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1. The new FAST module: a portable and transparent add-on module for time-resolved investigations with commercial scanning probe microscopes

Author

Dri, Carlo, Panighel, Mirco, Tiemann, Daniel, Patera, Laerte L., Troiano, Giulia, Fukamori, Yves, Knoller, Fabian, Lechner, Barbara A. J., Cautero, Giuseppe, Giuressi, Dario, Comelli, Giovanni, Fraxedas, Jordi, Africh, Cristina, and Esch, Friedrich

Subjects
Physics - Instrumentation and Detectors, Condensed Matter - Materials Science
Abstract

Time resolution is one of the most severe limitations of scanning probe microscopies (SPMs), since the typical image acquisition times are in the order of several seconds or even few minutes. As a consequence, the characterization of dynamical processes occurring at surfaces (e.g. surface diffusion, film growth, self-assembly and chemical reactions) cannot be thoroughly addressed by conventional SPMs. To overcome this limitation, several years ago we developed a first prototype of the FAST module, an add-on instrument capable of driving a commercial scanning tunneling microscope (STM) at and beyond video rate frequencies. Here we report on a fully redesigned version of the FAST module, featuring improved performance and user experience, which can be used both with STMs and atomic force microscopes (AFMs), and offers additional capabilities such as an atom tracking mode. All the new features of the FAST module, including portability between different commercial instruments, are described in detail and practically demonstrated.

Published
2019
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5. A novel free-electron laser single-pulse Wollaston polarimeter for magneto-dynamical studies

Author

Caretta, Antonio, primary, Laterza, Simone, additional, Bonanni, Valentina, additional, Sergo, Rudi, additional, Dri, Carlo, additional, Cautero, Giuseppe, additional, Galassi, Fabio, additional, Zamolo, Matteo, additional, Simoncig, Alberto, additional, Zangrando, Marco, additional, Gessini, Alessandro, additional, Zilio, Simone Dal, additional, Flammini, Roberto, additional, Moras, Paolo, additional, Demidovich, Alexander, additional, Danailov, Miltcho, additional, Parmigiani, Fulvio, additional, and Malvestuto, Marco, additional

Published
2021
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6. A novel free-electron laser single-pulse Wollaston polarimeter for magneto-dynamical studies

Author

Caretta, Antonio, Laterza, Simone, Bonanni, Valentina, Sergo, Rudi, Dri, Carlo, Cautero, Giuseppe, Galassi, Fabio, Zamolo, Matteo, Simoncig, Alberto, Zangrando, Marco, Gessini, Alessandro, Dal Zilio, Simone, Flammini, Roberto, Moras, Paolo, Demidovich, Alexander, Danailov, Miltcho, Parmigiani, Fulvio, Malvestuto, Marco, Caretta, Antonio, Laterza, Simone, Bonanni, Valentina, Sergo, Rudi, Dri, Carlo, Cautero, Giuseppe, Galassi, Fabio, Zamolo, Matteo, Simoncig, Alberto, Zangrando, Marco, Gessini, Alessandro, Dal Zilio, Simone, Flammini, Roberto, Moras, Paolo, Demidovich, Alexander, Danailov, Miltcho, Parmigiani, Fulvio, and Malvestuto, Marco

Abstract

Here, we report on the conceptual design, the hardware realization, and the first experimental results of a novel and compact x-ray polarimeter capable of a single-pulse linear polarization angle detection in the extreme ultraviolet photon energy range. The polarimeter is tested by performing time resolved pump-probe experiments on a Ni80Fe20 Permalloy film at the M-2,M-3 Ni edge at an externally seeded free-electron laser source. Comparison with similar experiments reported in the literature shows the advantages of our approach also in view of future experiments.

