P. Hoppe

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

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Publications (344)803.48 Total impact

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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 of the United States of America. 10/2014;
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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. · 2.80 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. · 31.03 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. · 3.88 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; · 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.
    03/2014; 14(8).
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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.
    02/2014;
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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.
    02/2014;
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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).
    02/2014;
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    ABSTRACT: Presolar SiC mainstream grains have close to solar S-isotopic ratios and low S abundances that can be reproduced by equilibrium condensation calculations.
    02/2014;
  • 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.
    02/2014;
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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 01/2014; 140:577–605. · 3.88 Impact Factor
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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.
    12/2013; 14(2).
  • Meteoritics & planetary science 10/2013; · 2.80 Impact Factor
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    ABSTRACT: We report C, Si, and S isotope measurements on 34 presolar silicon carbide grains of Type AB, characterized by 12C/13C < 10. Nitrogen, Mg-Al-, and Ca-Ti-isotopic compositions were measured on a subset of these grains. Three grains show large 32S excesses, a signature that has been previously observed for grains from supernovae (SNe). Enrichments in 32S may be due to contributions from the Si/S zone and the result of S molecule chemistry in still unmixed SN ejecta or due to incorporation of radioactive 32Si from C-rich explosive He shell ejecta. However, a SN origin remains unlikely for the three AB grains considered here, because of missing evidence for 44Ti, relatively low 26Al/27Al ratios (a few times 10-3), and radiogenic 32S along with low 12C/13C ratios. Instead, we show that born-again asymptotic giant branch (AGB) stars that have undergone a very-late thermal pulse (VLTP), known to have low 12C/13C ratios and enhanced abundances of the light s-process elements, can produce 32Si, which makes such stars attractive sources for AB grains with 32S excesses. This lends support to the proposal that at least some AB grains originate from born-again AGB stars, although uncertainties in the born-again AGB star models and possible variations of initial S-isotopic compositions in the parent stars of AB grains make it difficult to draw a definitive conclusion.
    The Astrophysical Journal 10/2013; 776(2). · 6.73 Impact Factor
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    ABSTRACT: This study presents high-precision isotope ratio-mass spectrometric measurements of isotopic fractionation during oxidation of SO2 by OH radicals in the gas phase and H2O2 and transition metal ion catalysis (TMI-catalysis) in the aqueous phase. Although temperature dependence of fractionation factors was found to be significant for H2O2 and TMI-catalysed pathways, results from a simple 1D model revealed that changing partitioning between oxidation pathways was the dominant cause of seasonality in the isotopic composition of sulfate relative to SO2. Comparison of modelled seasonality with observations shows the TMI-catalysed oxidation pathway is underestimated by more than an order of magnitude in all current atmospheric chemistry models. The three reactions showed an approximately mass-dependent relationship between 33S and 34S. However, the slope of the mass-dependent line was significantly different to 0.515 for the OH and TMI-catalysed pathways, reflecting kinetic versus equilibrium control of isotopic fractionation. For the TMI-catalysed pathway, both temperature dependence and 33S/34S relationship revealed a shift in the rate-limiting reaction step from dissolution at lower temperatures to TMI-sulfite complex formation at higher temperatures. 1D model results showed that although individual reactions could produce D33S values between -0.15 and +0.2 permil, seasonal changes in partitioning between oxidation pathways caused average sulfate D33S values of 0 permil throughout the year.
    Environmental Science & Technology 09/2013; · 5.48 Impact Factor
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    ABSTRACT: We identified abundant (~100 ppm) presolar silicates and oxides in chondrule rims of three CR chondrites, indicating a nebular origin of the fine-grained material. High proportions of presolar silicates in the rims emphasize their primitive nature.
    Meteoritics and Planetary Science Supplement. 09/2013;
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    ABSTRACT: We report on the search for traces of the Chicxulub bolide in the K-Pg bed drilled in the western tropical Atlantic, using advanced separation techniques and microanalytical tools with high spatial resolution.
    Meteoritics and Planetary Science Supplement. 09/2013;
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    E. Zinner, P. Hoppe, M. Pignatari
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    ABSTRACT: Presolar SiC grains of type C have large ^29Si and ^30Si excesses as well as ^32S excesses. We propose that these ^32S excesses originate from the decay of short-lived ^32Si produced by high neutron densities (neutron burst) in core-collapse supernovae.
    Meteoritics and Planetary Science Supplement. 09/2013;
  • W. Fujiya, P. Hoppe, U. Ott
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    ABSTRACT: We measured Li and B isotopic ratios in asteroidal regolith grains returned by the Hayabusa mission. We found significant depletion in boron-11 on their surfaces, which can be interpreted as a solar wind component.
    Meteoritics and Planetary Science Supplement. 09/2013;

Publication Stats

3k Citations
803.48 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
  • 2011
    • The Police Academy of the Czech Republic in Prague
      Praha, Praha, Czech Republic
  • 2010
    • Imperial College London
      • Department of Earth Science and Engineering
      London, ENG, United Kingdom
  • 1995–2010
    • Universität Bern
      • Physikalisches Institut
      Bern, BE, Switzerland
    • Washington University in St. Louis
      • Department of Physics
      San Luis, Missouri, United States
  • 2007
    • State University of New York at Plattsburgh
      • Department of Physics
      Plattsburgh, New York, United States
    • University of California, Los Angeles
      • Department of Earth and Space Sciences (ESS)
      Los Angeles, CA, United States
    • NASA
      Washington, West Virginia, United States
  • 2006
    • Carnegie Institution for Science
      • Department of Terrestrial Magnetism
      Washington, WV, United States
  • 2005
    • University of Houston
      Houston, Texas, United States
  • 1996
    • University of Münster
      • Institute of Planetology
      Muenster, North Rhine-Westphalia, Germany
  • 1993–1996
    • University of Chicago
      • Enrico Fermi Institute
      Chicago, Illinois, United States