X-ray Absorption Spectroscopic Microscopy: From the Micro- to the Nanoscale

Schroer, Christian G.; Grunwaldt, Jan‐Dierk

doi:10.1080/08940880902813741

Cited by 6 publications

(6 citation statements)

References 34 publications

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“…Recent progress has led to the development and application of the non‐invasive techniques mentioned above (X‐ray tomography, micro‐X‐ray fluorescence tomography) and MRI,15 tomographic energy‐dispersive diffraction imaging16 and XAS tomography 3c. 5, 17 In addition, microspectroscopic techniques have been applied by Weckhuysen and co‐workers3b to study different preparation steps, including non‐dried and non‐calcined samples. Despite the use of techniques such as Raman, UV/Vis and IR microspectroscopy and scanning electron microscopy (SEM), which usually require cleavage of the catalyst bodies along their z ‐axis, a much better understanding of the impregnation process could be achieved.…”

Section: Imaging Catalytic Reactors and Catalyst Bodies: Catalyst mentioning

confidence: 99%

“…It should also be noted that the spectral resolution of 50–100 μm currently offered by UV/Vis, Raman and MRI should be improved. One possibility is to use full‐field or scanning X‐ray microscopy, which provides a spectral resolution of a few μm or less3c,e, 5, 17, 24 and is complementary to tomographic energy‐dispersive diffraction imaging, which requires the presence of crystalline particles. Very recent studies in this direction have been performed by using computed tomography (CT) on Ni/Al 2 O 3 catalysts for CO methanation by synchrotron μ‐XRD‐CT and μ‐absorption‐CT 25.…”

Section: Imaging Catalytic Reactors and Catalyst Bodies: Catalyst mentioning

confidence: 99%

“…Despite the development of a number of methods for the structural identification of catalysts under reaction conditions1g, 4 the direct imaging of catalysts during reactions, both at the macro‐ and at the micro‐scale, is still in its infancy 3b,e. 5 Such “imaging at work” is essential because nanoscale particles are highly dynamic under reaction conditions and a change in reaction gas atmosphere can induce both morphological changes and the migration of active centres 1d–f. 6 Techniques are required to follow such changes, both in a time‐resolved manner and with sufficient spatial resolution, ideally in three dimensions.…”

Section: Introduction: Setting the Scenementioning

confidence: 99%

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Imaging Catalysts at Work: A Hierarchical Approach from the Macro‐ to the Meso‐ and Nano‐scale

2012

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This review highlights the importance of developing multi‐scale characterisation techniques for analysing operating catalysts in their working environment. We emphasise that a hierarchy of in situ techniques that provides macro‐, meso‐ and nano‐scale information is required to elucidate and optimise catalyst performance fully. This combined methodology should ideally embrace spatially resolved and spatio‐temporal monitoring of a) the structure, catalytic activity, temperature and heat/mass transfer pattern in axial and radial directions in real reactors, b) the structure and temperature/heat/mass transport gradients in shaped catalysts and catalyst grains and c) meso‐ and nano‐scale information about particles and clusters, whose physical and electronic properties are linked directly to the micro‐kinetic behaviour of the catalysts. Techniques such as X‐ray diffraction (XRD), infrared (IR), Raman, X‐ray photoelectron spectroscopy (XPS), UV/Vis, and X‐ray absorption spectroscopy (XAS), which have mainly provided global atomic scale information, are being developed to provide the same information on a more local scale, often with sub‐second time resolution. X‐ray microscopy, both in the soft and more recently in the hard X‐ray regime, allows two‐ and three‐dimensional information to be collected down to 10 nm spatial resolution in a gas atmosphere or liquid, although this improvement is at the expense of temporal resolution. Electron microscopy, which provides excellent local atomic scale structural and spectroscopic information, is being developed towards tomographic imaging and realistic conditions, allowing gaps to be bridged in pressure, reaction conditions and length scales, up to the meso‐ and macro‐scale. In addition, new techniques such as single molecule fluorescence spectroscopy and non‐linear spectroscopic techniques are emerging. In this review, we discuss prospects for the development and combined application of both existing and new techniques for in situ catalyst characterisation.

