Fernando Scarinci - Academia.edu (original) (raw)

Papers by Fernando Scarinci

Research paper thumbnail of Analysis of tapered front-coupling X-ray waveguides

Journal of Synchrotron Radiation, 2010

The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with v... more The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with vacuum gap and Si claddings are analyzed in detail, starting from the source and ending at the detector. The general case of linearly tapered WGs (i.e. with the entrance aperture different from the exit one) is considered. Different kinds of sources, i.e. synchrotron radiation and laboratory desk-top sources, have been considered, with the former providing a fully coherent incoming beam and the latter partially coherent beams. It is demonstrated that useful information about the parameters of the WG can be derived, comparing experimental results with computer simulation based on analytical solutions of the Helmholtz equation which take into account the amplitude and phase matching between the standing waves created in front of the WG, and the resonance modes propagating into the WG.

Research paper thumbnail of Analysis of tapered front-coupling X-ray waveguides

Journal of Synchrotron Radiation, 2010

The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with v... more The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with vacuum gap and Si claddings are analyzed in detail, starting from the source and ending at the detector. The general case of linearly tapered WGs (i.e. with the entrance aperture different from the exit one) is considered. Different kinds of sources, i.e. synchrotron radiation and laboratory desk-top sources, have been considered, with the former providing a fully coherent incoming beam and the latter partially coherent beams. It is demonstrated that useful information about the parameters of the WG can be derived, comparing experimental results with computer simulation based on analytical solutions of the Helmholtz equation which take into account the amplitude and phase matching between the standing waves created in front of the WG, and the resonance modes propagating into the WG.

Research paper thumbnail of Rb adsorption on the Si(001)2×1 surface: An x-ray-standing-waves study

Physical Review B, 1995

The Rb adsorption site distribution on the Si(001)2×1 surface and the alkali-metal Si bond length... more The Rb adsorption site distribution on the Si(001)2×1 surface and the alkali-metal Si bond length have been determined for low (0.19+/-0.02 ML) alkali-metal coverages using the x-ray-standing-wave fields generated by (004), (113), and (022) bulk-diffracting planes. Rb atoms have been found to adsorb preferentially at valley (V) sites and on top of the higher of the Si asymmetric dimers (T1).

Research paper thumbnail of Application of the Borrmann effect to x-ray monochromatization and to the overlayer versus substrate signal-ratio enhancement

Physical Review B, 1992

In x-ray-excited surface spectroscopies one of the most relevant figures of merit is the overlaye... more In x-ray-excited surface spectroscopies one of the most relevant figures of merit is the overlayer versus substrate signal ratio. In this work we propose to utilize the Borrmann (or anomalous-transmission) effect, which takes place in perfect crystals, in order to have a weaker interaction of the incident beam with the substrate. In this way the overlayer versus substrate signal ratio

Research paper thumbnail of Nature of the band gap of polycrystalline β-FeSi 2 films

We present experimental evidence for the indirect nature of the beta-FeSi2 gap. We furthermore sh... more We present experimental evidence for the indirect nature of the beta-FeSi2 gap. We furthermore show, by analyzing the temperature dependence of the direct gap by means of a thermodynamic empirical model, that beta-FeSi2 exhibits an unusually strong electron-phonon interaction. We finally deduce the electron-hole mobility from our measurements.

Research paper thumbnail of Structural study of the Si–alkali-metal interface with x-ray standing waves

Physical Review B, 1992

... Roma, Italy E. Fontes and JR Patel AT&T Bell Laboratories, Murray Hill, New J... more ... Roma, Italy E. Fontes and JR Patel AT&T Bell Laboratories, Murray Hill, New Jersey 07974 (Received 20 December 1991; revised manuscript received 29 June 1992) X-ray standing-wave measurements on Cs and Rb adlayers on the Si( 111)7 X 7 surface are presented. ...

Research paper thumbnail of Advancements in X-ray waveguides and their applications in coherent diffraction imaging

Radiation Physics and Chemistry, 2009

a b s t r a c t X-ray planar waveguides are currently used tools, in synchrotron radiation facili... more a b s t r a c t X-ray planar waveguides are currently used tools, in synchrotron radiation facilities, to produce a coherent beam with typical dimensions in the range of tens or hundreds of nanometers. The properties of waveguided beams such as divergence and coherence turns out to be very interesting for several applications both in synchrotron and in laboratory sources. These features will be reviewed in the present paper for different coupling methods of the radiation field with the waveguide channel. Details of fabrication procedures and experimental results concerning front coupling waveguide are reported. The waveguide properties can be estimated from the far-field diffracted beam by a Fourier analysis giving the autocorrelation function of the exit field. Due to the high degree of coherence of the exiting beam, X-ray waveguides can be successfully exploited in coherent diffraction imaging experiments. We review results concerning Fresnel coherent diffraction imaging experiments with hard X-rays, using planar waveguides as optical elements in one and two dimensions.

