Browsing by Author "Balaur, E"

Now showing 1 - 4 of 4
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    An iterative method for near-field Fresnel region polychromatic phase contrast imaging
    (IOP Publishing, 2017-07-01) Carroll, AJ; van Riessen, GA; Balaur, E; Dolbnya, IP; Tran, GN; Peele, AG
    We present an iterative method for polychromatic phase contrast imaging that is suitable for broadband illumination and which allows for the quantitative determination of the thickness of an object given the refractive index of the sample material. Experimental and simulation results suggest the iterative method provides comparable image quality and quantitative object thickness determination when compared to the analytical polychromatic transport of intensity and contrast transfer function methods. The ability of the iterative method to work over a wider range of experimental conditions means the iterative method is a suitable candidate for use with polychromatic illumination and may deliver more utility for laboratory-based x-ray sources, which typically have a broad spectrum. © The Authors 2017 published by IOP Publishing Ltd. Open Access CC 3.0
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    Measurements of long-range electronic correlations during femtosecond diffraction experiments performed on nanocrystals of Buckminsterfullerene
    (MyJove, 2017-08-22) Ryan, RA; Williams, S; Martin, AV; Dilanian, RA; Darmanin, C; Putkunz, CT; Wood, D; Streltsov, VA; Jones, MWM; Gaffney, N; Hofmann, F; Williams, GJ; Boutet, S; Messerschmidt, M; Seibert, M M; Curwood, EK; Balaur, E; Peele, AG; Nugent, KA; Quiney, HM; Abbey, B
    The precise details of the interaction of intense X-ray pulses with matter are a topic of intense interest to researchers attempting to interpret the results of femtosecond X-ray free electron laser (XFEL) experiments. An increasing number of experimental observations have shown that although nuclear motion can be negligible, given a short enough incident pulse duration, electronic motion cannot be ignored. The current and widely accepted models assume that although electrons undergo dynamics driven by interaction with the pulse, their motion could largely be considered 'random'. This would then allow the supposedly incoherent contribution from the electronic motion to be treated as a continuous background signal and thus ignored. The original aim of our experiment was to precisely measure the change in intensity of individual Bragg peaks, due to X-ray induced electronic damage in a model system, crystalline C60. Contrary to this expectation, we observed that at the highest X-ray intensities, the electron dynamics in C60 were in fact highly correlated, and over sufficiently long distances that the positions of the Bragg reflections are significantly altered. This paper describes in detail the methods and protocols used for these experiments, which were conducted both at the Linac Coherent Light Source (LCLS) and the Australian Synchrotron (AS) as well as the crystallographic approaches used to analyse the data. © 2017 Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported. .
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    Propagation-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, AG
    Through 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
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    Simultaneous 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, ST
    A 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.