Papers by Emmanuel Pantos
Journal of Physics D: Applied Physics, 2004
The first comprehensive survey of band-edge features in the ternary group of naturally occurring ... more The first comprehensive survey of band-edge features in the ternary group of naturally occurring aluminosilicates (the feldspars) is presented. Synchrotron-based luminescence excitation of KAlSi 3 O 8, NaAlSi 3 O 8 and CaAl 2 Si 2 O 8 allows the measurement of the ...
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Il Nuovo Cimento C, 2007
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Archaeological copper artefacts recovered from wet saline environments are often stored in tap wa... more Archaeological copper artefacts recovered from wet saline environments are often stored in tap water and stabilized in sodium sesquicarbonate solutions. Modification of the natural patina and development of active corrosion can occur during these processes. This implies that monitoring of storage/stabilisation processes is necessary. The focus of the study consists of examining how corrosion potential (Ecorr) measurements can contribute in providing information on the effectiveness of storage and stabilisation treatments. This paper reports on the Ecorr versus time plots of artificially prepared copper coupons (covered or not with corrosion layers) immersed in tap water and a sodium sesquicarbonate solution. Synchrotron radiation XRD was performed in parallel to understand the reactions that take place during the immersion processes. .
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Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2004
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Journal of Synchrotron Radiation, 2002
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Journal of Physics D: Applied Physics, 2011
The luminescence properties of Fe3+ defects in feldspar are well know, but the role played by Fe2... more The luminescence properties of Fe3+ defects in feldspar are well know, but the role played by Fe2+ centres remains ambiguous, with tentative previous evidence suggesting it could act as a luminescence activator, luminescence quencher, or neither one nor the other: the outcome of these arguments would be of direct and topical relevance to consideration of using Fe3+ luminescence for the in situ dating of Martian sediments in future probe missions to the planet. Therefore, to elucidate the relative roles of Fe2+ and Fe3+, a synchrotron radiation study of Fe2+/Fe3+ defects in feldspar has been undertaken by probing the L-edges of the ion. Partial electron yield results allow a measure of the relative proportion of the ion states to be made, but of itself provides no indication of the defect's optical activity: in order to determine the latter, optical detection of x-ray absorption spectroscopy has been deployed. Although minor differences in the Fe2+/Fe3+ ratios are established usi...
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Journal of Molecular Spectroscopy, 1978
ABSTRACT Extinction coefficient spectra and oscillator strength values for the benzene transition... more ABSTRACT Extinction coefficient spectra and oscillator strength values for the benzene transitions in the 4.6 to 9.2 eV region have been measured taking into account the effect of the instrumental bandwidth. By normalizing Koch and Otto's (1) uncalibrated absorption spectrum at 6 to 36 eV with our spectrum recorded with the same bandpass we provide values of ϵ in the region 4.6 to 36 eV. The dependence of ϵmax on the bandpass is presented and a comparison is made between theoretical band intensities in a progression and band intensities measured experimentally. A total integrated intensity of 0.075 is found for the Rydberg transitions below the first I.P. and a total value of 17.5 is found for the whole region 4.6 to 36 eV.
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Chemical Physics Letters, 1981
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EuroPhysicsNews, 2007
1 Department of Chemistry, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1 2610 ... more 1 Department of Chemistry, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1 2610 Antwerp Belgium 2 CCLRC, Daresbury Laboratory Warrington UK WA4 4AD 3 Department of Analytical Chemistry, Ghent University, Krijgslaan 281-S12 9000 Ghent Belgium, ...
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tion of reactive groups on the surface of the particles is During the preparation of silica by ac... more tion of reactive groups on the surface of the particles is During the preparation of silica by acidi®cation of water glass, stochastic, directions of particle–particle bonds are rather primary silica particles form extended and rami®ed aggregates. arbitrary and therefore particle–particle interactions result The growing aggregates form a gel, a tenuous network of intercon- in tenuous aggregates with an amorphous structure. Interac-nected aggregates. After aging and drying of the wet gel, porous tions are not restricted to particle–particle or particle–aggre-silica is obtained. To study the extremely vulnerable aggregates gate bonds, and interactions between aggregates or clustersonly noninvasive methods are allowed. Moreover, because of the of particles are also possible, leading to highly ramified andcolloidal scale many methods based on (atomic or molecular scale) extended aggregates.spectroscopy are not informative. Scanning transmission x-ray mi-Polymerization or particle format...