Research paper thumbnail of An automatic analysis of strain-depth profile in X-ray microdiffraction

Physica B: Condensed Matter, 2004

... The waveguide has been developed in collaboration with Werner Jark and SilviaDi Fonzo from El... more ... The waveguide has been developed in collaboration with Werner Jark and SilviaDi Fonzo from Elettra-Sincrotrone Trieste (IT). The authors thank the ID32 staff of ESRF for the very helpful collaboration during the experiment. ...

Research paper thumbnail of X-ray phase contrast microscopy at 300 nm resolution with laboratory sources

Optics Express, 2010

We report the performance of an X-ray phase contrast microscope for laboratory sources with 300 n... more We report the performance of an X-ray phase contrast microscope for laboratory sources with 300 nm spatial resolution. The microscope is based on a commercial X-ray microfocus source equipped with a planar X-ray waveguide able to produce a sub-micrometer x-ray beam in one dimension. Phase contrast images of representative samples are reported. The achieved contrast and resolution is discussed for different configurations. The proposed approach could represent a simple, inexpensive, solution for sub-micrometer resolution imaging with small laboratory setups.

Research paper thumbnail of Analysis of tapered front-coupling X-ray waveguides

Journal of Synchrotron Radiation, 2010

The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with v... more The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with vacuum gap and Si claddings are analyzed in detail, starting from the source and ending at the detector. The general case of linearly tapered WGs (i.e. with the entrance aperture different from the exit one) is considered. Different kinds of sources, i.e. synchrotron radiation and laboratory desk-top sources, have been considered, with the former providing a fully coherent incoming beam and the latter partially coherent beams. It is demonstrated that useful information about the parameters of the WG can be derived, comparing experimental results with computer simulation based on analytical solutions of the Helmholtz equation which take into account the amplitude and phase matching between the standing waves created in front of the WG, and the resonance modes propagating into the WG.

Research paper thumbnail of Periodically structured X-ray waveguides

Journal of Synchrotron Radiation, 2013

Author(s) of this paper may load this reprint on their own web site or institutional repository p... more Author(s) of this paper may load this reprint on their own web site or institutional repository provided that this cover page is retained. Republication of this article or its storage in electronic databases other than as specified above is not permitted without prior permission in writing from the IUCr.

Research paper thumbnail of Multisite occupancy at the alkali/silicon (111) interface studied with XSW

Journal of Physics D: Applied Physics, 1993

In this paper the authors report the results of an X-ray standing wave (XSW) study of an Si(111) ... more In this paper the authors report the results of an X-ray standing wave (XSW) study of an Si(111) 7*7-alkali metal (Cs,Rb) interface as a function of coverage. The three-fold hollow (H3) site, the three-fold filled (T4) site and all the dangling bond sites (atop, adatoms and vacancy) have been considered as available sites at the Si surface for the adsorbate.

Research paper thumbnail of X-ray waveguides for laboratory sources

Journal of Physics D: Applied Physics, 2005

A planar x-ray waveguide (WG) consisting of a diamond-like carbon layer sandwiched between two Ni... more A planar x-ray waveguide (WG) consisting of a diamond-like carbon layer sandwiched between two Ni layers is used to demonstrate for the first time the possibility of using WGs as optical elements with standard laboratory sources. The exit beam profile for the first two guided modes has been measured and analysed to demonstrate the high degree of beam coherence. The exit divergence and the beam size are reported and compared with theoretical predictions. Other relevant parameters, such as efficiency and gain, have been measured. This opens up interesting perspectives for the production of nanometre-sized x-ray beams with table-top laboratory sources.

