Browsing by Author "Klein, AR"
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- ItemFemtosecond laser fabrication of diffractive optics for spatial and spectral imaging at synchrotron infrared beamlines(Society of Photo-Optical Instrumentation Engineers (SPIE), 2021-03-06) Anand, V; Katkus, T; Ng, SH; Vongsvivut, JP; Maksimovic, J; Klein, AR; Bambery, KR; Lundgaard, S; Linklater, D; Ivanova, EP; Tobin, MJ; Juodkazis, SInfrared (IR) microspectroscopy is a powerful molecular fingerprinting tool widely used for the identification of structural and functional composition of biological and chemical samples. The IR microspectroscopy beamline at the Australian Synchrotron can be operated either with a single-point narrow-band mercury cadmium telluride (MCT) detector or a focal plane array (FPA) imaging detector with 64 × 64 pixels. For the implementation of indirect nonscanning imaging technology, the system was operated with the FPA detector. In this study, we propose an indirect IR imaging technique based on the principles of correlation optics using diffractive optical elements such as random pinhole array (RPA) and Fresnel zone plate (FZP). The spatial and spectral variations of point spread functions (PSFs) of the RPA and FZP were simulated for the synchrotron configuration. Intensity responses for 2D objects were simulated using the same simulation conditions and reconstructed using Lucy-Richardson algorithm. Fabrication of diffractive elements for IR wavelengths is often a challenging task as the IR transparent material substrates, such as barium fluoride and calcium fluoride, are highly susceptible to thermal shocks and brittle by nature. The diffractive elements were fabricated by ablating directly on a 100 nm thick gold coated substrate using femtosecond laser pulses. The simulation results and the fabrication outcomes demonstrate the feasibility of indirect imaging at the synchrotron IR beamline. © 2021 Society of Photo-Optical Instrumentation Engineers (SPIE)
- ItemFire-induced shifts in stalagmite organic matter mapped using synchrotron infrared microspectroscopy(Elsevier, 2024-09) McDonough, LK; Campbell, M; Treble, PC; Marjo, CE; Frisia, S; Vongsvivut, JP; Klein, AR; Kovacs-Kis, V; Baker, AAUnderstanding organic matter (OM) in cave mineral deposits (speleothems) is essential for interpreting land use and climatic changes, and the incorporation of trace elements associated with organic compounds. However, the sources and composition of OM in speleothems are poorly understood due to challenges associated with measuring OM at low concentrations and the destructive nature of most speleothem OM analysis techniques. Synchrotron Fourier-transform infrared (FTIR) microspectroscopy is a promising non-destructive technique that can be used to investigate stalagmite OM composition. We use FTIR to analyse vegetation, soil, calcium carbonate and ash end-members and demonstrate the use of Synchrotron infrared microspectroscopy (IRM) mapping to detect temporal changes in the OM composition of a stalagmite from a shallow cave in south-west Western Australia. Our analysis reveals predominant FTIR peaks in the stalagmite linked to amides and CH2 groups, suggesting potential microbial contributions, with smaller proportions of aromatic, CH3 and Cdouble bondO groups. High-resolution transmission electron microscopy revealed that this OM is likely hosted in sets of nanopores spaced hundreds of nanometers apart, aligned along calcite crystallographic orientations. Furthermore, we assess the impact of known wildfire events as discrete short term environmental changes on the stalagmite’s OM composition. The temporal variability in OM functional group composition after fires implies complex fire-soil-vegetation-microbial interactions. This research demonstrates the effectiveness of Synchrotron IRM mapping in providing insights into the short and long-term environmental influences on stalagmite OM composition. Expanding this research to other regions and climates could further enhance the interpretation of OM changes in speleothem-based palaeoclimate reconstructions. © Crown Copyright © 2024 Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
- ItemHigh-resolution macro ATR-FTIR chemical imaging capability at Australian Synchrotron Infrared Microspectroscopy (IRM) Beamline(Australian Nuclear Science and Technology Organisation, 2021-11-25) Vongsvivut, JP; Tobin, MJ; Klein, AR; Bambery, KRThis presentation aims to provide a summary on technical aspects and applications of our synchrotron macro ATR-FTIR microspectroscopy, unique to the Infrared Microspectroscopy (IRM) beamline at ANSTO–Australian Synchrotron.1 The device was developed by modifying the cantilever arm of a standard macro-ATR unit to accept Ge-ATR elements. Coupling synchrotron-IR beam to the Ge-ATR element (n=4), reduces the beam focus size by a factor of 4 (improving lateral resolution), and the mapping step size by 4 times relative to the stage step motion. As a result, the macro ATR-FTIR measurement at our IRM beamline can be performed at minimum projected aperture (sampling spot size) of 1-2 μm using a 20x objective, and minimum mapping step size of 250 nm, allowing high-resolution chemical imaging analysis with the resolution limit beyond those allowed for standard synchrotron-FTIR transmission and reflectance setups. The technique has facilitated many experiments in a diverse range of research disciplinary. Here, there will be presentations based on macro ATR-FTIR technique in archaeology, electrochemistry (battery), biomedical and forensic sciences. Apart from these, we will provide additional applications in the fields of food and pharmaceutical science,2-4 single-fibre analysis,5-6 and dentistry.7 References: [1] J. Vongsvivut, et al., Analyst 144, 10, 3226-323 (2019). [2] A.P. Pax, et al., Food Chemistry, 291, 214-222 (2019). [3] Y.P. Timilsena, et al., Food Chemistry, 275, 457-466 (2019). [4] D.M. Silva, et al., Journal of Colloid and Interface Science, 587, 499-509 (2021). [5] S. Nunna, et al., Journal of Materials Chemistry A, 5, 7372-7382 (2017). [6] C. Haynl, et al., Scientific Reports, 10, 17624 (2020). [7] P.V. Seredin, et al., International Journal of Molecular Sciences, 22, 6510 (2021). © 2021 The Authors
