Luca Gavioli | Università Cattolica del Sacro Cuore (Catholic University of the Sacred Heart) (original) (raw)

Papers by Luca Gavioli

Research paper thumbnail of One- and Two-Dimensional Systems: Scanning Tunneling Microscopy and Spectroscopy of Organic and Inorganic Structures

NanoScience and Technology, 2006

Research paper thumbnail of Experimental and Theoretical Scanning Tunneling Spectroscopy Analysis of an Ultrathin Titania Film and Adsorbed Au Nanoparticles

The Journal of Physical Chemistry C, 2014

ABSTRACT We present a detailed experimental and theoretical investigation of the ultrathin titani... more ABSTRACT We present a detailed experimental and theoretical investigation of the ultrathin titania z′-TiOx/Pt(111) phase and Au nanoparticles assembled on it. Scanning tunneling spectroscopy (STS) at two different tip stabilization biases (TSB) is measured at three different locations on the bare titania phase and on top of the Au nanoparticles (NPs). STS data are compared with the results of first-principles calculations based on a Tersoff–Hamann approach for simulating tunneling currents. We obtain a coherent framework in which STS features can be used as fingerprints with atomistic resolution of the local density of states. On the bare titania, Shockley states coming from the O atoms dominate the occupied DOS, while resonant states coming from the Ti atoms dominate the DOS above the Fermi level. The ultrathin film is partially metallized, with DOS empty channels at the hole sites, hence lying in an intermediate state between a semiconducting oxide and a conductor. Finally, STS data on top of Au nanoparticles provide information on the coordination environment of the Au atom in direct contact with the titania phase, discriminating between the Au metallic or nonmetallic régime.

Research paper thumbnail of The nature of the Fe–graphene interface at the nanometer level

Nanoscale, 2015

The emerging fields of graphene-based magnetic and spintronic devices require a deep understandin... more The emerging fields of graphene-based magnetic and spintronic devices require a deep understanding of the interface between graphene and ferromagnetic metals. This paper reports a detailed investigation at the nanometer level of the Fe-graphene interface carried out by angle-resolved photoemission, high-resolution photoemission from core levels, near edge X-ray absorption fine structure, scanning tunnelling microscopy and spin polarized density functional theory calculations. Quasi-free-standing graphene was grown on Pt(111), and the iron film was either deposited atop or intercalated beneath graphene. Calculations and experimental results show that iron strongly modifies the graphene band structure and lifts its π band spin degeneracy.

Research paper thumbnail of Electronic structure: Wide-band, narrow-band, and strongly correlated systems-Anomalous spectral weight in photoemission spectra of the hole-doped Haldane chain Y2-xSrxBaNiO5

Research paper thumbnail of Photoemission spectroscopy study of the hole-doped Haldane chain Y 2− x Sr x BaNiO 5

In this paper, we present photoemission experiments on the hole-doped Haldane chain compound Y2−x... more In this paper, we present photoemission experiments on the hole-doped Haldane chain compound Y2−xSrxBaNiO5. By using the photon energy dependence of the photoemission cross section, we identified the symmetry of the first ionisation states (d type). Hole doping in this system leads to a significant increase in the spectral weight at the top of the valence band without any change

Research paper thumbnail of Semiconductors II: Surfaces, interfaces, microstructures, and related topics-Atomic topography and self-assembly of one-dimensional potassium chains on the InAs (110) surface

Research paper thumbnail of Quasi–one-dimensional electronic state of alkali metal chains assembled on the InAs (110) surface

We investigate the electronic band dispersion associated to alkali metal chains assembled on the ... more We investigate the electronic band dispersion associated to alkali metal chains assembled on the InAs(110) surface by angular-resolved photoelectron spectroscopy. The Cs and K atomic chains induce occupied electronic states with twofold symmetry and narrow bandwidth along the chain direction, showing a quasi one-dimensional electronic character. The insulating character and the narrow bandwidth of the alkali-induced state suggest the relevance

Research paper thumbnail of Scanning Tunneling Microscopy Studies of Nanotubelike Structures on the Hopg Surface

Advanced Study Institutes are high-level tutorial courses offering in-depth study of latest advan... more Advanced Study Institutes are high-level tutorial courses offering in-depth study of latest advances in a field. Advanced Research Workshops are expert meetings aimed at critical assessment of a field, and identification of directions for future action.

