Browsing by Author "van Riessen, GA"
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- ItemHigh-speed free-run ptychography at the Australian Synchrotron(International Union of Crystallography, 2022-03) Jones, MWM; van Riessen, GA; Phillips, NW; Schrank, CE; Hinsley, GN; Afshar, N; Reinhardt, J; de Jonge, MD; Kewish, CMOver the last decade ptychography has progressed rapidly from a specialist ultramicroscopy technique into a mature method accessible to non-expert users. However, to improve scientific value ptychography data must reconstruct reliably, with high image quality and at no cost to other correlative methods. Presented here is the implementation of high-speed ptychography used at the Australian Synchrotron on the XFM beamline, which includes a free-run data collection mode where dead time is eliminated and the scan time is optimized. It is shown that free-run data collection is viable for fast and high-quality ptychography by demonstrating extremely high data rate acquisition covering areas up to 352 000 μm2 at up to 140 μm2 s-1, with 13x spatial resolution enhancement compared with the beam size. With these improvements, ptychography at velocities up to 250 μm s-1 is approaching speeds compatible with fast-scanning X-ray fluorescence microscopy. The combination of these methods provides morphological context for elemental and chemical information, enabling unique scientific outcomes. © The Authors - Open Access CC-By Licence
- ItemIn situ applications of soft x-ray ptychography(Australian Microscopy and Microanalysis Society, 2016-02-04) van Riessen, GA; James, M; van Riessen, A; Phillips, NW; de Jonge, MD; Kourousias, G; Giamoncelli, A; Bozzini, BCoherent diffractive imaging (CDI) with synchrotron X-ray beams allows extended objects to be characterised at high spatial resolution (<30 nm) and high energy resolution (0.1 eV). In an implementation of CDI known as ptychography, a far-field diffraction pattern is measured from many overlapping regions as the sample is scanned through a coherent X-ray beam. Quantitative images of an object are then obtained from the far-field intensity pattern through iterative reconstruction algorithms. This provides a unique method of studying the elemental and chemical-state distributions in relatively thick materials and their relationship to nanoscale morphology. The high coherent flux offered by synchrotron X-ray sources can also potentially allow high temporal resolution through the use of emerging detector technology and advanced image reconstruction algorithms. This in turn allows the nanoscale structure of functional materials to be studied under non-equilibrium real-time conditions. In this work, we review recent efforts to apply soft X-ray ptychography to in situ and operando applications at several synchrotron facilities. We emphasise studies of functional materials that are characterised by heterogeneity over a range of relevant length scales, including energy storage materials based on polypyrrole nanocomposites and inorganic, aluminosilicate based ceramics. Finally, a perspective on the future prospects of the method will be given, with particular attention to how experimental challenges can be overcome to achieve the spatiotemporal resolution limits defined by the available coherent flux from synchrotron light sources.
- ItemInvestigation and optimization of reactive ion etching of Si3N4 and polyphthalaldehyde for two-step gray scale fabrication of diffractive optics(AIP, 2019-11-18) Aminzadeh, A; Bose, M; Smith, D; Uddin, MH; Peele, AG; van Riessen, GANanofabrication of x-ray diffractive optics using electron beam lithography requires a complex process of electron exposure optimization and resist development. Thermal scanning probe lithography (TSPL) offers a high resolution, maskless, gray scale patterning method with reduced complexity. Thin diffractive optics with high efficiency for the extreme ultraviolet (EUV) and soft x-ray (SXR) photon range could be fabricated by combining TSPL with a single etching step if the TSPL resist, polyphthalaldehyde (PPA), can be used as an etch mask to direct-etch the pattern into a substrate using reactive ion etching. This condition critically depends on high etch selectivity between the substrate and the PPA, because TSPL resolution deteriorates as the PPA patterning depth increases beyond tens of nanometers. In this work, the authors have evaluated the etch selectivity for PPA and Si3N4 using SF6/C4F8 gases and the influence of process parameters, including gas flow rate, vacuum pressure, radio frequency bias power, and inductively coupled plasma power. The experimental results indicate that an etch selectivity of 7 (Si3N4:PPA) is achievable, and the authors demonstrate that diffractive optics for EUV/SXR can be fabricated in only two steps. © 2023 AIP