Published
2021

7. Multi-orbital charge transfer at highly oriented organic/metal interfaces

Author

Zamborlini, Giovanni, Lüftner, Daniel, Feng, Zhijing, Kollmann, Bernd, Puschnig, Peter, Dri, Carlo, Panighel, Mirko, Di Santo, Giovanni, Goldoni, Andrea, Comelli, Giovanni, Jugovac, Matteo, Feyer, Vitaliy, Schneider, Claus Michael, Zamborlini, Giovanni, Lüftner, Daniel, Feng, Zhijing, Kollmann, Bernd, Puschnig, Peter, Dri, Carlo, Panighel, Mirko, Di Santo, Giovanni, Goldoni, Andrea, Comelli, Giovanni, Jugovac, Matteo, Feyer, Vitaliy, and Schneidery, Claus Michael

Subjects
organic/metal interfaces, Science, porphyrin molecules, charge transfer, Physik (inkl. Astronomie), porphyrins, Publisher Correction, Article, adsorption, porphyrin molecules, molecule-metal interface, adsorption, lcsh:Q, ddc:500, lcsh:Science, organic/metal interface
Abstract

The molecule–substrate interaction plays a key role in charge injection organic-based devices. Charge transfer at molecule–metal interfaces strongly affects the overall physical and magnetic properties of the system, and ultimately the device performance. Here, we report theoretical and experimental evidence of a pronounced charge transfer involving nickel tetraphenyl porphyrin molecules adsorbed on Cu(100). The exceptional charge transfer leads to filling of the higher unoccupied orbitals up to LUMO+3. As a consequence of this strong interaction with the substrate, the porphyrin’s macrocycle sits very close to the surface, forcing the phenyl ligands to bend upwards. Due to this adsorption configuration, scanning tunneling microscopy cannot reliably probe the states related to the macrocycle. We demonstrate that photoemission tomography can instead access the Ni-TPP macrocycle electronic states and determine the reordering and filling of the LUMOs upon adsorption, thereby confirming the remarkable charge transfer predicted by density functional theory calculations., Charge transfer at molecule-metal interfaces affects the overall physical and magnetic properties of organic-based devices, and ultimately their performance. Here, the authors report evidence of a pronounced charge transfer involving nickel tetraphenyl porphyrin molecules adsorbed on copper.

Published
2017

8. Photoionization Dynamics of the Tetraoxo Complexes OsO4 and RuO4

Author

Schio, Luca, Alagia, Michele, Toffoli, Daniele, Decleva, Piero, Richter, Robert, Schalk, Oliver, Thomas, Richard D., Mucke, Melanie, Salvador, Federico, Bertoch, Paolo, Benedetti, Davide, Dri, Carlo, Cautero, Giuseppe, Sergo, Rudi, Stebel, Luigi, Vivoda, Davide, Stranges, Stefano, Schio, Luca, Alagia, Michele, Toffoli, Daniele, Decleva, Piero, Richter, Robert, Schalk, Oliver, Thomas, Richard D., Mucke, Melanie, Salvador, Federico, Bertoch, Paolo, Benedetti, Davide, Dri, Carlo, Cautero, Giuseppe, Sergo, Rudi, Stebel, Luigi, Vivoda, Davide, and Stranges, Stefano

Abstract

The photoionization dynamics of OsO4 and RuO4, chosen as model systems of small-size mononuclear heavy-metal complexes, has been theoretically studied by the time-dependent density functional theory (TDDFT). Accurate experimental measurements of photoionization dynamics as a benchmarking test for the theory are reported for the photoelectron asymmetry parameters of outer valence ionizations of OsO4, measured in the 17–90 eV photon energy range. The theoretical results are in good agreement with the available experimental data. The observed dynamical behavior of partial cross sections and asymmetry parameters has been related to both the coupling to the continuum of discrete excited states, giving strong modulations in the photon energy dependency, and the atomic composition of the initial ionized states, which determines the rate of decay of ionization probability for increasing excitation energies. Overall, an extensive analysis of the photoionization dynamics for valence and core orbitals is presented, showing good agreement with all the available experimental data. This provides confidence for the validity of the TDDFT approach in describing photoionization of heavy transition element compounds, with the perspective of being used for larger systems. Further experimental work is suggested for RuO4 to gather evidence of the sensitivity of the theoretical method to the nature of the metal atom.

