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Research

 

The group scientific activity is principally devoted to the study of electronic and magnetic properties of a large variety of solid materials ranging from  superconductors to organic and inorganic molecular adsorbates, ultra-thin oxide films and surface alloys. We are interested in the chemical and electronic properties, in the surface reactivity, surface structure and dynamical processes. Research applications are targeted to surface and materials sciences, physics and chemistry, but the same x-ray spectroscopy techniques can be used and has been used also to address topics of geochemistry, mineralogy, medical science, environmental science, bio-chemistry, astrophysics.
To this purpose, we use the wide range of techniques, all available at the same ultra-high-vacuum endstation A: X-ray Photoelectron Spectroscopy (including Angle-Resolved Photoelectron Spectroscopy and XPD), X-Ray Emission,  X-Ray Magnetic Circular Dichroism (in remanence), Low Energy Electron Diffraction, Molecular and Electron Beam Epitaxy.
Morover recently we Time-resolved X-Ray Absorption in the sub-nsec regime has been developed.

The spectroscopic methods available at the BACH beamline have been applied in several fields of modern condensed matter physics, for example on thin molecular and self-assembled overlayers on metal and thin oxide surfaces, single-layer, layered materials and 2D heterostructures, oxide thin films and interfaces, electron correlated materials, superconductors, and novel magnetic materials. The investigations are mostly focused on understanding the interplay between electronic, structural, magnetic, and functional properties and the mechanisms of interaction among different degrees of freedom in these systems. Chemical reactions at surface, such as heterogeneous catalysis, on-surface polymerization, surface and subsurface alloying as well as the stability of low-dimensional and layered materials in humid, oxidative, hydrogen or ambient environments can be also tackled thanks to the surface and chemical sensitivity of the available spectroscopic methods. More recently the X-ray- based spectroscopic techniques have been integrated on BACH beamline for the study of liquid and on the liquid/solid interfaces to enable the comprehensive understanding of the electron transfer processes during chemical reactions. This goal has been pursued by the encapsulation of fluids between a thin membrane and a solid substrate.
 

Browse our Publications

Read our Highlights


2D materials and interface chemical physics

Our activities in the field of 2D materials are focused on surface-assisted synthesis of doped graphene and 2D in-plane hexagonal boron nitride – graphene heterostructures. It has been only recently recognized thatheterogeneous catalysis can take place in the confined space between a solid catalyst and a weakly interacting two-dimensional (2D) overlayer. This peculiar space can be regarded as a nanoreactor, where confined molecule adsorption and surface reactions may occur. Even more enhanced catalytic performance could be exhibited by hybrid layers in which two or more materials are combined. We are examining the confinement effects and the reactions in the nanospace between an in-plane heterostructure of graphene and hexagonal boron nitride and platinum substrate. Furthermore, we have succeeded to fabricate sealed graphene nanobubbles filled with aqueous solutions between a graphene layer and a TiO2 crystal which allows us to study thermo- and photo-induced reactions.

Chemical reactions at surfaces

Tunable source of excitation energy, high-resolution XPS and soft x-ray XAS permit us to significantly enhance surface sensitivity as well as sensitivity to certain elements (e.g., nitrogen, sulfur, lithium, carbon, oxygen, chalcogens, top-most atoms). The high sensitivity to their chemical states is being exploited in the study of chemical reactions at surfaces, such as heterogeneous catalysis, on-surface polymerization, surface and subsurface alloying. We are studying growth, intercalation, and chemical reactivity of 2D materials; growth of graphene nanoribbons from halogenated molecular precursors by surface-assisted catalysis; photocatalytic reactions in nanobubbles trapped under graphene.

Transition metal dichalcogenides

Transition metal dichalcogenides (TMDC) represent a family of materials typically in the form of MX2 where M is the transition metal and X is the chalcogen (S, Se, Te). Most TMDC bulk crystals are layered solids with strong bonding within the plane but weak interlayer bonding. Dopant atoms may intercalate between layers and appropriate dopant selection and concentration can improve the performance of TMDCs. On the other hand, improper doping might have unwanted effects. Understanding the principles and mechanisms yielding the phases with desired or undesired properties is an important prerequisite to engineer materials with tailored functionalities. In collaboration with several external research groups, we study the composition and electronic structure of new TMDC materials or TMDC synthesized by novel methods.

Nanomaterials

The wide photon energy range and high-resolution XPS are very suitable for the non-destructive chemical composition depth profiling of nanostructures, such as nanoparticles and nanotubes. XPS depth profiling of such non-planar objects is not available in standard laboratory conditions, because it requires a tunable photon source. This technique has been used at BACH beamline for the chemical composition analysis of quantum dots (QD) solar cells, nanocrystals of semiconducting material which offer great potential as the light-harvesting elements in next-generation solar cells.

Spectroscopy in liquids and at liquid/solid interfaces

XPS and XAS techniques have been successfully used at BACH beamline to follow thermo- and photo-induced reactions in liquid phase. This goal has been pursued by the encapsulation of fluids between a thin membrane and a solid substrate. This research line is developing on BACH beamline following new strategies, as the use of micro electrochemical cells suitable for photocatalytic or electrochemical reactions, such as CO2RR, ORR, OER and water splitting.