- ItemPolycrystalline materials analysis using the Maia pixelated energy-dispersive x-ray area detector(Cambridge University Press, 2017-09-26) Kirkwood, HJ; De Jonge, MD; Howard, DL; Ryan, CG; van Riessen, GA; Hofmann, F; Rowles, MR; Paradowska, AM; Abbey, BElemental, chemical, and structural analysis of polycrystalline materials at the micron scale is frequently carried out using microfocused synchrotron X-ray beams, sometimes on multiple instruments. The Maia pixelated energy-dispersive X-ray area detector enables the simultaneous collection of X-ray fluorescence (XRF) and diffraction because of the relatively large solid angle and number of pixels when compared with other systems. The large solid angle also permits extraction of surface topography because of changes in self-absorption. This work demonstrates the capability of the Maia detector for simultaneous measurement of XRF and diffraction for mapping the short- and long-range order across the grain structure in a Ni polycrystalline foil. Copyright © International Centre for Diffraction Data 2017
- ItemPropagation-based x-ray phase contrast imaging using an iterative phase diversity technique(Institute of Physics, 2018-02-15) Carroll, AJ; van Riessen, GA; Balaur, E; Dolbnya, IP; Tran, GN; Peele, AGThrough the use of a phase diversity technique, we demonstrate a near-field in-line x-ray phase contrast algorithm that provides improved object reconstruction when compared to our previous iterative methods for a homogeneous sample. Like our previous methods, the new technique uses the sample refractive index distribution during the reconstruction process. The technique complements existing monochromatic and polychromatic methods and is useful in situations where experimental phase contrast data is affected by noise. © The Authors - Open Access CC-BY 3.0 licence
- ItemSimultaneous reconstruction and structural fitting of the complex atomic fine structure of copper and iron(Australian Institute of Physics, 2022-12-11) Di Pasquale, P; Tran, CQ; Chantler, CT; Barnea, Z; Kirk, T; Dao, MN; Balaur, E; van Riessen, GA; Hinsley, GN; Jallandhra, A; Ceddia, J; Rogers, J; Kewish, CM; Paterson, DJ; Reinhardt, J; Kirby, N; Mudie, STA novel technique for determining complex atomic fine structure will be described. Exciting applications of the technique such as a phase analogue to x-ray absorption fine structure applications will also be discussed.
- ItemSimultaneous X-ray diffraction, crystallography and fluorescence mapping using the Maia detector(Elsevier, 2018-02-01) Kirkwood, HJ; de Jonge, MD; Muránsky, O; Hofmann, F; Howard, DL; Ryan, CG; van Riessen, GA; Rowles, MR; Paradowska, AM; Abbey, BInteractions between neighboring grains influence the macroscale behavior of polycrystalline materials, particularly their deformation behavior, damage initiation and propagation mechanisms. However, mapping all of the critical material properties normally requires that several independent measurements are performed. Here we report the first grain mapping of a polycrystalline foil using a pixelated energy-dispersive X-ray area detector, simultaneously measuring X-ray fluorescence and diffraction with the Maia detector in order to determine grain orientation and estimate lattice strain. These results demonstrate the potential of the next generation of X-ray area detectors for materials characterization. By scanning the incident X-ray energy we investigate these detectors as a complete solution for simultaneously mapping the crystallographic and chemical properties of the sample. The extension of these techniques to broadband X-ray sources is also discussed. © 2017 Acta Materialia Inc. Published by Elsevier Ltd.
- ItemSimultaneously localising biometals within the high resolution ultrastructure of whole C. elegans(Australian Microscopy and Microanalysis Society, 2016-02-04) Jones, MWM; McColl, G; van Riessen, GA; Phillips, NW; Vine, D; Abbey, B; de Jonge, MDPtychography is a coherent diffraction imaging method where multiple overlapping diffraction frames are combined, providing high resolution images of the electron density of extended objects. Recently, X-ray ptychography has seen many efficiency improvements that allow large areas to be imaged rapidly, making simultaneous X-ray ptychography and fluorescence microscopy experimentally viable. Here we use simultaneous X-ray fluorescence microscopy and ptychography to image entire C. elegans, with sub-micron and sub 100 nm elemental and ultrastructure resolutions respectively. Rapid data collection allowed the entire 1 mm long animal to be imaged in only a few hours. With the information from both techniques, the elemental maps can be viewed in the context of the high resolution ultrastructure, allowing further insights into the localisation of the fluorescent signal.