Published
2020
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10. Photoionization Dynamics of the Tetraoxo Complexes OsO4 and RuO4

Author

Schio, Luca, primary, Alagia, Michele, additional, Toffoli, Daniele, additional, Decleva, Piero, additional, Richter, Robert, additional, Schalk, Oliver, additional, Thomas, Richard D., additional, Mucke, Melanie, additional, Salvador, Federico, additional, Bertoch, Paolo, additional, Benedetti, Davide, additional, Dri, Carlo, additional, Cautero, Giuseppe, additional, Sergo, Rudi, additional, Stebel, Luigi, additional, Vivoda, Davide, additional, and Stranges, Stefano, additional

Published
2020
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11. Experimental and Theoretical Photoemission Study of Indole and Its Derivatives in the Gas Phase

Author

Plekan, Oksana, primary, Sa’adeh, Hanan, additional, Ciavardini, Alessandra, additional, Callegari, Carlo, additional, Cautero, Giuseppe, additional, Dri, Carlo, additional, Di Fraia, Michele, additional, Prince, Kevin C., additional, Richter, Robert, additional, Sergo, Rudi, additional, Stebel, Luigi, additional, Devetta, Michele, additional, Faccialà, Davide, additional, Vozzi, Caterina, additional, Avaldi, Lorenzo, additional, Bolognesi, Paola, additional, Castrovilli, Mattea Carmen, additional, Catone, Daniele, additional, Coreno, Marcello, additional, Zuccaro, Fabio, additional, Bernes, Elisa, additional, Fronzoni, Giovanna, additional, Toffoli, Daniele, additional, and Ponzi, Aurora, additional

Published
2020
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12. The new FAST module: A portable and transparent add-on module for time-resolved investigations with commercial scanning probe microscopes

Author

European Commission, Agencia Estatal de Investigación (España), Generalitat de Catalunya, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), German Research Foundation, Alexander von Humboldt Foundation, Dri, Carlo, Panighel, Mirko, Tiemann, Daniel, Patera, Laerte L., Troiano, Giulia, Fukamori, Yves, Knoller, Fabian, Lechner, Barbara A.J., Cautero, Giuseppe, Giuressi, Dario, Comelli, Giovanni, Fraxedas, J., Africh, Cristina, Esch, Friedrich, European Commission, Agencia Estatal de Investigación (España), Generalitat de Catalunya, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), German Research Foundation, Alexander von Humboldt Foundation, Dri, Carlo, Panighel, Mirko, Tiemann, Daniel, Patera, Laerte L., Troiano, Giulia, Fukamori, Yves, Knoller, Fabian, Lechner, Barbara A.J., Cautero, Giuseppe, Giuressi, Dario, Comelli, Giovanni, Fraxedas, J., Africh, Cristina, and Esch, Friedrich

Abstract

Time resolution is one of the most severe limitations of scanning probe microscopies (SPMs), since the typical image acquisition times are in the order of several seconds or even few minutes. As a consequence, the characterization of dynamical processes occurring at surfaces (e.g. surface diffusion, film growth, self-assembly and chemical reactions) cannot be thoroughly addressed by conventional SPMs. To overcome this limitation, several years ago we developed a first prototype of the FAST module, an add-on instrument capable of driving a commercial scanning tunneling microscope (STM) at and beyond video rate frequencies. Here we report on a fully redesigned version of the FAST module, featuring improved performance and user experience, which can be used both with STMs and atomic force microscopes (AFMs), and offers additional capabilities such as an atom tracking mode. All the new features of the FAST module, including portability between different commercial instruments, are described in detail and practically demonstrated.

Published
2019

13. The new FAST module: A portable and transparent add-on module for time-resolved investigations with commercial scanning probe microscopes

Author

Dri, Carlo, primary, Panighel, Mirco, additional, Tiemann, Daniel, additional, Patera, Laerte L., additional, Troiano, Giulia, additional, Fukamori, Yves, additional, Knoller, Fabian, additional, Lechner, Barbara A.J., additional, Cautero, Giuseppe, additional, Giuressi, Dario, additional, Comelli, Giovanni, additional, Fraxedas, Jordi, additional, Africh, Cristina, additional, and Esch, Friedrich, additional

Published
2019
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16. Detectors for present and future light sources at Elettra

Author

Menk, Ralf Hendrik, primary, Antonelli, Matias, additional, Brajnik, Gabriele, additional, Bufon, Jernej, additional, Dri, Carlo, additional, Giuressi, Dario, additional, Gubertini, Alessandro, additional, Nichetti, Camilla, additional, Pinaroli, Giovanni, additional, Pittana, Paolo, additional, Schillani, Stefano, additional, Sergo, Rudi, additional, Stebel, Luigi, additional, and Cautero, Giuseppe, additional

Published
2019
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18. Detectors for Present and Future Light Sources at Elettra.