Research paper thumbnail of Transformation of femtoliter metal cups to oxide cups: chemical mapping by scanning Auger spectroscopy

Applied Physics A, 2007

Cup-like structures of In, Sn and Nb on Si substrates with femtoliter capacity obtained by pulsed... more Cup-like structures of In, Sn and Nb on Si substrates with femtoliter capacity obtained by pulsed laser ablation, have been subjected to different oxidation treatments and examined employing spatially resolved scanning Auger spectroscopy and microscopy (SR-AES and SAM). The as-prepared cups, when exposed to ambient conditions are found to have a native oxide layer at the surface that could be easily removed by Ar ion sputtering, resulting in clean metal cups, suitable for functionalization. In the case of In cups, the thin metal layer at the bottom of the cups could be easily removed by sputtering to form In rings. Cups subjected to an external oxidation treatment have a thicker oxide layer in comparison to in-situ dosing of oxygen. In the case of Nb cups, the high temperature treatment employed during oxidation resulted in the segregation of Si to the surface of the cups. There is also evidence for the formation of a metal-silicon alloy at the center of the cups, especially in the case of Sn and Nb, during the oxidation treatment at elevated temperatures.

Research paper thumbnail of Orientation of C60 molecules in the (3 (bent radical) 3X3 (bent radical) 3) R30 (degree) and ((bent radical) 13X (bent radical) 13) R14 (degree) phases of C60/Ge (111) single layers

Research paper thumbnail of Mechanism Of Fe Nanoparticles' Growth On Graphite Surface With Defects

Research paper thumbnail of The dynamics of Fe intercalation on pure and nitrogen doped graphene grown on Pt (111) probed by CO adsorption

ABSTRACT In this paper we compare by temperature programmed desorption the intercalation rate of ... more ABSTRACT In this paper we compare by temperature programmed desorption the intercalation rate of Fe nanoparticles supported on pure and nitrogen doped graphene grown on Pt (111).

Research paper thumbnail of Ultrathin Fullerene-Based films via STM and STS

This chapter overviews the major results obtained by scanning tunneling microscopy and spectrosco... more This chapter overviews the major results obtained by scanning tunneling microscopy and spectroscopy on systems including the C60 molecule, starting from the free C60 molecule up to C60 in the solid state. The structural and electronic properties of fullerene films are described. Moreover, the behavior of fullerenes in low-dimensional films obtained by molecular deposition on clean metal and semiconductor substrates is reviewed, as well as the influence on the film properties by external doping.

Research paper thumbnail of Orientation of C 60 molecules in the (3 3× 3 3) R 30° and (13× 13) R 14° phases of C 60∕ Ge (111) single layers

Research paper thumbnail of Synthesis of photocatalytic TiO 2 nano-coatings by supersonic cluster beam deposition

In this paper we report on the photocatalytic behavior in gas phase propane oxidation of well-def... more In this paper we report on the photocatalytic behavior in gas phase propane oxidation of well-defined TiO 2 nanoparticle (NP) coatings prepared via Supersonic Cluster Beam Deposition (SCBD) on Si-wafers and quartz substrates. The temperature dependent crystal phase of the coatings was analyzed by Raman spectroscopy, and the morphology by High Resolution-Scanning Electron Microscopy.

Research paper thumbnail of Growth of curved graphene sheets on graphite by chemical vapor deposition

We report a synthesis route of a carbon-based structure, curved graphene sheet ͑CGS͒. The CGS gro... more We report a synthesis route of a carbon-based structure, curved graphene sheet ͑CGS͒. The CGS grows by catalytic chemical vapor deposition autoselectively at the stacked bilayer edges of graphite support, providing an atomically smooth connection of the edges. We propose a growth mechanism based on Fe nanoparticle diffusion along the step edges, acting as a nanozipper. The work addresses with a simple experimental method, the edge engineering in graphene bilayer systems. The results may have a significant impact on the fabrication of new carbon nanostructures and their integration into nanoelectronics.

Research paper thumbnail of Catalytic chemical vapor deposition of methane on graphite to produce graphene structures

Graphene structures, obtained by catalytic chemical vapor deposition of methane on highly oriente... more Graphene structures, obtained by catalytic chemical vapor deposition of methane on highly oriented pyrolitic graphite (HOPG), were examined using scanning tunneling microscopy.

Research paper thumbnail of Ag island nucleation on Ge (1 1 1)-c (2× 8)

Research paper thumbnail of Electronic properties of the Bi/Si (100) interface

Research paper thumbnail of Atomic topography and self-assembly of one-dimensional potassium chains on the InAs (110) surface

... Massimo Sancrotti Dipartimento di Matematica e Fisica and INFM, Università Cattolica del Sacr... more ... Massimo Sancrotti Dipartimento di Matematica e Fisica and INFM, Università Cattolica del Sacro Cuore, Via dei Musei 41, I-25121 Brescia ... 13 S. Modesti, A. Falasca, M. Polentarutti, MG Betti, V. De Renzi, and C. Mariani, Surf. ... 17 NJ Di Nardo, TM Wong, and EW Plummer, Phys. ...

