Ratios of ferrous to ferric iron from nanometre-sized areas in minerals

Garvie, L. A. J.; Buseck, Peter R.

doi:10.1038/25334

Cited by 210 publications

(133 citation statements)

References 24 publications

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“…Energy-dispersive spectra were acquired with a Noran EDS detector attached to a 200 keV JEOL 2200F TEM and quantified with standardless routines in the Noran Vantage software. Electron energy-loss spectra were acquired using a Gatan 766 DigiPEELS spectrometer attached to a 100 keV Philips 400 FEG TEM (see Garvie and Buseck 1998;Garvie et al 2004; for details). High-resolution scanning electron microscope (SEM) images were acquired with a Hitachi S-4700 FEG-SEM.…”

Section: Methodsmentioning

confidence: 99%

Polyhedral serpentine grains in CM chondrites

Zega¹,

Garvie²,

Dódony³

et al. 2006

Meteoritics &Amp; Planetary Science

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Polyhedral serpentine grains in CM chondritesAbstract-We used high-resolution transmission electron microscopy (HRTEM), electron tomography, electron energy-loss spectroscopy (EELS), and energy-dispersive spectroscopy (EDS) to investigate the structure and composition of polyhedral serpentine grains that occur in the matrices and fine-grained rims of the Murchison, Mighei, and Cold Bokkeveld CM chondrites. The structure of these grains is similar to terrestrial polygonal serpentine, but the data show that some have spherical or subspherical, rather than cylindrical morphologies. We therefore propose that the term polyhedral rather than polygonal be used to describe this material. EDS shows that the polyhedral grains are rich in Mg with up to 8 atom% Fe. EELS indicates that 70% of the Fe occurs as Fe 3+ . Alteration of cronstedtite on the meteorite parent body under relatively oxidizing conditions is one probable pathway by which the polyhedral material formed. The polyhedral grains are the endmember serpentine in a mineralogic alteration sequence for the CM chondrites.

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Section: Methodsmentioning

confidence: 99%

Polyhedral serpentine grains in CM chondrites

Zega¹,

Garvie²,

Dódony³

et al. 2006

Meteoritics &Amp; Planetary Science

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“…In this case, the fuel ow was seeded with iron pentacarbonyl. Although micro EELS examination of the individual crystals was not able to resolve the L 2 3 peak that could potentially speciate the oxidation state of the iron (as shown by van Aken et al (1998) and Garvie and Buseck (1998) in minerals), it was, nonetheless, able to identify the presence of iron and oxygen ( Figure 6) in the ratio of approximately 2:3 that was expected of Fe 2 O 3 .…”

Section: Resultsmentioning

confidence: 99%

Synthesis of an Ultrafine Iron and Soot Aerosol for the Evaluation of Particle Toxicity

Yang¹,

Teague²,

Pinkerton³

et al. 2001

Aerosol Science and Technology

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A diffusion ame system was used to generate an aerosol of soot and iron oxide. The primary fuel was ethylene. Iron was introduced by passing ethylene over liquid iron pentacarbonyl. The aerosol emission from the ame was diluted by secondary air to a level that could be used in animal exposure studies. The system was designed to operate at a constant soot production rate while the iron loading was varied from 0 to 50 ¹g m 3 in the diluted post ame gases. The impact of the iron on soot production was counteracted by the addition of acetylene to the fuel. Particles were collected on carbon grids and were examined via transmission electron microscopy. Electron energy loss spectroscopy was employed to characterize the aerosol. A differential mobility analyzer was used to measure the size distribution of the aerosol. The iron particles were typically 40 nm in diameter and often appeared in isolation from the soot aerosol, suggesting that either they were not formed concurrently with the soot or they remained after oxidation of the surrounding soot. Samples collected from within the ame, and downstream of the ame, indicated that the iron may have been present as very small particles comingled with the soot. The iron particles apparently melted and coalesced as they passed through the high temperature ame tip. Crystallization of the iron proceeded as the post ame gases cooled by mixing with external air. The ame system was shown to be capable of consistently producing steady concentrations of soot and iron for delivery to animals, without the confounding presence of toxic gaseous compounds.

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“…Chan et al (7) used STXM to show that microbially generated iron-oxyhydroxide filaments contain polysaccharides, suggesting that the polysaccharides are the mineral structure-directing component. It is possible to deduce not only oxidation state but ligand arrangement, and, in some cases, ligand identity from details of the metal 2p NEXAFS fine structure (19)(20)(21). Pecher et al (22) used STXM and linear regression procedures to perform Mn speciation from selected areas on bacteria-produced nodules using the Mn 2p absorption edge.…”

Section: Introductionmentioning

confidence: 99%

Speciation and Quantitative Mapping of Metal Species in Microbial Biofilms Using Scanning Transmission X-ray Microscopy

Dynes

Tyliszczak

Araki

et al. 2006

Environ. Sci. Technol.

129

142

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A scanning transmission X-ray microscope illuminated with synchrotron light was used to investigate the speciation and spatial distributions of metals in a microbial biofilm cultivated from river water. Metal 2p absorption edge signals were used to provide metal speciation (through shapes of the absorption spectra) and quantitative spatial distributions of the metal species. This paper presents sample data and describes methods for extracting quantitative maps of metal species from image sequences recorded in the region of the metal 2p edges. Comparisons were made with biochemical characterization of the same region using images recorded at the C 1s and O 1s edges. The method is applied to detailed quantitative analysis of ferrous and ferric iron in a river biofilm, in concert with mapping Ni-(II) and Mn(II) species in the same region. The distributions of the metal species are discussed in the context of the biofilm structure. These results demonstrate that soft X-ray STXM measurements at the metal 2p absorption edges can be used to speciate metals and to provide quantitative spatial distribution maps for metal species in environmental samples with 50 nm spatial resolution.

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Ratios of ferrous to ferric iron from nanometre-sized areas in minerals

Cited by 210 publications

References 24 publications

Polyhedral serpentine grains in CM chondrites

Polyhedral serpentine grains in CM chondrites

Synthesis of an Ultrafine Iron and Soot Aerosol for the Evaluation of Particle Toxicity

Speciation and Quantitative Mapping of Metal Species in Microbial Biofilms Using Scanning Transmission X-ray Microscopy

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