“Accurate evaluation of \mu-PIXE and \mu-XRF spectral data through iterative least squares fitting”. Janssens K, Vekemans B, Adams F, van Espen P, Mutsaers P, Nuclear instruments and methods in physics research: B: beam interactions with materials and atoms
T2 –, 7th International Conference on Particle Induced X-ray Emission and Its Analytical Applications, MAY 26-30, 1995, Abano Terme, Italy 109, 179 (1996). http://doi.org/10.1016/0168-583X(95)01211-7
Abstract: The integration of the nonlinear least squares X-ray spectrum evaluation progam AXIL. into a mu-PIXE and a mu-XRF setup is discussed. The use of the software when procesing data sets derived from biological and geological samples is described.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
DOI: 10.1016/0168-583X(95)01211-7
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“Possibilities of energy-resolved X-ray radiography for the investigation of paintings”. Cabal Rodríguez AE, Leyva Pernia D, Schalm O, van Espen PJM, Analytical and bioanalytical chemistry 402, 1471 (2012). http://doi.org/10.1007/S00216-011-5230-X
Abstract: X-ray radiographic images of paintings often show little or no contrast. In order to increase the contrast in radiographic images we measured the X-ray spectrum of a low power X-ray tube, after passing through the painting, with a high energy-resolution SDD detector. To obtain images, the detector is collimated with a 400 mu m diameter pinhole and the painting was moved through the beam in the x and y-direction using a dwell time of a few seconds per pixel. The data obtained consists of a data cube of, typically, 200 x 200 pixels and a 512-channel X-ray spectrum for each pixel, spanning the energy range from 0 to 40 keV. Having the absorbance spectrum available for each pixel, we are able, a posteriori, to produce images by edge subtraction for any given element. In this way high contrast, element-specific, images can be obtained. Because of the high energy-resolution a much simpler edge subtraction algorithm can be applied. We also used principal-component imaging to obtain, in a more automated way, images with high contrast. Some of these images can easily be attributed to specific elements. It turns out that preprocessing of the spectral data is crucial for the success of the multivariate image processing.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1007/S00216-011-5230-X
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“Study of dpa distributions in electron irradiated YBCO slabs through MCCM algorithm”. Piñera I, Cruz CM, van Espen P, Abreu Y, Leyva A, Nuclear instruments and methods in physics research: B: beam interactions with materials and atoms 274, 191 (2012). http://doi.org/10.1016/J.NIMB.2011.11.021
Abstract: The Monte Carlo assisted Classical Method (MCCM) consists on a calculation procedure for determining the displacements per atom (dpa) distribution in solid materials. This algorithm allows studying the gamma and electron irradiation damage in different materials. It is based on the electrons elastic scattering classic theories and the use of Monte Carlo simulation for the physical processes involved. The present study deals with the Monte Carlo simulation of electron irradiation effects on YBa2Cu3O7-x (YBCO) slabs using the MCNPX code system. Displacements per atom distributions are obtained through the MCCM for electron irradiation up to 10 MeV. In-depth dpa profiles for electrons and positrons are obtained and analysed. Also, dpa contributions from each atomic specie in the material are calculated. It was found that the dpa distribution is more homogeneous in the material volume when increasing energy of incident electrons. Also, the dpa produced by positrons has no relevance when irradiating with electrons, in contrast with previous similar gamma irradiation studies. All the results are presented and discussed in this contribution. (C) 2011 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.NIMB.2011.11.021
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“Electric field gradient calculations in ZnO samples implanted with 111In(111Cd)”. Abreu Y, Cruz CM, van Espen P, Pérez C, Piñera I, Leyva A, Cabal AE, Solid state communications 152, 399 (2012). http://doi.org/10.1016/J.SSC.2011.12.001