Research paper thumbnail of One- and Two-Dimensional Systems: Scanning Tunneling Microscopy and Spectroscopy of Organic and Inorganic Structures

NanoScience and Technology, 2006

Research paper thumbnail of Experimental and Theoretical Scanning Tunneling Spectroscopy Analysis of an Ultrathin Titania Film and Adsorbed Au Nanoparticles

The Journal of Physical Chemistry C, 2014

ABSTRACT We present a detailed experimental and theoretical investigation of the ultrathin titani... more ABSTRACT We present a detailed experimental and theoretical investigation of the ultrathin titania z′-TiOx/Pt(111) phase and Au nanoparticles assembled on it. Scanning tunneling spectroscopy (STS) at two different tip stabilization biases (TSB) is measured at three different locations on the bare titania phase and on top of the Au nanoparticles (NPs). STS data are compared with the results of first-principles calculations based on a Tersoff–Hamann approach for simulating tunneling currents. We obtain a coherent framework in which STS features can be used as fingerprints with atomistic resolution of the local density of states. On the bare titania, Shockley states coming from the O atoms dominate the occupied DOS, while resonant states coming from the Ti atoms dominate the DOS above the Fermi level. The ultrathin film is partially metallized, with DOS empty channels at the hole sites, hence lying in an intermediate state between a semiconducting oxide and a conductor. Finally, STS data on top of Au nanoparticles provide information on the coordination environment of the Au atom in direct contact with the titania phase, discriminating between the Au metallic or nonmetallic régime.

Research paper thumbnail of The nature of the Fe–graphene interface at the nanometer level

Nanoscale, 2015

The emerging fields of graphene-based magnetic and spintronic devices require a deep understandin... more The emerging fields of graphene-based magnetic and spintronic devices require a deep understanding of the interface between graphene and ferromagnetic metals. This paper reports a detailed investigation at the nanometer level of the Fe-graphene interface carried out by angle-resolved photoemission, high-resolution photoemission from core levels, near edge X-ray absorption fine structure, scanning tunnelling microscopy and spin polarized density functional theory calculations. Quasi-free-standing graphene was grown on Pt(111), and the iron film was either deposited atop or intercalated beneath graphene. Calculations and experimental results show that iron strongly modifies the graphene band structure and lifts its π band spin degeneracy.

Research paper thumbnail of Electronic structure: Wide-band, narrow-band, and strongly correlated systems-Anomalous spectral weight in photoemission spectra of the hole-doped Haldane chain Y2-xSrxBaNiO5

Research paper thumbnail of Photoemission spectroscopy study of the hole-doped Haldane chain Y 2− x Sr x BaNiO 5

In this paper, we present photoemission experiments on the hole-doped Haldane chain compound Y2−x... more In this paper, we present photoemission experiments on the hole-doped Haldane chain compound Y2−xSrxBaNiO5. By using the photon energy dependence of the photoemission cross section, we identified the symmetry of the first ionisation states (d type). Hole doping in this system leads to a significant increase in the spectral weight at the top of the valence band without any change

Research paper thumbnail of Semiconductors II: Surfaces, interfaces, microstructures, and related topics-Atomic topography and self-assembly of one-dimensional potassium chains on the InAs (110) surface

Research paper thumbnail of Quasi–one-dimensional electronic state of alkali metal chains assembled on the InAs (110) surface

We investigate the electronic band dispersion associated to alkali metal chains assembled on the ... more We investigate the electronic band dispersion associated to alkali metal chains assembled on the InAs(110) surface by angular-resolved photoelectron spectroscopy. The Cs and K atomic chains induce occupied electronic states with twofold symmetry and narrow bandwidth along the chain direction, showing a quasi one-dimensional electronic character. The insulating character and the narrow bandwidth of the alkali-induced state suggest the relevance

Research paper thumbnail of Scanning Tunneling Microscopy Studies of Nanotubelike Structures on the Hopg Surface

Advanced Study Institutes are high-level tutorial courses offering in-depth study of latest advan... more Advanced Study Institutes are high-level tutorial courses offering in-depth study of latest advances in a field. Advanced Research Workshops are expert meetings aimed at critical assessment of a field, and identification of directions for future action.

