Welcome to XPEEM and LEEM @ Elettra

The study of nanostructured materials requires analytical methods that combine X-ray spectroscopy with electron microscopy. The Nanospectroscopy beamline at Elettra operates a state-of-the-art spectroscopic photoemission and low energy electron microscope (SPELEEM). This powerful instrument offers a wide range of complementary methods providing structural, chemical and magnetic sensitivity. The lateral resolution of the microscope currently approaches few tens nm. The microscope is served by a high photon flux beamline, which can deliver elliptically polarized photons in the range 50 eV to 1000 eV. Research applications are targeted to Surface and Materials Sciences, addressing issues related to chemical and magnetic characterization of surfaces, interfaces, thin films, and nanostructures.

Research Highlights | Publications | Applications | Agenda | Calendar | End-station

Unveiling the formation of epitaxial graphene on cobalt

PEEM and LEEM enabled imaging the structural transformation that graphene on cobalt undergoes at temperatures above 500°C, from a rotationally-incoherent, defective layer to an epitaxial one.The structural transformation takes place via the growth and propagation of mesoscopic carbidic islands and involves the dissolution and recondensation of carbon.
M. Jugovac et al., Carbon 152, 489-496 (2019).

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In-Gap States and Band-Like Transport in Memristors

Laterally-resolved soft X-ray resonant photoelectron spectromicroscopy enabled direct access to the electronic structure of a conductive filament in an epitaxial memristive device. Oxygen vacancies in SrTiO3–x were found to induce the formation of in-gap states that impact the shape of the conduction band.
C. Baeumer et al., Nano Lett. 19, 54–60 (2019).

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Writing the magnetic state with carbon monoxide

We devised a new method to graft chemo-magnetic patterns by depositing atomic carbon through electron stimulated molecular dissociation. To do this, an ultra-thin cobalt film is exposed it to CO while irradiating the surface with an intense, micro-focused low energy electron beam.
P.  Genoni et al., ACS Applied Materials & Interfaces 10(32), 27178–27187 (2018).

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Subfilamentary Networks in Memristive Devices

In-operando XAS-PEEM gives access to  the microscopic origin of resitance variability in memristior devices based on transition metal oxides. Upon switching, the spatial rearrangement of oxygen vacancies results in variations of their local concentration and shape of the conductive filament bridging the metal electrodes.
C. Baeumer et al., ACS Nano 11, 6921 (2017).

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Graphene and h-BN by a Single Molecular Precursor

The fabrication of graphene h-BN layers is rather challenging. We report here a novel bottom-up approach to obtain a continuous almost free-standing hexagonal single layer with perfectly merging graphene and hexagonal boron-nitride domains using only one molecular precursor.
S. Nappini et al., Adv. Funct. Mater. 7, 1120 (2016).

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Stable magnetic skyrmions at room temperature

Magnetic skyrmions are chiral spin structures with a whirling configuration. By employing x-ray magnetic circular dichroism photoemission electron microscopy, we imaged for the first time the chiral Néel internal structure of stable skyrmions in sputtered ultrathin Pt/Co/MgO nanostructures at room temperature and zero external magnetic field.
O. Boulle et al., Nat. Nanotech. 11, 449 (2016).

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Fragmentation of magnetism in dipolar spin ice

Few cases exist where a system remains disordered as a gas or a liquid, even at the lowest temperatures accessible experimentally. Systems that simultaneously exhibit different order states  are even rarer.  Such a phase, “liquid” and “solid” at the same time, has been recently observed in a magnetic metamaterial, artificial spin ice.
B. Canals et al., Nat. Comm. 7, 11446  (2016);

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Island Ripening in a catalytic reaction

We have investigated a reaction-controlled ripening process of ultrathin vanadium oxide on Rh(111) during catalytic methanol oxidation. Under reaction conditions, neighboring vanadium oxide islands move towards each other and coalesce. This quasi-macroscopic ripening is explained by a polymerization-depolymerization mechanism which is sensitive to gradients in the adsorbate coverages.
M.  Hesse et al., Phys. Rev. Lett. 115, 136102 (2015).