Author

Hendrik Menk, Ralf, Antonelli, Matias, Brajnik, Gabriele, Bufon, Jernej, Dri, Carlo, Giuressi, Dario, Gubertini, Alessandro, Nichetti, Camilla, Pinaroli, Giovanni, Pittana, Paolo, Schillani, Stefano, Sergo, Rudi, Stebel, Luigi, and Cautero, Giuseppe

Subjects
DETECTORS, SYNCHROTRONS, FREE electron lasers, QUANTUM efficiency, SYNCHROTRON radiation
Abstract

This work reports on the recent activities carried out by the Detector and Instrumentation Laboratory of Elettra Sincrotrone Trieste. Since both the Elettra synchrotron and the Fermi free electron laser are generating photons in the low to medium x-ray energy range from some eV to tenths of keV the activities of the detector and instrumentation laboratory focuses on spectroscopic and imaging photon detectors, which feature high quantum efficiency from below the carbon edge and are operated also in UHV environments. Special focus will be drawn on custom made monolithic and multi element silicon drift detectors for the Twinmic and the XRF beam line at Elettra. Regarding low energy imaging detectors the PERCIVAL CMOS (‘Pixelated Energy Resolving CMOS Imager, Versatile and Large’) will be discussed which is currently being developed by a collaboration of DESY, RAL, Elettra, PAL and DLS to address the need for this type of detectors for free electron lasers in the soft X-ray regime. The majorities of Elettra’s soft x-ray beam lines are employing fast and spatially resolving electron detectors and their associated readout electronics, which have been developed in-house and have been tailored to the specific needs of the respective beam line. In addition devices for in situ beam diagnostics and dose monitoring for synchrotron radiation and FEL beams have been developed and are operated on a daily basis. Moreover, some recent results in basic research on room temperature semiconductors will be discussed. It is noteworthy that Elettra Sincrotrone Trieste through its Industrial Liaison Office commercializes many of these devices and the associated read-out electronics. In this presentation an overview of these devices and their application to specific scientific applications will be given and in view of upgrade programs future directions will be discussed. [ABSTRACT FROM AUTHOR]

Published
2018
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19. Publisher Correction: Multi-orbital charge transfer at highly oriented organic/metal interfaces

Author

Zamborlini, Giovanni, primary, Lüftner, Daniel, additional, Feng, Zhijing, additional, Kollmann, Bernd, additional, Puschnig, Peter, additional, Dri, Carlo, additional, Panighel, Mirko, additional, Di Santo, Giovanni, additional, Goldoni, Andrea, additional, Comelli, Giovanni, additional, Jugovac, Matteo, additional, Feyer, Vitaliy, additional, and Schneider, Claus Michael, additional

Published
2017
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20. Tunability of the CO adsorption energy on a Ni/Cu surface: site change and coverage effects

Author

Vesselli, Erik, Rizzi, Michele, Furlan, Sara, Duan, Xiangmei, Monachino, Enrico, Dri, Carlo, Peronio, Angelo, Africh, Cristina, Lacovig, Paolo, Baldereschi, Alfonso, Comelli, Giovanni, Peressi, Maria, Vesselli, Erik, Rizzi, Michele, Furlan, Sara, Duan, Xiangmei, Monachino, Enrico, Dri, Carlo, Peronio, Angelo, Africh, Cristina, Lacovig, Paolo, Baldereschi, Alfonso, Comelli, Giovanni, and Peressi, Maria

Abstract

The adsorption energy of carbon monoxide on Ni ad-islands and ultra-thin films grown on the Cu(110) surface can be finely tuned via a complex interplay among diffusion, site change mechanisms, and coverage effects. The observed features of CO desorption can be explained in terms of migration of CO molecules from Cu to Ni islands, competition between bridge and on-top adsorption sites, and repulsive lateral adsorbate-adsorbate interactions. While the CO adsorption energy on clean Cu(110) is of the order of 0.5 eV, Ni-alloying allows for its controlled, continuous tunability in the 0.98-1.15 eV range with Ni coverage. Since CO is a fundamental reactant and intermediate in many heterogeneous catalytic (electro)-conversion reactions, insight into these aspects with atomic level detail provides useful information to potentially drive applicative developments. The tunability range of the CO adsorption energy that we measure is compatible with the already observed tuning of conversion rates by Ni doping of Cu single crystal catalysts for methanol synthesis from a CO2, CO, and H2 stream under ambient pressure conditions.