Research paper thumbnail of Transformation of femtoliter metal cups to oxide cups: chemical mapping by scanning Auger spectroscopy

Applied Physics A, 2007

Cup-like structures of In, Sn and Nb on Si substrates with femtoliter capacity obtained by pulsed... more Cup-like structures of In, Sn and Nb on Si substrates with femtoliter capacity obtained by pulsed laser ablation, have been subjected to different oxidation treatments and examined employing spatially resolved scanning Auger spectroscopy and microscopy (SR-AES and SAM). The as-prepared cups, when exposed to ambient conditions are found to have a native oxide layer at the surface that could be easily removed by Ar ion sputtering, resulting in clean metal cups, suitable for functionalization. In the case of In cups, the thin metal layer at the bottom of the cups could be easily removed by sputtering to form In rings. Cups subjected to an external oxidation treatment have a thicker oxide layer in comparison to in-situ dosing of oxygen. In the case of Nb cups, the high temperature treatment employed during oxidation resulted in the segregation of Si to the surface of the cups. There is also evidence for the formation of a metal-silicon alloy at the center of the cups, especially in the case of Sn and Nb, during the oxidation treatment at elevated temperatures.

Research paper thumbnail of Orientation of C60 molecules in the (3 (bent radical) 3X3 (bent radical) 3) R30 (degree) and ((bent radical) 13X (bent radical) 13) R14 (degree) phases of C60/Ge (111) single layers

Research paper thumbnail of Mechanism Of Fe Nanoparticles' Growth On Graphite Surface With Defects

Research paper thumbnail of The dynamics of Fe intercalation on pure and nitrogen doped graphene grown on Pt (111) probed by CO adsorption

ABSTRACT In this paper we compare by temperature programmed desorption the intercalation rate of ... more ABSTRACT In this paper we compare by temperature programmed desorption the intercalation rate of Fe nanoparticles supported on pure and nitrogen doped graphene grown on Pt (111).

Research paper thumbnail of Ultrathin Fullerene-Based films via STM and STS

This chapter overviews the major results obtained by scanning tunneling microscopy and spectrosco... more This chapter overviews the major results obtained by scanning tunneling microscopy and spectroscopy on systems including the C60 molecule, starting from the free C60 molecule up to C60 in the solid state. The structural and electronic properties of fullerene films are described. Moreover, the behavior of fullerenes in low-dimensional films obtained by molecular deposition on clean metal and semiconductor substrates is reviewed, as well as the influence on the film properties by external doping.

Research paper thumbnail of Orientation of C 60 molecules in the (3 3× 3 3) R 30° and (13× 13) R 14° phases of C 60∕ Ge (111) single layers

Research paper thumbnail of Synthesis of photocatalytic TiO 2 nano-coatings by supersonic cluster beam deposition

In this paper we report on the photocatalytic behavior in gas phase propane oxidation of well-def... more In this paper we report on the photocatalytic behavior in gas phase propane oxidation of well-defined TiO 2 nanoparticle (NP) coatings prepared via Supersonic Cluster Beam Deposition (SCBD) on Si-wafers and quartz substrates. The temperature dependent crystal phase of the coatings was analyzed by Raman spectroscopy, and the morphology by High Resolution-Scanning Electron Microscopy.

Research paper thumbnail of Growth of curved graphene sheets on graphite by chemical vapor deposition

We report a synthesis route of a carbon-based structure, curved graphene sheet ͑CGS͒. The CGS gro... more We report a synthesis route of a carbon-based structure, curved graphene sheet ͑CGS͒. The CGS grows by catalytic chemical vapor deposition autoselectively at the stacked bilayer edges of graphite support, providing an atomically smooth connection of the edges. We propose a growth mechanism based on Fe nanoparticle diffusion along the step edges, acting as a nanozipper. The work addresses with a simple experimental method, the edge engineering in graphene bilayer systems. The results may have a significant impact on the fabrication of new carbon nanostructures and their integration into nanoelectronics.

Research paper thumbnail of Catalytic chemical vapor deposition of methane on graphite to produce graphene structures

Graphene structures, obtained by catalytic chemical vapor deposition of methane on highly oriente... more Graphene structures, obtained by catalytic chemical vapor deposition of methane on highly oriented pyrolitic graphite (HOPG), were examined using scanning tunneling microscopy.

Research paper thumbnail of Ag island nucleation on Ge (1 1 1)-c (2× 8)

Research paper thumbnail of Electronic properties of the Bi/Si (100) interface

Research paper thumbnail of Atomic topography and self-assembly of one-dimensional potassium chains on the InAs (110) surface

... Massimo Sancrotti Dipartimento di Matematica e Fisica and INFM, Università Cattolica del Sacr... more ... Massimo Sancrotti Dipartimento di Matematica e Fisica and INFM, Università Cattolica del Sacro Cuore, Via dei Musei 41, I-25121 Brescia ... 13 S. Modesti, A. Falasca, M. Polentarutti, MG Betti, V. De Renzi, and C. Mariani, Surf. ... 17 NJ Di Nardo, TM Wong, and EW Plummer, Phys. ...