- ItemSingle-shot mid-infrared incoherent holography using Lucy-Richardson-Rosen algorithm(Institute of Optics and Electronics, Chinese Academy of Sciences, 2022-03-18) Anand, V; Han, Ml; Maksimovic, J; Ng, SH; Katkus, T; Klein, AR; Bambery, KR; Tobin, MJ; Vongsvivut, JP; Juodkazis, JIn recent years, there has been a significant transformation in the field of incoherent imaging with new possibilities of compressing three-dimensional (3D) information into a two-dimensional intensity distribution without two-beam interference (TBI). Most of the incoherent 3D imagers without TBI are based on scattering by a random phase mask exhibiting sharp autocorrelation and low cross-correlation along the depth. Consequently, during reconstruction, high lateral and axial resolutions are obtained. Imaging based on scattering requires an astronomical photon budget and is therefore precluded in many power-sensitive applications. In this study, a proof-of-concept 3D imaging method without TBI using deterministic fields has been demonstrated. A new reconstruction method called the Lucy-Richardson-Rosen algorithm has been developed for this imaging concept. We believe that the proposed approach will cause a paradigm-shift in the current state-of-the-art incoherent imaging, fluorescence microscopy, mid-infrared fingerprinting, astronomical imaging, and fast object recognition applications. © The Author(s) 2022. Open Access: This article is licensed under a Creative Commons Attribution 4.0 International License.
- ItemSpectroscopic analysis of age-related changes in the brain lateral ventricles during ageing(Australian Nuclear Science and Technology Organisation, 2021-11-24) Hollings, A; Hackett, MJ; Tobin, MJ; Klein, AR; Vongsvivut, JP; de Jonge, MD; Bone, S; Webb, S; Lam, V; Takechi, R; Mamo, JAlzheimer’s disease is the most common form of dementia and poses significant health and economic concerns. Currently, the disease has no cure, and it is expected that over 1 million people could be affected by 2058 in Australia alone. The content and distribution of metals such as Fe, Cu, Zn is known to change in the ageing brain and thus, increased understanding of the mechanistic role of metal dis-homeostasis may illuminate new therapeutic strategies. The brain lateral ventricles, which play a role in controlling metal and ion transport, have shown increasing levels of copper surrounding their walls with ageing. As a redox active metal, copper can induce oxidative stress which is a process that occurs during Alzheimer’s disease onset and progression. Our research group has been interested in determining whether the age-related elevation of copper surrounding the lateral ventricles is inducing oxidative stress in that region. In this study, we have utilised X-Ray Absorption Spectroscopy (XAS) at the Stanford Synchrotron Radiation Lightsource to analyse different chemical forms of sulfur and measure oxidative stress by analysis of disulfides. Additionally, we used the infrared microscopy beamline at the Australian Synchrotron to identify whether any other markers of oxidative stress were present around the ventricles. Further insights into metal dis-homeostasis and its influence on other biochemical pathways, may help to reveal some of the neurochemical mechanisms involved in progression of Alzheimer’s disease. In turn, this may help pave the way for potential preventative or therapeutic models.
- ItemX-ray methods to investigate nutrient cycling in the subsurface(American Geophysical Union (AGU), 2021-12-18) Bone, S; Aristilde, L; Bargar, J; Klein, AR; Cliff, JBX-ray methods provide unique insight into the biogeochemical cycling of nutrients, such as C, P and Ca, in the subsurface, particularly when nutrient availability is mediated by interactions with the solid phase. For instance, mineral phases in the sediments may sorb nutrients, mediating their availability to microbes. In other instances, minerals can catalyze nutrient transformations. In this talk, I will give two examples of how soft and tender X-ray spectroscopies can be utilized to examine critical steps in nutrient cycling. In the first example, Ca speciation in the subsurface is investigated using a combination of scanning transmission X-ray microscopy (STXM) and tender X-ray microprobe analysis. Soils and sediments host large stores of organic carbon which can be released to the atmosphere upon mineralization. Ca may play a key role in preventing organic matter (OM) mineralization by promoting mineral sorption. Although it has long been recognized that Ca forms cation bridges that link negatively charged organic and mineral functional groups, there is little direct experimental observation of this, which is necessary for a molecular-scale, predictive understanding. We examined whether OM-Ca was co-associated with specific minerals, and with what OM types Ca was associated using nano secondary ion mass spectrometry (NanoSIMS) and STXM. The Ca speciation was probed further using (micro-) X-ray absorption near edge structure (XANES) spectroscopy. In the second example, I will discuss how XANES spectroscopy can be used to elucidate abiotic transformation of organic P to inorganic P, rendering it bioavailable. Organic P species, in particular phosphate esters such as those found in ribonucleotides, can comprise a significant fraction of total P in soils and sediments. P K-edge XANES spectroscopy was utilized to monitor dephosphorylation of ribonucleotides by ferrihydrite, and helped to elucidate how the extent of dephosphorylation was related to organic P type.