Published
2017

21. Effects of lattice expansion on the reactivity of a one-dimensional oxide

Author

Africh, Cristina, Kohler, Lukas, Corso, Martina, Esch, Friedrich, Dri, Carlo, Bucko, Tomas, Kresse, Georg, and Comelli, Giovanni

Subjects
Density functionals -- Usage, Oxidation-reduction reaction -- Analysis, Rhodium -- Chemical properties, Rhodium -- Atomic properties, Scanning tunneling microscopy -- Usage, Chemistry
Abstract

Scanning tunneling microscopy (STM) and density functional theory (DFT) calculations are used for characterizing the mechanism of the water formation reaction at the single-atom level on the O/Rh(110) surface, a prototype of a one-dimensional oxide. The reaction has produced a low-coverage, ordered patterning of the surface with residual oxygen at low temperatures and the lattice pattern formation is related to the segmentation of the oxide phase.

Published
2009

24. Electronic properties of the boroxine–gold interface: evidence of ultra-fast charge delocalization

Author

Toffoli, Daniele, primary, Stredansky, Matus, additional, Feng, Zhijing, additional, Balducci, Gabriele, additional, Furlan, Sara, additional, Stener, Mauro, additional, Ustunel, Hande, additional, Cvetko, Dean, additional, Kladnik, Gregor, additional, Morgante, Alberto, additional, Verdini, Alberto, additional, Dri, Carlo, additional, Comelli, Giovanni, additional, Fronzoni, Giovanna, additional, and Cossaro, Albano, additional

Published
2017
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26. Photoionization Dynamics of the Tetraoxo Complexes OsO4and RuO4

Author

Schio, Luca, Alagia, Michele, Toffoli, Daniele, Decleva, Piero, Richter, Robert, Schalk, Oliver, Thomas, Richard D., Mucke, Melanie, Salvador, Federico, Bertoch, Paolo, Benedetti, Davide, Dri, Carlo, Cautero, Giuseppe, Sergo, Rudi, Stebel, Luigi, Vivoda, Davide, and Stranges, Stefano

Abstract

The photoionization dynamics of OsO4and RuO4, chosen as model systems of small-size mononuclear heavy-metal complexes, has been theoretically studied by the time-dependent density functional theory (TDDFT). Accurate experimental measurements of photoionization dynamics as a benchmarking test for the theory are reported for the photoelectron asymmetry parameters of outer valence ionizations of OsO4, measured in the 17–90 eV photon energy range. The theoretical results are in good agreement with the available experimental data. The observed dynamical behavior of partial cross sections and asymmetry parameters has been related to both the coupling to the continuum of discrete excited states, giving strong modulations in the photon energy dependency, and the atomic composition of the initial ionized states, which determines the rate of decay of ionization probability for increasing excitation energies. Overall, an extensive analysis of the photoionization dynamics for valence and core orbitals is presented, showing good agreement with all the available experimental data. This provides confidence for the validity of the TDDFT approach in describing photoionization of heavy transition element compounds, with the perspective of being used for larger systems. Further experimental work is suggested for RuO4to gather evidence of the sensitivity of the theoretical method to the nature of the metal atom.

Published
2020
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27. Method for driving a scanning probe microscope at elevated scan frequencies

Author

Esch, Friedrich, Dri, Carlo, Comelli, Giovanni, Africh, Cristina, Spessot, Alessio, Esch, Friedrich, Dri, Carlo, Comelli, Giovanni, Africh, Cristina, and Spessot, Alessio

Subjects
scanning probe microscopy, scanning tunneling microscopy, mechanical resonances, piezoelectric, scanner, scanning probe microscopy, scanning tunneling microscopy, piezoelectric, mechanical resonances, scanner
Abstract

A method for operating a scanning probe microscope at elevated scan frequencies has a characterization stage of sweeping a plurality of excitation frequencies of the vertical displacement of the scanning element; measuring the value attained by the reading parameter at the excitation frequencies; and identifying plateau regions of the response spectrum of the reading parameter. The reading parameter variation is limited within a predetermined range over a predefined frequency interval, thereby defining corresponding fast scanning frequency windows in which the microscope assembly is sufficiently stable to yield a lateral resolution comparable to the one obtained during slow measurements. The measurement stage includes driving the scanning element along at least a scanning trajectory over the surface of the specimen at a frequency selected among the frequencies included in a fast scanning frequency window.

