Development of X-ray photoemission electron microscopy (X-PEEM) at the SRS

Smith, Andrew D.; Cressey, G.; Schofield, P. F.; Cressey, B. A.

doi:10.1107/s0909049597015811

Cited by 8 publications

(5 citation statements)

References 10 publications

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“…1995). The potential for XPEEM to be applied to geomaterials was explored by Smith et al. (1998, 2004), using an in‐house prototype PEEM and by Schofield et al.…”

mentioning

confidence: 99%

“…Within mineralogy, bulk 2p XAS of powdered samples was developed for fingerprinting and quantifying oxidation states and site symmetries of geomaterials (de Groot et al 1992, van der Laan et al 1992, Cressey et al 1993, Pattrick et al 1993, Schofield et al 1993, 1995a, b, Henderson et al 1995, Li et al 1995. The potential for XPEEM to be applied to geomaterials was explored by Smith et al (1998Smith et al ( , 2004, using an in-house prototype PEEM and by Schofield et al (2002) zone textured regions indicating increased oxidation at the edges of these zones. The spatial resolution of the XPEEM achieved was between 110 and 150 nm, which precluded the study of either the previously reported 10 nm precipitates of tetrataenite within the bulk taenite or any antitaenite.…”

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confidence: 99%

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X‐ray Spectromicroscopy of Mineral Intergrowths in the Santa Catharina Meteorite

Schofield

Smith

Mosselmans

et al. 2010

Geostandard Geoanalytic Res

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This work describes the application of microfocus X‐ray absorption spectroscopy (XAS) and X‐ray photo‐emission electron microscopy (XPEEM) to the study of the complex mineralogical intergrowths within the Santa Catharina meteorite. The Santa Catharina meteorite of this study (BM52283 from the meteorite collection of the Natural History Museum, London, UK) primarily comprises a taenite bulk host phase (Fe:Ni ratio = 70.9 ± 0.8%:29.1 ± 0.8%) with a set of oxide‐bearing cloudy zone textured regions (Fe:Ni:O ratio = 40.4 ± 0.3%:49.0 ± 0.7%:10.6 ± 0.8% at the core and Fe:Ni:O ratio = 34.4 ± 1.5%:42.7 ± 0.6%:22.9 ± 1.8% towards the rims) and numerous schreibersite (Fe:Ni:P ratio = 38.6 ± 1.6%:38.4 ± 0.9%:23.0 ± 0.5%) inclusions. Between the schreibersite and the taenite are rims up to 50 μm across of Ni‐rich kamacite (Fe:Ni ratio = 93.4 ± 0.4%:6.6 ± 0.5%). No chemical zoning or spatial variations in the Fe and Ni speciation was observed within either the schreibersite or the kamacite phases. The oxide‐bearing cloudy zone textured regions mostly comprise metallic Fe–Ni alloy, predominantly tetrataenite. Within the oxide phases, the Fe is predominantly, but not entirely, tetrahedrally co‐ordinated Fe3+ and the Ni is octahedrally co‐ordinated Ni2+. Structural analysis supports the suggestion that non‐stoichiometric Fe2NiO4 trevorite is the oxide phase. The trevorite:tetrataenite ratio increases at the edges of the oxide‐bearing cloudy zone textured regions indicating increased oxidation at the edges of these zones. The spatial resolution of the XPEEM achieved was between 110 and 150 nm, which precluded the study of either the previously reported ∼ 10 nm precipitates of tetrataenite within the bulk taenite or any antitaenite.

