, and fundamental atomic parameters. Seven features were ruled out as interstellar dust candidates (ISDC) based on compositional arguments. One of the three tracks, I1043,1,30,0,0, contained, at the time of our analysis, two physically separated, micrometer-sized terminal particles, the most promising ISDCs, Orion and Sirius. We found that the Sirius particle was a fairly homogenous Ni-bearing particle and contained about 33 fg of distributed high-Z elements (Z > 12). Orion was a highly heterogeneous Fe-bearing particle and contained about 59 fg of heavy elements located in hundred nanometer phases, forming an irregular mantle that surrounded a low-Z core. X-ray diffraction (XRD) measurements revealed Sirius to be amorphous, whereas Orion contained partially crystalline material (Gainsforth et al. 2014). Within the mantle, one grain was relatively Fe-Ni-Mn-rich; other zones were relatively Mn-Cr-Ti-rich and may correspond to different spinel populations. For absolute quantification purposes, Orion was assigned to a mineralogical assemblage of forsterite, spinel, and an unknown Fe-bearing phase, while Sirius was most likely composed of an amorphous Mg-bearing material with minor Ni and Fe. Owing to its nearly chondritic abundances of the nonvolatile elements Ca, Ti, Co, and Ni with respect to Fe, in combination with the presence of olivine and spinel as inferred from XRD measurements, Orion had a high probability of being extraterrestrial in origin.
    Meteoritics & planetary science 09/2014; 49(9):1612. DOI:10.1111/maps.12208 · 2.83 Impact Factor
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    ABSTRACT: Here, we report the identification of 69 tracks in approximately 250 cm2 of aerogel collectors of the Stardust Interstellar Dust Collector. We identified these tracks through Stardust@home, a distributed internet-based virtual microscope and search engine, in which > 30,000 amateur scientists collectively performed >9 9 107 searches on approximately 106 fields of view. Using calibration images, we measured individual detection efficiency, and found that the individual detection efficiency for tracks > 2.5 lm in diameter was >0.6, and was >0.75 for tracks >3 lm in diameter. Because most fields of view were searched >30 times, these results could be combined to yield a theoretical detection efficiency near unity. The initial expectation was that interstellar dust would be captured at very high speed. The actual tracks discovered in the Stardust collector, however, were due to low-speed impacts, and were morphologically strongly distinct from the calibration images. As a result, the detection efficiency of these tracks was lower than detection efficiency of calibrations presented in training, testing, and ongoing calibration. Nevertheless, as calibration images based on low-speed impacts were added later in the project, detection efficiencies for lowspeed tracks rose dramatically. We conclude that a massively distributed, calibrated search, with amateur collaborators, is an effective approach to the challenging problem of identification of tracks of hypervelocity projectiles captured in aerogel.
    Meteoritics & planetary science 09/2014; 49(9):1509. DOI:10.1111/maps.12168 · 2.83 Impact Factor
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    ABSTRACT: The NASA Stardust mission used silica aerogel slabs to slowly decelerate and capture impinging cosmic dust particles for return to Earth. During this process, impact tracks are generated along the trajectory of the particle into the aerogel. It is believed that the morphology and dimensions of these tracks, together with the state of captured grains at track termini, may be linked to the size, velocity, and density of the impacting cosmic dust grain. Here, we present the results of laboratory hypervelocity impact experiments, during which cosmic dust analog particles (diameters of between 0.2 and 0.4 μm), composed of olivine, orthopyroxene, or an organic polymer, were accelerated onto Stardust flight-spare low-density (approximately 0.01 g cm−3) silica aerogel. The impact velocities (3–21 km s−1) were chosen to simulate the range of velocities expected during Stardust's interstellar dust (ISD) collection phases. Track lengths and widths, together with the success of particle capture, are analyzed as functions of impact velocity and particle composition, density, and size. Captured terminal particles from low-density organic projectiles become undetectable at lower velocities than those from similarly sized, denser mineral particles, which are still detectable (although substantially altered by the impact process) at 15 km s−1. The survival of these terminal particles, together with the track dimensions obtained during low impact speed capture of small grains in the laboratory, indicates that two of the three best Stardust candidate extraterrestrial grains were actually captured at speeds much lower than predicted. Track length and diameters are, in general, more sensitive to impact velocities than previously expected, which makes tracks of particles with diameters of 0.4 μm and below hard to identify at low capture speeds (<10 km s−1). Therefore, although captured intact, the majority of the interstellar dust grains returned to Earth by Stardust remain to be found.
    Meteoritics & planetary science 09/2014; 49(9):1666-1679. DOI:10.1111/maps.12173 · 2.83 Impact Factor
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    ABSTRACT: Seven particles captured by the Stardust Interstellar Dust Collector and returned to Earth for laboratory analysis have features consistent with an origin in the contemporary interstellar dust stream. More than 50 spacecraft debris particles were also identified. The interstellar dust candidates are readily distinguished from debris impacts on the basis of elemental composition and/or impact trajectory. The seven candidate interstellar particles are diverse in elemental composition, crystal structure, and size. The presence of crystalline grains and multiple iron-bearing phases, including sulfide, in some particles indicates that individual interstellar particles diverge from any one representative model of interstellar dust inferred from astronomical observations and theory.
