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5 results on '"Jonnard P"'

1. Study of Complex Waveguide Structure using Soft X-ray Reflectivity Technique.

Author

Singh, Amol, Modi, Mohammed H., Dhawan, R., Jonnard, P., Le Guen, K., and André, J.-M.

Subjects
WAVEGUIDES, SOFT X rays, REFLECTANCE, GRAZING incidence, LAYER structure (Solids), SUBSTRATES (Materials science)
Abstract

Grazing incidence x-ray reflectivity (GIXRR) technique is commonly used for structural investigation of layered structures. In case of complex x-ray waveguide structure it is difficult to obtain structural parameters using GIXRR technique owing to narrowly spaced Kiessig fringes. We used GIXRR and soft x-ray reflectivity (SXR) technique to study the x-ray waveguide structure composed of 4 layers Al/ZrC/Al/W on a Si substrate. Structural parameters of the stacks, density, thickness and roughness of the layers, are determined through fitting of SXR data. Advantages of SXR over GIXRR for such layered structure are shown. [ABSTRACT FROM AUTHOR]

Published
2017
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2. An etched multilayer as a dispersive element in a curved-crystal spectrometer: implementation and performance.

Author

Jonnard, P., Le Guen, K., André, J.-M., Coudevylle, J.-R., and Isac, N.

Abstract

Etched multilayers obtained by forming a laminar grating pattern within interferential multilayer mirrors are used in the soft X-ray range to improve the spectral resolution of wavelength dispersive spectrometers equipped with periodic multilayers. We describe the fabrication process of such an etched multilayer dispersive element, its characterization through reflectivity measurement and simulations, and its implementation in a high-resolution Johann-type spectrometer. The specially designed patterning of a Mo/B4C multilayer is found fruitful in the range of the C K emission as the diffraction pattern narrows by a factor 4 with respect to the non-etched structure. This dispersive element with an improved spectral resolution was successfully implemented for electronic structure study with an improved spectral resolution by X-ray emission spectroscopy. As first results, we present the distinction between the chemical states of carbon atoms in various compounds, such as graphite, SiC and B4C, by the different shape of their C K emission band. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2012
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3. High Spectral Resolution With Multilayer Gratings.

Author

André, J.-M., Le Guen, K., and Jonnard, P.

Subjects
DIFFRACTION gratings, OPTICAL resolution, MIRRORS, SPECTRUM analysis, PARTICLES (Nuclear physics), DETECTORS
Abstract

The improvement of spectral resolution brought about by the use of multilayer grating (MG) instead of multilayer mirror (MM) is analyzed. The spectrum of a complex sample containing various elements excited under electron irradiation is studied. This sample is a pellet made by pressing powders of Cu and compounds with Fe and F atoms. The MM is a Mo/B4C periodic multilayer with a period of about 6 nm; for the MG a grating of 1 μm period has been etched in the MM. It is shown that the MG can easily resolve the F Kα and Fe Lα emissions, separated by about 30 eV, whereas the MM is unable to give such a performance. A comparison with an EDS (SDD) detector is also given. It is also shown that the MG can improve the detection limit. Finally the role of the slit placed in front of the detector is discussed. [ABSTRACT FROM AUTHOR]

Published
2010
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4. Molybdenum–silicon aperiodic multilayer broadband polarizer for 13–30nm wavelength range

Author

Tan, M.Y., Zhu, J.T., Chen, L.Y., Wang, Z.S., Le Guen, K., Jonnard, P., Giglia, A., Mahne, N., and Nannarone, S.

Subjects
*MOLYBDENUM, *SILICON, *MULTILAYERED thin films, *WAVELENGTHS, *SYNCHROTRON radiation, *POLARIZERS (Light), *STANDARD deviations, *PHYSICS experiments
Abstract

Abstract: Aperiodic molybdenum/silicon (Mo/Si) multilayer designed as a broadband polarizer with reflectivity over a wide wavelength range of 13–30nm at a fixed incidence angle of 45° was developed by a numerical method. The multilayer was prepared using direct current magnetron sputtering. The reflectivity and polarizing properties were characterized using synchrotron radiation. In 13–30nm wavelength region, the measured s-reflectivity (R s ) with standard deviation is 13.5%±3.1%, p-reflectivity (R p ) with standard deviation is 1.4%±0.5%. The mean of polarization degree is 81.2%. This broadband multilayer polarizer can be used in extreme ultraviolet polarization measurements, and will greatly simplify experimental arrangements. [Copyright &y& Elsevier]

Published
2011
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5. Determination of the magnetization profile of Co/Mg periodic multilayers by magneto-optic Kerr effect and X-ray magnetic resonant reflectivity

Author

P Jonnard1, K Le Guen1, J-M André1, R Delaunay1, N Mahne2, A Giglia2, S Nannarone2, 3, A Verna2, Z-S Wang4, J-T Zhu4, S-K Zhou4, Laboratoire de Chimie Physique - Matière et Rayonnement ( LCPMR ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Centre National de la Recherche Scientifique ( CNRS ), CNR - Istituto Officina dei Materiali ( IOM ), Consiglio Nazionale delle Ricerche [Roma] ( CNR ), Laboratorio Nazionale TASC ( TASC ), Consiglio Nazionale delle Ricerche ( CNR ), Institute of Precision Optical Engineering. ( IPOE ), Tongji University, Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), CNR Istituto Officina dei Materiali (IOM), Consiglio Nazionale delle Ricerche [Roma] (CNR), Laboratorio Nazionale TASC (TASC), Consiglio Nazionale delle Ricerche (CNR), Institute of Precision Optical Engineering [Shangai] (IPOE), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), AA. VV., Jonnard, P., Le Guen, K., André, J. M., Delaunay, R., Mahne, N., Giglia, A., Nannarone, S., Verna, Adriano, Wang, Z. S., Zhu, J. T., and Zhou, S. K.

Subjects
History, Materials science, FOS: Physical sciences, Bragg peak, 02 engineering and technology, magnesium, Dichroic glass, 01 natural sciences, Signal, Education, 010309 optics, Magnetization, X-ray magnetic resonant reflectivity, 0103 physical sciences, magneto-optic Kerr effect, Condensed Matter - Materials Science, Condensed matter physics, multilayer, X-ray, Materials Science (cond-mat.mtrl-sci), [ PHYS.COND.CM-GEN ] Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 021001 nanoscience & nanotechnology, cobalt, Computer Science Applications, Magnetic field, Absorption edge, Magneto-optic Kerr effect, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0210 nano-technology
Abstract

The resonant magnetic reflectivity of Co/Mg multilayers around the Co L2,3 absorption edge is simulated then measured on a specifically designed sample. The dichroic signal is obtained when making the difference between the two reflectivities measured with the magnetic field applied in two opposite directions parallel to the sample surface. The simulations show that the existence of magnetic dead layers at the interfaces between the Co and Mg layers leads to an important increase of the dichroic signal measured in the vicinity of the third Bragg peak that otherwise should be negligible. The measurements are in agreement with the model introducing 0.25 nm thick dead layers. This is attributed to the Co atoms in contact with the Mg layers and thus we conclude that the Co-Mg interfaces are abrupt from the magnetic point of view., 8 pages

Published
2013
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