Research paper thumbnail of In situ and ex situ structural characterization of β-FeSi2 films epitaxially grown on Si(111)

Journal of Applied Physics, 1992

The structural properties of β-FeSi2 films grown on Si(111) are studied by means of several techn... more The structural properties of β-FeSi2 films grown on Si(111) are studied by means of several techniques. The films were grown in ultrahigh vacuum by solid phase epitaxy. The as-deposited Fe films were studied in situ by low energy electron diffraction (LEED) and Auger spectroscopy. Fe thicknesses were calibrated by Rutherford backscattering. The behavior of the FeMVV/SiLVV Auger peaks ratio intensity

Research paper thumbnail of X-ray characterization of Si microstructures with high spatial resolution

Journal of Applied Physics, 2004

With the advent of the nanolithographic technologies, the demand of a local strain/stress analysi... more With the advent of the nanolithographic technologies, the demand of a local strain/stress analysis with submicrometer resolution is increasing. In particular, the aim of this work was the study of a patterned Si wafer subjected to preliminary process flow for 0.15 m complementary metal oxide semiconductor generation. The main purpose was to follow the production of strain induced in the Si substrate during the shallow trench isolation process and subsequent formation of active stripes. The determination of structural parameters with very high spatial resolution in one dimension ͑300 nm͒ has been obtained using a scanning x-ray microscope whose main element is a waveguide for medium and high energy x-rays ͑8 -30 keV͒. The experiment, which takes advantage of a nondispersive geometry, required neither a two-dimensional highly sensitive detector nor an insertion device beamline, but it has been carried out on bending magnet beamlines with relatively low flux.

Research paper thumbnail of Computer simulations and experimental results on air-gap X-ray waveguides

Spectrochimica Acta Part B: Atomic Spectroscopy, 2007

X-ray Waveguides (WG) are optical elements able to provide nanometer size coherent X-ray beams. B... more X-ray Waveguides (WG) are optical elements able to provide nanometer size coherent X-ray beams. Both Resonant beam Coupling (RBC) and Front Coupling (FC) can be implemented to couple the incident radiation with the WG. In this paper we implemented a computer code based on finite difference scheme solutions of parabolic wave equations to simulate the coupling and the propagation of electromagnetic waves into air-gap waveguides in Front Coupling mode. Both a synchrotron source and a table-top laboratory sources have been considered. In this last case the degree of coherence of the incoming beam has been explicitly taken into consideration. Air-gap WGs have been fabricated following simple procedures, and tested at the Elettra synchrotron source. The results are in good agreement with theoretical expectations.

Research paper thumbnail of Analysis of tapered front-coupling X-ray waveguides

Journal of Synchrotron Radiation, 2010

The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with v... more The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with vacuum gap and Si claddings are analyzed in detail, starting from the source and ending at the detector. The general case of linearly tapered WGs (i.e. with the entrance aperture different from the exit one) is considered. Different kinds of sources, i.e. synchrotron radiation and laboratory desk-top sources, have been considered, with the former providing a fully coherent incoming beam and the latter partially coherent beams. It is demonstrated that useful information about the parameters of the WG can be derived, comparing experimental results with computer simulation based on analytical solutions of the Helmholtz equation which take into account the amplitude and phase matching between the standing waves created in front of the WG, and the resonance modes propagating into the WG.

Research paper thumbnail of Analysis of tapered front-coupling X-ray waveguides

Journal of Synchrotron Radiation, 2010

The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with v... more The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with vacuum gap and Si claddings are analyzed in detail, starting from the source and ending at the detector. The general case of linearly tapered WGs (i.e. with the entrance aperture different from the exit one) is considered. Different kinds of sources, i.e. synchrotron radiation and laboratory desk-top sources, have been considered, with the former providing a fully coherent incoming beam and the latter partially coherent beams. It is demonstrated that useful information about the parameters of the WG can be derived, comparing experimental results with computer simulation based on analytical solutions of the Helmholtz equation which take into account the amplitude and phase matching between the standing waves created in front of the WG, and the resonance modes propagating into the WG.

Research paper thumbnail of Rb adsorption on the Si(001)2×1 surface: An x-ray-standing-waves study

Physical Review B, 1995

The Rb adsorption site distribution on the Si(001)2×1 surface and the alkali-metal Si bond length... more The Rb adsorption site distribution on the Si(001)2×1 surface and the alkali-metal Si bond length have been determined for low (0.19+/-0.02 ML) alkali-metal coverages using the x-ray-standing-wave fields generated by (004), (113), and (022) bulk-diffracting planes. Rb atoms have been found to adsorb preferentially at valley (V) sites and on top of the higher of the Si asymmetric dimers (T1).