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“…1995). The potential for XPEEM to be applied to geomaterials was explored by Smith et al. (1998, 2004), using an in‐house prototype PEEM and by Schofield et al.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

X‐ray Spectromicroscopy of Mineral Intergrowths in the Santa Catharina Meteorite

Schofield

Smith

Mosselmans

et al. 2010

Geostandard Geoanalytic Res

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“…The beamline has a spherical-grating monochromator, yielding very high photon flux (2 × 10 12 photons S −1 at 800 eV in a 0.4 mm × 0.2 mm) with spatial resolution better than 50 nm. [26,27] The emitted photoelectrons were accelerated toward an electron lens column and projected onto an aluminum coated yttrium aluminium garnet crystal screen. The real-time, sample surface im-ages were acquired by a charge coupled device detector mounted behind the screen in total electron yield mode.…”

Section: Methodsmentioning

confidence: 99%

Enhanced Visualization and Interpretation of XMCD‐PEEM Data Using SOM‐RPM Machine Learning

Wong,

Harmer,

Gardner

et al. 2023

Adv Materials Inter

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Photoemission electron microscopy (PEEM) is a powerful technique for surface characterization that provides detailed information on the chemical and structural properties of materials at the nanoscale. In this study, the potential is explored using a machine learning algorithm called self‐organizing map with a relational perspective map (SOM‐RPM) for visualizing and analyzing complex PEEM‐generated datasets. The application of SOM‐RPM is demonstrated using synchrotron‐based X‐ray magnetic circular dichroism (XMCD)‐PEEM data acquired from a pyrrhotite sample. Traditional visualization approaches for XMCD‐PEEM data may not fully capture the complexity of the sample, especially in the case of heterogeneous materials. By applying SOM‐RPM to the XMCD‐PEEM data, a colored topographic map is created that represents the spectral similarities and dissimilarities among the pixels. This approach allows for a more intuitive and easily interpretable representation of the data without the need of data binning or spectral smoothing. The results of the SOM‐RPM analysis are compared to the conventional visualization approach, highlighting the advantages of SOM‐RPM in revealing features that are not readily observable in the conventional method. This study suggests that the SOM‐RPM approach can be used complimentarily for other PEEM‐based measurements, such as core level and valence band X‐ray photoelectron spectroscopy.

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“…Another advantage of PEEM is the ability to easily extract data from any given point on the surface, allowing one to investigate how a surface changes with distance from a feature or grain interface. PEEM has been applied to heterogeneous minerals by Smith et al (1998) and Schmidt et al (2001) to image the distribution of mineral phases across natural samples. However, these studies were concerned with identification of mineral phases within heterogeneous samples, rather than the study of surface processes.…”

Section: Introductionmentioning

confidence: 99%

Synchrotron PEEM and ToF-SIMS study of oxidized heterogeneous pentlandite, pyrrhotite and chalcopyrite

2010

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Synchrotron-based photoemission electron microscopy (PEEM; probing the surface region) and time-of-flight secondary ion mass spectrometry (ToF-SIMS; probing the uppermost surface layer) have been used to image naturally heterogeneous samples containing chalcopyrite (CuFeS(2)), pentlandite [(Ni,Fe)(9)S(8)] and monoclinic pyrrhotite (Fe(7)S(8)) both freshly polished and exposed to pH 9 KOH for 30 min. PEEM images constructed from the metal L(3) absorption edges were acquired for the freshly prepared and solution-exposed mineral samples. These images were also used to produce near-edge X-ray absorption fine-structure spectra from regions of the images, allowing the chemistry of the surface of each mineral to be interrogated, and the effect of solution exposure on the mineral surface chemistry to be determined. The PEEM results indicate that the iron in the monoclinic pyrrhotite oxidized preferentially and extensively, while the iron in the chalcopyrite and pentlandite underwent only mild oxidation. The ToF-SIMS data gave a clearer picture of the changes happening in the uppermost surface layer, with oxidation products being observed on all three minerals, and significant polysulfide formation and copper activation being detected for pyrrhotite.

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Development of X-ray photoemission electron microscopy (X-PEEM) at the SRS

Cited by 8 publications

References 10 publications

X‐ray Spectromicroscopy of Mineral Intergrowths in the Santa Catharina Meteorite

X‐ray Spectromicroscopy of Mineral Intergrowths in the Santa Catharina Meteorite

Enhanced Visualization and Interpretation of XMCD‐PEEM Data Using SOM‐RPM Machine Learning

Synchrotron PEEM and ToF-SIMS study of oxidized heterogeneous pentlandite, pyrrhotite and chalcopyrite

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