Published
2011

29. Effects of the Lattice Expansion on the Reactivity of a 1D Oxide

Author

AFRICH C, KÖHLER L, ESCH F, CORSO M, BUCKO T, KRESSE G, DRI, CARLO, COMELLI, GIOVANNI, Africh, C, Köhler, L, Esch, F, Corso, M, Dri, Carlo, Bucko, T, Kresse, G, and Comelli, Giovanni

Subjects
Scanning tunneling microscopy, 1D oxide, Reaction mechanism
Abstract

By means of scanning tunneling microscopy (STM) and density functional theory (DFT) calculations, we characterize at the single-atom level the mechanism of the water formation reaction on the (10 × 2)-O/Rh(110) surface, a prototype of a one-dimensional (1D) oxide where the lattice expansion and the segmentation of the surface play a fundamental role. When the reaction is imaged in the 238−263 K temperature range (35 s/image acquisition time), a peculiar comblike propagation mechanism for the reaction front is found. Fast STM measurements (33 ms/image) prove that this mechanism holds also at room temperature, being therefore an intrinsic characteristic of the reaction on the 1D oxide. DFT calculations explain the observed behavior as due to the interplay between the lattice expansion in the initial surface and its relaxation during the reaction that leads to varying configurations for the reactants.

Published
2009

31. Chemistry of the Methylamine Termination at a Gold Surface: From Autorecognition to Condensation

Author

Dri, Carlo, primary, Fronzoni, Giovanna, additional, Balducci, Gabriele, additional, Furlan, Sara, additional, Stener, Mauro, additional, Feng, Zhijing, additional, Comelli, Giovanni, additional, Castellarin-Cudia, Carla, additional, Cvetko, Dean, additional, Kladnik, Gregor, additional, Verdini, Alberto, additional, Floreano, Luca, additional, and Cossaro, Albano, additional

Published
2016
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37. Characterization and manipulation of single molecules and molecular complexes by low temperature scanning tunneling microscopy

Author

Dri, Carlo, Comelli, Giovanni, Africh, Cristina, and Esch, Friedrich

Subjects
organic molecules, hydrogen bond, surface patterning, molecular self-assembly, NANOTECNOLOGIE, low temperature, gold, ammonia, isomerization, ultra high vacuum, azobenzene derivatives, nitric oxide, FIS/03 FISICA DELLA MATERIA, scanning tunneling microscopy, platinum, molecular switches, coadsorption complexes
Abstract