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Section: Imaging Catalytic Reactors and Catalyst Bodies: Catalyst mentioning

confidence: 99%

Section: Imaging Catalytic Reactors and Catalyst Bodies: Catalyst mentioning

confidence: 99%

Section: Introduction: Setting the Scenementioning

confidence: 99%

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Imaging Catalysts at Work: A Hierarchical Approach from the Macro‐ to the Meso‐ and Nano‐scale

2012

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“…these data, the local absorption spectrum can be reconstructed for each pixel [1]. This technique is particularly useful in physical chemistry, e.g., in the study of catalysis, as it allows one to determine in-operando the local oxidation state of a catalyst inside a chemical reactor and learn about catalytic reactions and their kinetics [1,2,[32][33][34][35][36].…”

Section: Full-field Microscopymentioning

confidence: 99%

Hard X-ray Microscopy with Elemental, Chemical and Structural Contrast

et al. 2010

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We review hard X-ray microscopy techniques with a focus on scanning microscopy with synchrotron radiation. Its strength compared to other microscopies is the large penetration depth of hard x rays in matter that allows one to investigate the interior of an object without destructive sample preparation. In combination with tomography, local information from inside of a specimen can be obtained, even from inside special non-ambient sample environments. Different X-ray analytical techniques can be used to produce contrast, such as X-ray absorption, fluorescence, and diffraction, to yield chemical, elemental, and structural information about the sample, respectively. This makes X-ray microscopy attractive to many fields of science, ranging from physics and chemistry to materials, geo-, and environmental science, biomedicine, and nanotechnology. Our scanning microscope based on nanofocusing refractive X-ray lenses has a routine spatial resolution of about 100 nm and supports the contrast mechanisms mentioned above. In combination with coherent X-ray diffraction imaging, the spatial resolution can be improved to the 10 nm range. The current state-of-the-art of this technique is illustrated by several examples, and future prospects of the technique are given.

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“…Micro-X-ray fluorescence (μ-XRF) analysis 1 is applied in environmental sciences, 2,3 geological applications, 4,5 cultural heritage studies, 6 archeology, 7 and in the biomedical, 8,9 chemical, 10,11 and forensic 12 domains. Usually the related experiments are realized at advanced research facilities, i.e., third generation synchrotron sources, where the bright, coherent, polarized, energy-tunable, and monochromatic Xray beams can be used for fluorescence, scattering, diffraction, or absorption experiments.…”

Section: Introductionmentioning

confidence: 99%

Laboratory-based micro-X-ray fluorescence setup using a von Hamos crystal spectrometer and a focused beam X-ray tube

Kayser

Błachucki

Dousse

et al. 2014

Review of Scientific Instruments

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The high-resolution von Hamos bent crystal spectrometer of the University of Fribourg was upgraded with a focused X-ray beam source with the aim of performing micro-sized X-ray fluorescence (XRF) measurements in the laboratory. The focused X-ray beam source integrates a collimating optics mounted on a low-power micro-spot X-ray tube and a focusing polycapillary half-lens placed in front of the sample. The performances of the setup were probed in terms of spatial and energy resolution. In particular, the fluorescence intensity and energy resolution of the von Hamos spectrometer equipped with the novel micro-focused X-ray source and a standard high-power water-cooled X-ray tube were compared. The XRF analysis capability of the new setup was assessed by measuring the dopant distribution within the core of Er-doped SiO 2 optical fibers.

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X-ray Absorption Spectroscopic Microscopy: From the Micro- to the Nanoscale

Cited by 6 publications

References 34 publications

Imaging Catalysts at Work: A Hierarchical Approach from the Macro‐ to the Meso‐ and Nano‐scale

Imaging Catalysts at Work: A Hierarchical Approach from the Macro‐ to the Meso‐ and Nano‐scale

Hard X-ray Microscopy with Elemental, Chemical and Structural Contrast

Laboratory-based micro-X-ray fluorescence setup using a von Hamos crystal spectrometer and a focused beam X-ray tube

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