Some of the funded projects/proposals

AHEAD 2020

AHEAD 2020 Integrated Activity for the High Energy Astrophysics Domain
Project funded by Horizon 2020 Framework Program of the European Union Grant Agreement n. 871158

L. Piro (project coordinator) INAF/Institute of Space Astrophysics and Planetology (IAPS)
S. Sciortino  (coordinator of the Transnational Access Activity WP5) INAF/Palermo Astronomical Observatory
M. Coreno (CNR coordinator) ISM-CNR
E. Magnano (deputy for CNR, coordinator TA1) IOM-CNR
S. Nappini, F. Bondino, A. Giglia, N. Mahne, M. De Simone  IOM-CNR (partecipants)


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CNR-SAS JOINT RESEARCH PROJECT 2020-2021

    

Scientific Cooperation between the National Reseacrh Council (CNR) and the Slovak Academy of Science (SAS)
Optimization of the scalable growth of transition metal dichalcogenide thin films and novel heterostructures for application in electronics and advanced sensors

F. Bondino (coordinator - CNR)
M. Sojakova (coordinator - SAS)
I. Píš, S. Nappini, E. Magnano IOM-CNR partecipants




FIRB-Futuro in Ricerca

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Beyond graphene (Full list of publications)
Publications funded by FIRB performed at the BACH beamline by the IOM-CNR BACH research unit
NOTE: Reseach on graphene at BACH is also supported by MIUR through the program `Progetto Premiale 2012' - Project ABNANOTECH

Project funded by MIUR
F. Bondino (local coordinator), S. NappiniE. Magnano IOM-CNR
L. Savio (local coordinator)- IMEM-CNR
S. Agnoli (local coordinator)-Università di Padova
C. Di Valentin (national coordinator)- Università di Milano Bicocca

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IOM Start up
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Determining the Density of electronic states of DNA - D3
 
Elena Magnano (coordinator), Silvia Nappini, Federica Bondino  Sede TS-TASC – Beamline BACH.
Paolo Umari, Stefano Baroni, Alessandra Magistrato  Sede TS-DEMOCRITOS
Marco Lazzarino, Gianluca Grenci Sede TS-TASC
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Progetti in kind (PIK)

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EX-PRO-REL: EXcitation PROcesses and RELaxation in condensed matter and nanostructures: methodological, instrumental, and scientific challenges

Coordinator: Federico Boscherini
(Università di Bologna)
Partecipants: E. Magnano, F. Bondino
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PRIN 2012

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More information soon

Coordinator: M. Casarin (Università di Padova)
Local Coordinator: S. Pagliara (Università Cattolica di Brescia)
Partecipants: E. Magnano
Read more...


 

A multi-technique approach for the study of solid samples and surfaces

X-ray emission spectroscopy

X-ray emission spectroscopy (XES) provides a means of probing the partial occupied density of electronic states of a material. XES is element-specific and site-specific, making it a powerful tool for determining detailed electronic properties of materials. Emission spectroscopy can take the form of either resonant inelastic X-ray emission spectroscopy (RIXS) or non-resonant X-ray emission spectroscopy (NXES). Both spectroscopies involve the photonic promotion of a core level electron, and the measurement of the fluorescence that occurs as the electron relaxes into a lower-energy state.

X-ray Photoelectron Spectroscopy

X-ray Photoelectron Spectroscopy (XPS) is a quantitative spectroscopic technique that measures the elemental composition, chemical state and electronic state of the elements within a material. XPS spectra are obtained by irradiating a material with a beam of X-rays while simultaneously measuring the kinetic energy and number of electrons that escape from the top layers of the material being analyzed. XPS  can be used to analyze the surface chemistry of a material in its "as received" state, or after some treatment, for example: fracturing, cutting or scraping in UHV to expose the bulk chemistry, ion beam etching to clean off some of the surface contamination, exposure to heat to study the changes due to heating, exposure to reactive gases. Temperature-programmed fast XPS measurements can be performed.


X-Ray Absorption Spectroscopy

Soft-X-ray absorption spectroscopy (XAS) is technique for determining the local electronic structure of matter. XAS data are obtained by tuning the photon energy to a range where core electrons can be excited. Polarization-dependent XAS measuremnts can be performed.

Time-resolved Pump-Probe X-Ray Absorption Spectroscopy

Time-resolved x-ray absorption spectroscopy is the study of dynamic processes in materials or chemical compounds by means of x-ray abspectroscopic techniques. With the help of pulsed lasers, it is possible to study processes that occur on time scales in the sub-nanosec range.


Angle-resolved photoemission spectroscopy

Angle-resolved photoemission spectroscopy (ARPES) is an experimental technique to observe the distribution of the density of single-particle electronic excitations in the reciprocal space of solids.

ARPES gives information on the direction, speed and scattering process of valence electrons in the sample being studied (usually a solid). This means that information can be gained on both the energy and momentum of an electron, resulting in detailed information on band dispersion and Fermi surface. Both VUV ARPES and SOFT X-RAY ARPES can be performed.

X-ray magnetic circular dichroism

X-ray magnetic circular dichroism (XMCD) is a difference spectrum of two x-ray absorption spectra (XAS) taken in a magnetic field, one taken with left circularly polarized light, and one with right circularly polarized light. By closely analyzing the difference in the XMCD spectrum, information can be obtained on the magnetic properties of the atom, such as its spin and orbital magnetic moment. 



Photoelectron Diffraction

When a radiation field excites an atomic core-level,  the outgoing electron goes through a scattering process with the surrounding atoms. The quantum-mechanical interference of the directly emitted component of the photo-ejected electron wave-field with other components scattered coherently (in space and time) from neighbor atoms produces a Photoelectron Diffraction (PhD, PED or XPD) pattern that is characteristic for each emitter site.

LEED

Since the formation of the first electron diffraction patterns in 1927 by Davisson and Germer, who explained the physical phenomenon in terms of wave nature of electrons, Low Energy Electron Diffraction has been widely used for surface crystallography studies. LEED is not only a powerful tool for the qualitative identification of surface symmetries and two-dimensional periodicities, but it is the most used technique for quantitative structure determination of ordered surfaces.



Ultima modifica il Mercoledì, 10 Marzo 2021 11:34