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Journal De Physique Iv, 1994
Four computer algorithms of relevance to Synchrotron Radiation research have been implemented for... more Four computer algorithms of relevance to Synchrotron Radiation research have been implemented for parallel execution using the Parallel Virtual Machine (PVM) software harness. In all four cases the Single Program Multiple Data (SPMD) approach has been used resulting in a computationally simple but very effective implementation where processing time is inversely proportional to the number of computing elements used
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Review of Scientific Instruments, 1992
Since the early work of Huxley and collaborators [H. E. Huxley, A. R. Faruqui, J. Bordas, M. H. J... more Since the early work of Huxley and collaborators [H. E. Huxley, A. R. Faruqui, J. Bordas, M. H. J. Koch, and J. R. Milch, Nature 284, 5752, 140 (1980)], time‐resolved x‐ray diffraction using synchrotron radiation has provided and continues to provide unique information on the structural dynamics of muscle, thus addressing the fundamental question of how chemical energy is transformed into motion. While considerable progress has been made in improving data collection procedures, relatively little progress has taken place in the development of computational methods with which to interpret the large amounts of structural and functional information contained in the experimental data. Given the characteristics of the structure of muscle this poses a considerable computational challenge since realistic models of the molecular components making up the muscle fibres require extensive algorithms and computational resources. We present here a progress report on our work on this topic and describe some of the algorithmic aspects of muscle modeling as a dynamic structure and we show how visualization techniques are used to check the effect of different factors. We also describe briefly some of the insights we have gained from the modeling procedures and ‘‘theoretical experiments,’’ and the current model that fits qualitatively the main features in the experimental pattern.Since the early work of Huxley and collaborators [H. E. Huxley, A. R. Faruqui, J. Bordas, M. H. J. Koch, and J. R. Milch, Nature 284, 5752, 140 (1980)], time‐resolved x‐ray diffraction using synchrotron radiation has provided and continues to provide unique information on the structural dynamics of muscle, thus addressing the fundamental question of how chemical energy is transformed into motion. While considerable progress has been made in improving data collection procedures, relatively little progress has taken place in the development of computational methods with which to interpret the large amounts of structural and functional information contained in the experimental data. Given the characteristics of the structure of muscle this poses a considerable computational challenge since realistic models of the molecular components making up the muscle fibres require extensive algorithms and computational resources. We present here a progress report on our work on this topic and describe some of the algori...
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ABSTRACT The famous Dead Sea scrolls, found in 1947 at Qumran, point to a group of people, the “E... more ABSTRACT The famous Dead Sea scrolls, found in 1947 at Qumran, point to a group of people, the “Essenes”, described by Pliny, Flavius Josephus and Philo. A large number, recently estimated to be around 950 biblical, sectarian and apocryphal manuscripts have been associated with the Essenes. In 1998, interdisciplinary laboratory research started in Jerusalem between material scientists, museum curators and archaeologists to obtain fresh information of what the manuscripts and the material culture may demonstrate, and how to preserve this cultural heritage for the centuries to come. In 2001, Gunneweg became one of the two members of COST-G8, representing Israel. This opened a golden opportunity to contact various scientists in Europe. The Qumran project of the Hebrew University is a collaborative endeavour between 17 institutions applying Neutron Activation Analysis, Petrography, Thermoluminescence, Magnetic Susceptibility, Optical and Electron Microscopy, Synchrotron X-Ray Diffraction and Fluorescence, High Performance Liquid Chromatography, Raman Spectroscopy, Carbon 14 dating and DNA analysis of the scroll parchment.
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Nuovo Cimento della Societa Italiana di Fisica C, 2007
ABSTRACT From ancient times to today glasses, generally based on siliceous oxides cooled to a har... more ABSTRACT From ancient times to today glasses, generally based on siliceous oxides cooled to a hard condition to avoid crystallization, have been extensively used, for their chemical-physical durability. Indeed, glass is one of the materials most frequently discovered during archaeological excavations. The degradation induces the loss of brightness and transparency, and the formation of pits, crystals and patinas. Sometimes peeling layers may appear, too. All these phenomena alter irreversibly the aesthetic appearance of the glassworks. The research in this field, initially focused on the knowledge of history, composition and technology of the manufacture of works of art is trying now to rationalize the problems connected with degradation processes through, both, very sensitive characterization techniques and model experiments simulating degradation phenomena. In this work we deepen the analyses of glass degradation regarding samples coming from the Roman ship Iulia Felix found on the seabed of Grado lagoon (Italy) and dated to the 11 century A.D. Their surfaces have been investigated through XPS (X-Ray Photoelectron Spectroscopy) and SIMS (Secondary Ion Mass Spectrometry) to understand water effects on glass degradation and interesting considerations oil the mobility of the present ionic species are proposed. We also report the results of micro-XRF and synchrotron-XRD analyses that will allow us to single out the various crystallization species present resulting from the degradation phenomena of these glasses.
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The Analyst, 2003
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Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1995
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Journal of Archaeological Science, 2001
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Journal of Applied Crystallography, 1996
ABSTRACT The application limit of the MULTX program for predicting Renninger-scanning X-ray multi... more ABSTRACT The application limit of the MULTX program for predicting Renninger-scanning X-ray multiple diffraction data is extended in order to simulate Renninger scans for semiconductor single-crystal and heteroepitaxial structures recorded using synchrotron radiation. The experimental synchrotron-radiation Renninger scan for InP(006) bulk material is taken as the standard to analyse the effects of both the polarization factor and diffracted-beam path length. The polarization of the synchrotron-radiation beam is considered using a matrix approach. The diffracted-beam path length involved in the surface secondary beam cases is analysed taking into account the dynamical theory for perfect crystals and the kinematical theory as the limit of the dynamical case for thin crystals. Renninger scans of AlGaInAs quaternary layer structures, simulated with the MULTX program, show a very good agreement (R = 0.085) with the corresponding experimental data.
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Chemical Physics Letters, 1977
Abstract Solid neon doped by xenon and benzene exhibits xenon absorption and benzene luminescence... more Abstract Solid neon doped by xenon and benzene exhibits xenon absorption and benzene luminescence for excitation in the range 8.2 cV hv 5 5d xenon impurity state.
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Papers by Emmanuel Pantos