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Fabrication of 2D heterojunction in graphene

Irradiation with very-low energy nitrogen ions is used to locally induce substitutional doping in graphene. Irradiated and non-irradiated areas are separated by a sharp boundary, stable up to 750 °C. Our experiments pave the way to the lithographic control of the electronic properties of graphene and provide a proof-of-principle for the fabrication of graphene-based heterojunctions.
A. Sala, Small 11(44), 5927–5931 (2015).

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Nanobubbles at extreme pressure under graphene

Graphene is able to trap mesoscopic volumes of liquid or gas, resulting in the formation of nanobubbles. Here we have investigated the morphology and spatial distribution of Ar under micron-sized graphene flakes supported on Ir(100), specifically addressing the dynamics of nanobubbles formation, their stability and the pressure which Ar is subject to. G. Zamborlini et al., Nano Lett. 15(9), 6162–6169 (2015).

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News | archive

LEEM/PEEM-11, Chongqing, PRC, October 31- November 3, 2018

LEEM-PEEM is a biennial meeting reviewing the status of LEEM, PEEM, SPLEEM, XPEEM and related techniques. The meeting promotes and disseminates applications of cathode lens microscopy to a broad audience of interested scientists. The workshop highlights the most recent scientific advances as well as instrumental developments. Topics will cover surfaces, thin films, organic films, surface chemistry, magnetism, time resolved methods, instrumental advances and novel applications of LEEM and PEEM to other subject areas. The 11th LEEM/PEEM workshop will be held at Westin Hotel in Chongqing, China. Dont'miss the workshop! to start with, visit the LEEM/PEEM 11 website.

Beamline developments

Monochromator upgrade

We inform our users that the upgrade of the monochromator has been successfully completed and that the instrument is now fully operational. The monochromator was modified to solve long term stability issues and improve mechanical and optical operation. The monochromator is now extremely stable. A brief report on the monochromator performance is available here.

Detector Gating for Time Resolved Measurements

In order to exploit the pulsed structure of synchrotron radiation in stroboscopic experiments, the imaging detector of the PEEM needs to be gated. The gating allows to activate the detector only after the specimen has been taken into an excited state. So far, gating has been done by applying a voltage pulse to the MCP output-plate, a solution that impacts negatively on the detector lifetime. We have developed a novel approach, where gating is done by an electrode inserted in the middle of the beam splitter. The electrode can deflect the e-beam, which is let through the contrast aperture or it is stopped on its surroundings. 

A high pressure chamber for the SPELEEM

A new high pressure chamber has been constructed and attached to the SPELEEM microscope as an ancillary facility for catalysis experiments. The high pressure chamber enables us to probe the sample using mass spectrometry via time analysis of reaction products. The chamber has been designed and developed in house, in collaboration with Prof. Mike Altman (Hong Kong University of Science and technology) and Prof. Ernst Bauer (Arizona State University). Please contact the personnel in charge if you are interested in further information or you want to collaborate.

NanoESCA beamline

A NanoESCA microscope (Omicron - Focus, GmbH) has been installed and commissioned on the Nanospectroscopy beamline second branch. The microscope is an electrostatic PEEM with double-pass hemispherical analyzer. The instrument is managed by an international consortium led by Forschungszentrum Jülich (Peter Grünberg Institute). The branchline has been open to Elettra general users in January 2012, with the name of NanoESCA. The NanoESCA website offers a wide perspective on the types of measurements that can be carried out with this instrument.

User Area

Proposal Submission

We invite users to discuss their proposals with the beamline contacts well in advance before the submission deadline. This is crucial for a careful assessment of the experiment feasibility and may lead to improvements in the proposed experimental plan. In a restricted number of cases, when doubts arise about the suitability of your samples or the planned measurements are too close to the microscope resolution limit, it may be possible for you to arrange a test. For more info, please visit the user info section.

Call for proposals

The deadline for proposal submission for beamtime allocation during the second semester of the current year is March 15th, 2021. Please indicate Nanospectroscopy as first beamline if your experiment requires using the SPELEEM microscope.

Sample cooling

The SPELEEM sample cooling stage has been reparied and upgraded. It is currently under commissioning.

Access through CERIC

Nanospectroscopy is part of the CERIC-ERIC consortium. CERIC-ERIC offers access to more than 40 different and complementary state of the art techniques, distributed in 8 countries, with the submission of single or multi-technique proposals through a single entry point.

Ultima modifica il Giovedì, 04 Marzo 2021 00:17