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Laboratory X-ray microscopy for high-resolution imaging of environmental colloid structure
KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.ORCID-id: 0000-0003-2723-6622
KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
Vise andre og tillknytning
2012 (engelsk)Inngår i: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 329, nr SI, s. 26-31Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Transmission X-ray microscopy is a uniquely suited technique for studies of environmental colloids since it allows imaging in aqueous media with high spatial resolution, presently down to the 20 nm range. Such nanoscale morphological description of these high-specific-surface-area compounds show promise for improved understanding of soils, sediments or groundwater aquifers. However, present high-quality X-ray microscopes are located at synchrotron radiation facilities resulting in limited applicability and accessibility for colloid scientists. Here we investigate the applicability of a laboratory-scale transmission X-ray microscope for studies of colloids of the environment. The microscope is based on a laser-plasma source in combination with multilayer and zone plate optics. Samples are held at atmospheric pressure in their natural wet state. We show images revealing the nano-scale morphology of the clay nontronite, soils such as chernozem and luvisol, and the mineral hematite, an iron oxide. Comparative studies of dried substances clearly show the need for imaging in the wet state. The image quality approaches that of synchrotron-based microscopes, albeit at longer exposure times. Stereo imaging is investigated as a means for giving 3D information with shorter exposure times than tomography requires. Finally the future development of the laboratory X-ray microscope is discussed, especially with regard to the reduction of exposure times.

sted, utgiver, år, opplag, sider
2012. Vol. 329, nr SI, s. 26-31
Emneord [en]
X-ray microscopy, Laser plasma, Diffractive optics, Laboratory scale, environmental colloids, soils
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-26952DOI: 10.1016/j.chemgeo.2011.07.012ISI: 000310125000005Scopus ID: 2-s2.0-84866508020OAI: oai:DiVA.org:kth-26952DiVA, id: diva2:373137
Forskningsfinansiär
Swedish Research Council
Merknad

QC 20121127

Tilgjengelig fra: 2010-11-30 Laget: 2010-11-30 Sist oppdatert: 2017-12-12bibliografisk kontrollert
Inngår i avhandling
1. Phase-Contrast and High-Resolution Optics for X-Ray Microscopy
Åpne denne publikasjonen i ny fane eller vindu >>Phase-Contrast and High-Resolution Optics for X-Ray Microscopy
2010 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

X-ray microscopy is a well-established technique for nanoscale imaging. Zone plates are used as microscope objectives and provide high resolution, approaching 10 nm, currently limited by fabrication issues. This Thesis presents zone plate optics that achieve either high resolution or phase contrast in x-ray microscopy. The high-resolution optics use high orders of the zone plate, which alleviates the demands on fabrication, and the phase-contrast optics are single-element diffractive optical elements that produce contrast by Zernike or differential-interference contrast methods. The advantage of phase contrast in x-ray microscopy is shorter exposure times, and is crucial in the hard x-ray regime. Microscopy in the absorption‑contrast region of the water-window (2.34 - 4.37 nm) also benefits from these optics. The development of the optics for a laboratory soft x-ray microscope spans from theoretical and numerical analysis of coherence and stray light to experimental implementation and testing. The laboratory microscope uses laser-produced plasma-sources in the water-window and is unique in its design and performance. It will be shown that the laboratory microscope in its current form is a user-oriented and stable instrument, and has been used in a number of applications. The implementation of a cryogenic sample stage for tomographic imaging of biological samples in their natural environment has enabled applications in biology, and 3D x-ray microscopy of cells was performed for the first time with a laboratory instrument.

 

sted, utgiver, år, opplag, sider
Stockholm: KTH, 2010. s. x, 61
Serie
Trita-FYS, ISSN 0280-316X ; 72
Emneord
Microscopy, X-ray optics, X-ray microscopy, Soft X-ray physics
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-26781 (URN)978-91-7415-834-2 (ISBN)
Disputas
2010-12-17, FD5, Roslagstullsbacken 21, Stockholm, 15:42 (engelsk)
Opponent
Veileder
Merknad
QC 20101130Tilgjengelig fra: 2010-11-30 Laget: 2010-11-26 Sist oppdatert: 2010-11-30bibliografisk kontrollert
2. Laboratory soft x-ray microscopy and tomography
Åpne denne publikasjonen i ny fane eller vindu >>Laboratory soft x-ray microscopy and tomography
2011 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Soft x-ray microscopy in the water-window (λ = 2.28 nm – 4.36 nm) is based on zone-plate optics and allows high-resolution imaging of, e.g., cells and soils in their natural or near-natural environment. Three-dimensional imaging is provided via tomographic techniques, soft x-ray cryo tomography. However, soft x-ray microscopes with such capabilities have been based on large-scale synchrotron x‑ray facilities, thereby limiting their accessibility for a wider scientific community.

This Thesis describes the development of the Stockholm laboratory soft x-ray microscope to three-dimensional cryo tomography and to new optics-based contrast mechanisms. The microscope relies on a methanol or nitrogen liquid-jet laser-plasma source, normal-incidence multilayer or zone-plate condenser optics, in-house fabricated zone-plate objectives, and allows operation at two wavelengths in the water-window, λ = 2.48 nm and λ = 2.48 nm. With the implementation of a new state-of-the-art normal-incidence multilayer condenser for operation at λ = 2.48 nm and a tiltable cryogenic sample stage the microscope now allows imaging of dry, wet or cryo-fixed samples. This arrangement was used for the first demonstration of laboratory soft x-ray cryo microscopy and tomography. The performance of the microscope has been demonstrated in a number of experiments described in this Thesis, including, tomographic imaging with a resolution of 140 nm, cryo microscopy and tomography of various cells and parasites, and for studies of aqueous soils and clays. The Thesis also describes the development and implementation of single-element differential-interference and Zernike phase-contrast zone-plate objectives. The enhanced contrast provided by these optics reduce exposure times or lowers the dose in samples and are of major importance for harder x-ray microscopy. The implementation of a high-resolution 50 nm compound zone-plate objective for sub-25-nm resolution imaging is also described. All experiments are supported by extensive numerical modelling for improved understanding of partially coherent image formation and stray light in soft x-ray microscopes. The models are useful tools for studying effects of zone plate optics or optical design of the microscope on image formation and quantitative accuracy in soft x-ray tomography.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2011. s. x, 76
Serie
Trita-FYS, ISSN 0280-316X ; 2011:03
Emneord
Microscopy, X-ray optics, Diffractive optics, Zone plates, X-ray microscopy, Soft X-ray physics, Tomography
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-29950 (URN)978-91-7415-874-8 (ISBN)
Disputas
2011-02-25, FB42, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (engelsk)
Opponent
Veileder
Merknad
QC 20110221Tilgjengelig fra: 2011-02-21 Laget: 2011-02-18 Sist oppdatert: 2011-02-21bibliografisk kontrollert

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