Research paper thumbnail of Application of the Borrmann effect to x-ray monochromatization and to the overlayer versus substrate signal-ratio enhancement

Physical Review B, 1992

In x-ray-excited surface spectroscopies one of the most relevant figures of merit is the overlaye... more In x-ray-excited surface spectroscopies one of the most relevant figures of merit is the overlayer versus substrate signal ratio. In this work we propose to utilize the Borrmann (or anomalous-transmission) effect, which takes place in perfect crystals, in order to have a weaker interaction of the incident beam with the substrate. In this way the overlayer versus substrate signal ratio

Research paper thumbnail of Nature of the band gap of polycrystalline β-FeSi 2 films

We present experimental evidence for the indirect nature of the beta-FeSi2 gap. We furthermore sh... more We present experimental evidence for the indirect nature of the beta-FeSi2 gap. We furthermore show, by analyzing the temperature dependence of the direct gap by means of a thermodynamic empirical model, that beta-FeSi2 exhibits an unusually strong electron-phonon interaction. We finally deduce the electron-hole mobility from our measurements.

Research paper thumbnail of Structural study of the Si–alkali-metal interface with x-ray standing waves

Physical Review B, 1992

... Roma, Italy E. Fontes and JR Patel AT&T Bell Laboratories, Murray Hill, New J... more ... Roma, Italy E. Fontes and JR Patel AT&T Bell Laboratories, Murray Hill, New Jersey 07974 (Received 20 December 1991; revised manuscript received 29 June 1992) X-ray standing-wave measurements on Cs and Rb adlayers on the Si( 111)7 X 7 surface are presented. ...

Research paper thumbnail of Advancements in X-ray waveguides and their applications in coherent diffraction imaging

Radiation Physics and Chemistry, 2009

a b s t r a c t X-ray planar waveguides are currently used tools, in synchrotron radiation facili... more a b s t r a c t X-ray planar waveguides are currently used tools, in synchrotron radiation facilities, to produce a coherent beam with typical dimensions in the range of tens or hundreds of nanometers. The properties of waveguided beams such as divergence and coherence turns out to be very interesting for several applications both in synchrotron and in laboratory sources. These features will be reviewed in the present paper for different coupling methods of the radiation field with the waveguide channel. Details of fabrication procedures and experimental results concerning front coupling waveguide are reported. The waveguide properties can be estimated from the far-field diffracted beam by a Fourier analysis giving the autocorrelation function of the exit field. Due to the high degree of coherence of the exiting beam, X-ray waveguides can be successfully exploited in coherent diffraction imaging experiments. We review results concerning Fresnel coherent diffraction imaging experiments with hard X-rays, using planar waveguides as optical elements in one and two dimensions.

Research paper thumbnail of An automatic analysis of strain-depth profile in X-ray microdiffraction

Physica B: Condensed Matter, 2004

... The waveguide has been developed in collaboration with Werner Jark and SilviaDi Fonzo from El... more ... The waveguide has been developed in collaboration with Werner Jark and SilviaDi Fonzo from Elettra-Sincrotrone Trieste (IT). The authors thank the ID32 staff of ESRF for the very helpful collaboration during the experiment. ...

Research paper thumbnail of X-ray phase contrast microscopy at 300 nm resolution with laboratory sources

Optics Express, 2010

We report the performance of an X-ray phase contrast microscope for laboratory sources with 300 n... more We report the performance of an X-ray phase contrast microscope for laboratory sources with 300 nm spatial resolution. The microscope is based on a commercial X-ray microfocus source equipped with a planar X-ray waveguide able to produce a sub-micrometer x-ray beam in one dimension. Phase contrast images of representative samples are reported. The achieved contrast and resolution is discussed for different configurations. The proposed approach could represent a simple, inexpensive, solution for sub-micrometer resolution imaging with small laboratory setups.

Research paper thumbnail of Analysis of tapered front-coupling X-ray waveguides

Journal of Synchrotron Radiation, 2010

The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with v... more The coupling and propagation of electromagnetic waves through planar X-ray waveguides (WG) with vacuum gap and Si claddings are analyzed in detail, starting from the source and ending at the detector. The general case of linearly tapered WGs (i.e. with the entrance aperture different from the exit one) is considered. Different kinds of sources, i.e. synchrotron radiation and laboratory desk-top sources, have been considered, with the former providing a fully coherent incoming beam and the latter partially coherent beams. It is demonstrated that useful information about the parameters of the WG can be derived, comparing experimental results with computer simulation based on analytical solutions of the Helmholtz equation which take into account the amplitude and phase matching between the standing waves created in front of the WG, and the resonance modes propagating into the WG.