Abstract: A first-principles study of the electric field gradient (EFG) calculated for ideal and In-111(Cd-111) implanted ZnO samples is reported in the present work. The study was made for ZnO ideal hexagonal structures and supercells were introduced in order to consider the possible implantation environments. The calculation was done using the “WIEN2k” code within the density functional theory, the exchange and correlation effects were determined by the GGA approximation. Three possible In-111(Cd-111) implantation configurations were studied, one substitutional incorporation at cation site and two interstitials. The obtained EFG values for the ideal structure and the substitutional site are in good agreement with the experimental reports measured by perturbed angular correlation (PAC) and high precision nuclear magnetic resonance (NMR). Thus, the ascription of substitutional incorporation of In-111(Cd-111) probe atom at the ZnO cation site after annealing was confirmed. (C) 2011 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
DOI: 10.1016/J.SSC.2011.12.001
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Gijbels R, van Grieken R, Blommaert W, Van 't dack L, van Espen P, Nullens H, Saelens R (1983) Application of analytical methods for trace elements in geothermal waters : part 2 : Plombières, Bains-les-Bains, Bourbonne (Vosges). S.l
Keywords: MA3 Book as author; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
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“Study of quasi-fractal many-particle-systems and percolation networks by zero-loss spectroscopic imaging, electron energy-loss spectroscopy and digital image analysis”. Oleshko V, Kindratenko V, Gijbels R, van Espen P, Jacob W, Mikrochimica acta: supplementum 13, 443 (1996)
Abstract: Submicron colloidal Ag particles and nano-sized filaments forming a statistical percolation network during ''in situ'' development of double structure tabular microcrystals of AgRr(I) emulsions have been studied by electron energy-loss spectroscopy and zero-loss electron spectroscopic imaging (EELS/ZLESI). Image analysis has shown that random quasi-fractal clusters were formed in the colloid. ZLESI has been applied to characterise the morphology and defect structure of aggregated particles and filaments. Their energy-loss spectra revealed plasmon excitations and interband 4d electron transitions between 4-32 eV energy-loss. To study the cluster structure and its relation to the physical properties, fractal analysis including estimations of cluster fractal dimensions and of density autocorrelation functions has been performed. Mechanisms of fractal aggregation based on known models of diffusion limited aggregation, cluster-cluster aggregation and percolation are discussed.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Chemometrics (Mitac 3)
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“Three-dimensional chemical characterization of complex silver halide microcrystals by scanning ion microprobe mass analysis”. Verlinden G, Janssens G, Gijbels R, van Espen P, Geuens I, Analytical chemistry 69, 3773 (1997). http://doi.org/10.1021/ac970010r
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Chemometrics (Mitac 3)
Impact Factor: 6.32
Times cited: 6
DOI: 10.1021/ac970010r
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“Automated particle analysis of populations of silver halide microcrystals by electron probe microanalysis under cryogenic conditions”. Gregory CL, Nullens HA, Gijbels RH, van Espen PJ, Geuens I, de Keyzer R, Analytical chemistry 70, 2551 (1998). http://doi.org/10.1021/ac9710644
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Chemometrics (Mitac 3)
Impact Factor: 6.32
Times cited: 12
DOI: 10.1021/ac9710644
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“Quantitative surface analysis of silver halide microcrystals using scanning ion microprobe and scanning Auger microprobe”. Janssens G, Geuens I, de Keyzer R, van Espen P, Gijbels R, Hubin A, Terryn H, Vereecken J Wiley, Chichester, page 161 (1996).
Keywords: H3 Book chapter; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Chemometrics (Mitac 3)
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“A new electrostatic transfer line for improved transmission in Fourier transform laser microprobe mass spectrometry with external ion source”. van Vaeck L, van Espen P, Gijbels R, Baykut G, Laukien FH, European mass spectrometry 6, 277 (2000). http://doi.org/10.1255/ejms.342
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Chemometrics (Mitac 3)
Times cited: 10
DOI: 10.1255/ejms.342
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“The primary energy dependence of backscattered electron images up to 100 keV”. Geuens I, Nys B, Naudts J, Gijbels R, Jacob W, van Espen P, Scanning microscopy 5, 339 (1991)
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Chemometrics (Mitac 3)
Times cited: 3
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