2006/2007 The first part of this thesis work concerns the development of an ultra–high–vacuum experimental system, hosting a commercial Low Temperature Scanning Tunneling Microscope (LT-STM), that has been built for characterizing and manipulating single molecules and molecular complexes adsorbed on metal surfaces. The design from scratch, the commissioning and the performance tests of the various components of the system are presented. The preparation chamber that has been developed provides the fundamental surface preparation and analysis instruments, combining the STM analysis with other experimental techniques and allowing for easy setup of additional preparation/analysis instruments. The manipulator sample stage allows for a wide temperature range, needed for the preparation of a variety of surfaces to be investigated in the LT-STM. In the second part of this work, we present two examples of how molecules and molecular complexes can be studied and manipulated with the LT-STM technique. In the first example, within a collaboration established with the group of Dr. Leonhard Grill at the Freie Universität in Berlin, we have characterized an azobenzene derivative adsorbed on the Au(111) surface, a known molecular switch based on a trans–cis isomerization, which can be reversibly induced by the tip of the STM with controlled voltage pulses. We could show how the molecule–molecule interactions play a critical role in determining the switching abilities of the molecules between different self–assembled molecular islands, and how the molecule–substrate interaction can efficiently determine two different spatial periodicities of the switching molecules. In the second example, we have presented preliminary results regarding the characterization of the NH3-NO complex which forms on the Pt(111) surface, showing that by exploiting the manipulation and spectroscopic tools of the LT-STM, it will be possible to investigate at the atomic scale the properties of the hydrogen bond most likely involved the complex. La prima parte di questa tesi descrive lo sviluppo di un sistema sperimentale da ultra–alto–vuoto, dotato di un microscopio a scansione a effetto tunnel a bassa temperatura (LT-STM) disponibile in commercio. Il sistema è stato concepito e costruito per caratterizzare e manipolare singole molecole e complessi di molecole adsorbiti su superfici metalliche. Viene descritta la realizzazione del sistema sperimentale, a partire dalla fase di progettazione fino alla messa in opera e ai vari test di funzionamento che sono stati effettuati. La camera di preparazione che è stata costruita è provvista della strumentazione di base per la preparazione e l’analisi dei campioni di misura, e permette di integrare la tecnica STM con altre tecniche sperimentali e di installare in modo semplice e veloce nuovi strumenti. Il manipolatore è dotato di un sistema di riscaldamento campioni che permette di raggiungere un largo intervallo di temperature, necessario per la preparazione di svariati tipi di campioni da poter studiare tramite l’LT-STM. Nella seconda parte della tesi, vengono presentati due esempi di come, grazie alle potenzialità dell’LT-STM, è possibile caratterizzare e manipolare molecole e complessi di molecole. Nel primo dei due esempi, nell’ambito di una collaborazione con il gruppo del Dr. Leonhard Grill presso la Freie Universität a Berlino, è stato studiato sulla superficie (111) dell’oro il comportamento di un derivato dell’azobenzene, un “interruttore molecolare” basato sul processo di isomerizzazione trans–cis che può essere indotto in modo reversibile tramite impulsi di voltaggio dalla punta del microscopio STM. Si è dimostrato come le interazioni inter–molecolari giocano un ruolo fondamentale nel determinare se, all’interno di isole molecolari con diversa struttura, le molecole possono isomerizzare o meno; inoltre è stato scoperto che l’interazione delle molecole con il substrato può determinare l’ordinamento delle molecole in grado di isomerizzare, in strutture di periodicità definita all’interno delle isole molecolari. Nel secondo esempio che viene descritto, vengono presentati i risultati preliminari della caratterizzazione del complesso NH3-NO che si forma sulla superficie (111) del platino, e viene indicato come sarà possibile caratterizzare la natura dei legami idrogeno, che probabilmente stabilizzano il complesso, tramite le tecniche spettroscopiche e di manipolazione messe a disposizione dall’LT-STM. XX Ciclo 1980

Published
2008

42. Steering the Chemistry of Carbon Oxides on a NiCu Catalyst

Author

Vesselli, Erik, primary, Monachino, Enrico, additional, Rizzi, Michele, additional, Furlan, Sara, additional, Duan, Xiangmei, additional, Dri, Carlo, additional, Peronio, Angelo, additional, Africh, Cristina, additional, Lacovig, Paolo, additional, Baldereschi, Alfonso, additional, Comelli, Giovanni, additional, and Peressi, Maria, additional

Published
2013
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46. Experimental and Theoretical Investigation of the Restructuring Process Induced by CO at Near Ambient Pressure: Pt Nanoclusters on Graphene/Ir(111)

Author

Podda, Nicola, Corva, Manuel, Mohamed, Fatema, Feng, Zhijing, Dri, Carlo, Dvorák, Filip, Matolin, Vladimir, Comelli, Giovanni, Peressi, Maria, and Vesselli, Erik

Abstract

The adsorption of CO on Pt nanoclusters grown in a regular array on a template provided by the graphene/Ir(111) Moiré was investigated by means of infrared-visible sum frequency generation vibronic spectroscopy, scanning tunneling microscopy, X-ray photoelectron spectroscopy from ultrahigh vacuum to near-ambient pressure, and ab initiosimulations. Both terminally and bridge bonded CO species populate nonequivalent sites of the clusters, spanning from first to second-layer terraces to borders and edges, depending on the particle size and morphology and on the adsorption conditions. By combining experimental information and the results of the simulations, we observe a significant restructuring of the clusters. Additionally, above room temperature and at 0.1 mbar, Pt clusters catalyze the spillover of CO to the underlying graphene/Ir(111) interface.

Published
2017
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