    Science 08/2014; 345(6198):786. DOI:10.1126/science.1252496 · 31.48 Impact Factor
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    ABSTRACT: It has been suggested that the matrices of all chondrites are dominated by a common material with Ivuna-like (CI) abundances of volatiles, presolar grains and insoluble organic matter (IOM) (e.g., Alexander, 2005). However, matrix-normalized abundances of presolar silicon carbide (SiC) grains estimated from their noble gas components show significant variations in even the most primitive chondrites ( and ), in contradiction to there being a common chondrite matrix material. Here we report presolar SiC abundances determined by NanoSIMS raster ion imaging of IOM extracted from primitive members of different meteorite groups. We show that presolar SiC abundance determinations are comparable between NanoSIMS instruments located at three different institutes, between residues prepared by different demineralization techniques, and between microtomed and non-microtomed samples. Our derived SiC abundances in CR chondrites are comparable to those found in the CI chondrites (∼30 ppm) and are much higher than previously determined by noble gas analyses. The revised higher CR SiC abundances are consistent with the CRs being amongst the most primitive chondrites in terms of the isotopic compositions and disordered nature of their organic matter. Similar abundances between CR1, CR2, and CR3 chondrites indicate aqueous alteration on the CR chondrite parent body has not progressively destroyed SiC grains in them. A low SiC abundance for the reduced CV3 RBT 04133 can be explained by parent body thermal metamorphism at an estimated temperature of ∼440 °C. Minor differences between primitive members of other meteorite classes, which did not experience such high temperatures, may be explained by prolonged oxidation at lower temperatures under which SiC grains formed outer layers of SiO2 that were not thermodynamically stable, leading to progressive degassing/destruction of SiC.
    Geochimica et Cosmochimica Acta 08/2014; 139:248–266. DOI:10.1016/j.gca.2014.04.026 · 4.25 Impact Factor
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    ABSTRACT: Nutritional interactions between corals and symbiotic dinoflagellate algae lie at the heart of the structural foundation of coral reefs. Whilst the genetic diversity of Symbiodinium has attracted particular interest because of its contribution to the sensitivity of corals to environmental changes and bleaching (i.e. disruption of coral-dinoflagellate symbiosis), very little is known about the in hospite metabolic capabilities of different Symbiodinium types. Using a combination of stable isotopic labeling and nanoscale secondary ion mass spectrometry (NanoSIMS), we investigated the ability of the intact symbiosis between the reef-building coral Isopora palifera, and Symbiodinium C or D types, to assimilate dissolved inorganic carbon (via photosynthesis) and nitrogen (as ammonium). Our results indicate that Symbiodinium types from two clades naturally associated with I. palifera possess different metabolic capabilities. The Symbiodinium C type fixed and passed significantly more carbon and nitrogen to its coral host than the D type. This study provides further insights into the metabolic plasticity among different Symbiodinium types in hospite and strengthens the evidence that the more temperature tolerant Symbiodinium D type may be less metabolically beneficial for its coral host under non-stressful conditions.
    Environmental Microbiology 06/2014; DOI:10.1111/1462-2920.12518 · 6.24 Impact Factor
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    ABSTRACT: In-cloud production of sulfate modifies aerosol size distribution, with important implications for the magnitude of indirect and direct aerosol cooling and the impact of SO2 emissions on the environment. We investigate which sulfate sources dominate the in-cloud addition of sulfate to different particle classes as an air parcel passes through an orographic cloud. Sulfate aerosol, SO2 and H2SO4 were collected upwind, in-cloud and downwind of an orographic cloud for three cloud measurement events during the Hill Cap Cloud Thuringia campaign in autumn 2010 (HCCT-2010). Combined SEM and NanoSIMS analysis of single particles allowed the δ34S of particulate sulfate to be resolved for particle size and type. The most important in-cloud SO2 oxidation pathway at HCCT-2010 was aqueous oxidation catalysed by transition metal ions (TMI catalysis), which was shown with single particle isotope analyses to occur primarily in cloud droplets nucleated on coarse mineral dust. In contrast, direct uptake of H2SO4 (g) and ultrafine particulate were the most important sources modifying fine mineral dust, increasing its hygroscopicity and facilitating activation. Sulfate addition to "mixed" particles (secondary organic and inorganic aerosol) and coated soot was dominated by in-cloud aqueous SO2 oxidation by H2O2 and direct uptake of H2SO4 (g) and ultrafine particle sulfate, depending on particle size mode and time of day. These results provide new insight into in-cloud sulfate production mechanisms, and show the importance of single particle measurements and models to accurately assess the environmental effects of cloud processing.
    Atmospheric Chemistry and Physics 03/2014; 14(8). DOI:10.5194/acp-14-4219-2014 · 5.51 Impact Factor
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    ABSTRACT: We have determined the masses of seven Hayabusa grains, and the He,Ne content of three grains, all of which have a cosmic-ray exposure age of 1.5 Ma (within error).
