P. Melpignano

Sincrotrone Trieste S.C.p.A., Trst, Friuli Venezia Giulia, Italy

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Publications (6)8.92 Total impact

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    ABSTRACT: The article describes the ESCA microscopy beamline dedicated to high spatial resolution quantitative and qualitative analysis on surfaces and interfaces. The scanning microscope is constructed to work both in transmission and photoemission within the photon energy range from 200 to 1200 eV with a spatial resolution of ∼0.1 μm. A Fresnel zone plate demagnifies the photon beam to submicrometer dimensions with 10<sup>9</sup>–10<sup>10</sup> photons/s in the focus spot. A photodiode and a hemispherical electron energy analyzer are used as detectors for recording the transmitted x‐rays and emitted photoelectrons, respectively. The operation modes in photoemission give the opportunity to obtain conventional energy distribution curve spectra from a microspot or a two‐dimensional micrograph of the spatial distribution and local concentration of a selected element as the sample is mechanically scanned. For conductive specimen topography measurements of a selected surface area probed by SPEM are possible using a scanning tunnelling microscope. The first test images of a zone plate and an e‐beam written specimen with 1 μm<sup>2</sup> Au squares on Si have shown a spatial resolution better than 0.2 μm. © 1995 American Institute of Physics.
    No preview · Article · Nov 1995 · Review of Scientific Instruments
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    ABSTRACT: The Super‐ESCA beamline has been designed for high resolution core level spectroscopy of adsorbates on single crystal surfaces using soft x‐ray synchrotron radiation. It receives the light from an 81 period undulator with 5.6 cm period and 4.5 m length in the storage ring ELETTRA. The tunability of this insertion device, at a storage ring electron energy of 2.0 GeV and the connected modified SX700 monochromator allows the performance of experiments at this beamline in the photon energy range 100–2000 eV. This beamline is now operational and first absorption spectra are presented which show available resolving powers varying from 8000 to 3000 for photon energies between 240 and 850 eV. © 1995 American Institute of Physics.
    Full-text · Article · Mar 1995 · Review of Scientific Instruments
  • P. Melpignano · S. Di Fonzo · A. Bianco · W. Jark
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    ABSTRACT: The concept of variation of the angle of deflection in a spherical grating monochromator allows to keep the defocus aberration at zero while keeping the entrance and the exit slit distances fixed. This report presents the optimization of this concept for different applications in which one would always like to work with maximum resolving power and photon flux while keeping the exit slit at a fixed position. Three designs are presented for medium resolution (E/ΔE = 3000) soft x‐ray microscopy studies in the photon energy range 200–1200 eV and 20–300 eV and for high‐resolution spectroscopy (E/ΔE≳10 000) in the larger range 20–800 eV. © 1995 American Institute of Physics.
    No preview · Article · Mar 1995 · Review of Scientific Instruments
  • Werner Jark · Patrizia Melpignano
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    ABSTRACT: This report describes the optimisation of a spherical grating monochromator operated with variable included angle as proposed by Padmore for microscopy experiments utilizing soft X-ray synchrotron radiation. The projected working range is for photon energies between 200 eV and above 1000 eV. The resolving powers requested for zone-plate microscopy are of the order of 3000. This will be achieved in a monochromator exit slit of 30 μm, which is just the ideal source size for the following zone-plate. Further optimisations of the resolution and the tuning range for more general use are discussed.
    No preview · Article · Sep 1994 · Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
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    ABSTRACT: This report presents the project for the development of a combined facility consisting of a high spatial resolution soft x-ray scanning photoelectron microscope (SPEM) and a scanning tunnelling microscope (STM) that is going to be built in an ultrahigh vacuum (UHV) station on one of the undulator beam lines at ELETTRA, Trieste. The photon microprobe for SPEM will be generated using a zone plate diffraction optic. A special design of a spherical grating monochromator will provide the source for illuminating the zone plate. The emitted photoelectrons will be detected and analysed using a high-energy resolution hemispherical analyser with a large acceptance angle. The performance of the SPEM is projected to be as follows: (1) a photon spot size on the sample of ∼50 × 50 nm2;(2) a tunable photon energy range of 200–800 eV, with an energy resolving power of 3000 at the carbon K-edge;(3) a photon flux in the spot that is > 109 photons s−1 (0.1% body wt.)−1.The projected performance of the STM instrument ensures a lateral resolution better than 2 Å. The combination of SPEM and STM techniques will enable chemical and structural mapping within the same microscopic areas of the sample surface. Descriptions of the main beam line components together with some examples of possible applications of this unique tool are included in the paper.
    No preview · Article · Sep 1992 · Surface and Interface Analysis
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    F. Zanini · S. Di Fonzo · P. Melpignano · W. Jark
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    ABSTRACT: A possible design for a spherical grating monochromator is based on the translation of the entrance slit in order to minimize the system aberrations during the wavelength scan. This configuration has been studied both analytically and by means of extended ray‐tracing calculations and the design and performance of such a monochromator are discussed. In order to verify advantages and limitations of this solution a systematic comparison with a spherical grating monochromator with a moveable exit slit has been performed.
    Full-text · Article · Feb 1992 · Review of Scientific Instruments