Research paper thumbnail of Periodically structured X-ray waveguides

Journal of Synchrotron Radiation, 2013

Author(s) of this paper may load this reprint on their own web site or institutional repository p... more Author(s) of this paper may load this reprint on their own web site or institutional repository provided that this cover page is retained. Republication of this article or its storage in electronic databases other than as specified above is not permitted without prior permission in writing from the IUCr.

Research paper thumbnail of Multisite occupancy at the alkali/silicon (111) interface studied with XSW

Journal of Physics D: Applied Physics, 1993

In this paper the authors report the results of an X-ray standing wave (XSW) study of an Si(111) ... more In this paper the authors report the results of an X-ray standing wave (XSW) study of an Si(111) 7*7-alkali metal (Cs,Rb) interface as a function of coverage. The three-fold hollow (H3) site, the three-fold filled (T4) site and all the dangling bond sites (atop, adatoms and vacancy) have been considered as available sites at the Si surface for the adsorbate.

Research paper thumbnail of X-ray waveguides for laboratory sources

Journal of Physics D: Applied Physics, 2005

A planar x-ray waveguide (WG) consisting of a diamond-like carbon layer sandwiched between two Ni... more A planar x-ray waveguide (WG) consisting of a diamond-like carbon layer sandwiched between two Ni layers is used to demonstrate for the first time the possibility of using WGs as optical elements with standard laboratory sources. The exit beam profile for the first two guided modes has been measured and analysed to demonstrate the high degree of beam coherence. The exit divergence and the beam size are reported and compared with theoretical predictions. Other relevant parameters, such as efficiency and gain, have been measured. This opens up interesting perspectives for the production of nanometre-sized x-ray beams with table-top laboratory sources.

Research paper thumbnail of In situ and ex situ structural characterization of β-FeSi2 films epitaxially grown on Si(111)

Journal of Applied Physics, 1992

The structural properties of β-FeSi2 films grown on Si(111) are studied by means of several techn... more The structural properties of β-FeSi2 films grown on Si(111) are studied by means of several techniques. The films were grown in ultrahigh vacuum by solid phase epitaxy. The as-deposited Fe films were studied in situ by low energy electron diffraction (LEED) and Auger spectroscopy. Fe thicknesses were calibrated by Rutherford backscattering. The behavior of the FeMVV/SiLVV Auger peaks ratio intensity

Research paper thumbnail of X-ray characterization of Si microstructures with high spatial resolution

Journal of Applied Physics, 2004

With the advent of the nanolithographic technologies, the demand of a local strain/stress analysi... more With the advent of the nanolithographic technologies, the demand of a local strain/stress analysis with submicrometer resolution is increasing. In particular, the aim of this work was the study of a patterned Si wafer subjected to preliminary process flow for 0.15 m complementary metal oxide semiconductor generation. The main purpose was to follow the production of strain induced in the Si substrate during the shallow trench isolation process and subsequent formation of active stripes. The determination of structural parameters with very high spatial resolution in one dimension ͑300 nm͒ has been obtained using a scanning x-ray microscope whose main element is a waveguide for medium and high energy x-rays ͑8 -30 keV͒. The experiment, which takes advantage of a nondispersive geometry, required neither a two-dimensional highly sensitive detector nor an insertion device beamline, but it has been carried out on bending magnet beamlines with relatively low flux.

Research paper thumbnail of Computer simulations and experimental results on air-gap X-ray waveguides

Spectrochimica Acta Part B: Atomic Spectroscopy, 2007

X-ray Waveguides (WG) are optical elements able to provide nanometer size coherent X-ray beams. B... more X-ray Waveguides (WG) are optical elements able to provide nanometer size coherent X-ray beams. Both Resonant beam Coupling (RBC) and Front Coupling (FC) can be implemented to couple the incident radiation with the WG. In this paper we implemented a computer code based on finite difference scheme solutions of parabolic wave equations to simulate the coupling and the propagation of electromagnetic waves into air-gap waveguides in Front Coupling mode. Both a synchrotron source and a table-top laboratory sources have been considered. In this last case the degree of coherence of the incoming beam has been explicitly taken into consideration. Air-gap WGs have been fabricated following simple procedures, and tested at the Elettra synchrotron source. The results are in good agreement with theoretical expectations.