  • J. Leitner, K. Metzler, P. Hoppe
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    ABSTRACT: Cluster chondrite clasts in two UOCs have higher presolar silicate abundances than previous studies suggested. One very large complex presolar grain was found.
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    ABSTRACT: Boron-10 excesses were found in asteroidal regolith, possibly due to implanted solar wind. However, the isotopic ratios cannot be explained by current models.
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    ABSTRACT: We found presolar SiC grains of Type AB with 32S enrichments. It is likely that these grains originate from born-again AGB stars.
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    ABSTRACT: We studied 14 presolar SiC mainstream grains for C-, Si-, and S-isotopic compositions and S elemental abundances. Ten grains have low levels of S contamination and CI chondrite-normalized S/Si ratios between 2 × 10−5 and 2 × 10−4. All grains have S-isotopic compositions compatible within 2σ of solar values. Their mean S isotope composition deviates from solar by at most a few percent, and is consistent with values observed for the carbon star IRC+10216, believed to be a representative source star of the grains, and the interstellar medium. The isotopic data are also consistent with stellar model predictions of low-mass asymptotic giant branch (AGB) stars. In a δ33S versus δ34S plot the data fit along a line with a slope of 1.8 ± 0.7, suggesting imprints from galactic chemical evolution. The observed S abundances are lower than expected from equilibrium condensation of CaS in solid solution with SiC under pressure and temperature conditions inferred from the abundances of more refractory elements in SiC. Calcium to S abundance ratios are generally above unity, contrary to expectations for stoichiometric CaS solution in the grains, possibly due to condensation of CaC2 into SiC. We observed a correlation between Mg and S abundances suggesting solid solution of MgS in SiC. The low abundances of S in mainstream grains support the view that the significantly higher abundances of excess 32S found in some Type AB SiC grains are the result of in situ decay of radioactive 32Si from born-again AGB stars that condensed into AB grains.
    02/2014; DOI:10.1111/maps.12449
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    Hayabusa 2014: Second Symposium of Solar System Materials; 01/2014
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    ABSTRACT: In-cloud production of sulfate modifies the aerosol size distribution, with important implications for the magnitude of indirect and direct aerosol cooling and the impact of SO2 emissions on the environment. We investigate which sulfate sources dominate the in-cloud addition of sulfate to different particle classes as an air parcel passes through an orographic cloud. Sulfate aerosol, SO2 and H2SO4 were collected upwind, in-cloud and downwind of an orographic cloud for three cloud measurement events during the Hill Cap Cloud Thuringia campaign in Autumn, 2010 (HCCT-2010). Combined SEM and NanoSIMS analysis of single particles allowed the δ34S of particulate sulfate to be resolved for particle size and type. The most important in-cloud SO2 oxidation pathway at HCCT-2010 was aqueous oxidation catalysed by transition metal ions (TMI catalysis), which was shown with single particle isotope analyses to occur primarily in cloud droplets nucleated on coarse mineral dust. In contrast, direct uptake of H2SO4(g) and ultrafine particulate were the most important sources modifying fine mineral dust, increasing its hygroscopicity and facilitating activation. Sulfate addition to "mixed" particles (secondary organic and inorganic aerosol) and coated soot was dominated by in-cloud aqueous SO2 oxidation by H2O2 and direct uptake of H2SO4(g) and ultrafine particle sulfate, depending on particle size mode and time of day. These results provide new insight into in-cloud sulfate production mechanisms, and show the importance of single particle measurements and models to accurately assess the environmental effects of cloud processing.
    Atmospheric Chemistry and Physics 12/2013; 14(2). DOI:10.5194/acpd-14-2935-2014 · 4.88 Impact Factor
  • Meteoritics & planetary science 10/2013; 49(9):n/a-n/a. DOI:10.1111/maps.12148 · 2.83 Impact Factor

Publication Stats

5k Citations
876.05 Total Impact Points

Institutions

  • 1970–2014
    • Max Planck Institute for Chemistry
      • Department of Particle Chemistry
      Mayence, Rheinland-Pfalz, Germany
  • 2012
    • Universität Stuttgart
      Stuttgart, Baden-Württemberg, Germany
    • Carnegie Institution for Science
      • Department of Terrestrial Magnetism
      Вашингтон, West Virginia, United States
  • 2011
    • The Police Academy of the Czech Republic in Prague
      Praha, Praha, Czech Republic
  • 1995–2009
    • Universität Bern
      • Physikalisches Institut
      Bern, BE, Switzerland
  • 1989–2000
    • Washington University in St. Louis
      • • Department of Chemistry
      • • Department of Physics
      San Luis, Missouri, United States
  • 1993–1996
    • University of Chicago
      • Enrico Fermi Institute
      Chicago, Illinois, United States
  • 1994
    • Naturhistorisches Museum Wien
      • Department of Mineralogy and Petrography
      Wien, Vienna, Austria