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30 results on '"Angot, T."'

1. Flux dependence of helium retention in clean W(110): Experimental evidence for He self-trapping

Author

Dunand, A., Minissale, M., Angot, T., and Bisson, R.

Subjects
Physics - Chemical Physics
Abstract

Helium (He) retention in tungsten (W) is a concern in fusion reactors since it could be detrimental to plasma facing components performance and influence the fusion fuel balance. He being not soluble in W, it tends to agglomerate on preexisting defects (vacancy, grain boundary), but it could in theory also self-trap (be immobilized on a non-preexisting vacancy) through the emission of a vacancy/self-interstitial W pair in the vicinity of a Hen interstitial cluster. In the present study, we prepared a pure single crystal W(110) sample with a clean surface in order to evidence the self-trapping of He in the W bulk at a sample temperature of 300 K and for a constant fluence of 2.0x10$^{21}$ He$^+$.m$^{-2}$. At a He$^+$ kinetic energy of 130 eV and a flux of 0.3x10$^{17}$ He$^+$.m$^{-2}$.s$^{-1}$, we only observed a small He desorption peak below 600 K. Rising the ion flux to 0.7x10$^{17}$ He$^+$.m$^{-2}$.s$^{-1}$, we observed the sudden appearance of two desorption peaks at 950 K and 1700 K. For the highest flux studied in this work, 5.0x10$^{17}$ He$^+$.m$^{-2}$.s$^{-1}$, an additional desorption peak at 1800 K and a desorption shoulder at 1900 K are observed. The temperature position of these He desorption peaks are consistent with the density functional theory literature and points to the occurrence of self-trapping once the 0.7x10$^{17}$ He$^+$.m$^{-2}$.s$^{-1}$ flux is attained at 300 K and to the possible realization of trap-mutation for the flux of 5.0x10$^{17}$ He$^+$.m$^{-2}$.s$^{-1}$. The present set of results should be used to constrain the development of He retention and He bubbles growth models based on ab initio quantities.

Published
2022
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2. Kagome silicene: a novel exotic form of two-dimensional epitaxial silicon

Author

Sassa, Y., Johansson, F. O. L., Lindblad, A., Yazdi, M. G., Simonov, K., Weissenrieder, J., Muntwiler, M., Iyikanat, F., Sahin, H., Angot, T., Salomon, E., and Lay, G. Le

Subjects
Condensed Matter - Materials Science
Abstract

Since the discovery of graphene, intensive efforts have been made in search of novel two-dimensional (2D) materials. Decreasing the materials dimensionality to their ultimate thinness is a promising route to unveil new physical phenomena, and potentially improve the performance of devices. Among recent 2D materials, analogs of graphene, the group IV elements have attracted much attention for their unexpected and tunable physical properties. Depending on the growth conditions and substrates, several structures of silicene, germanene, and stanene can be formed. Here, we report the synthesis of a Kagome lattice of silicene on aluminum (111) substrates. We provide evidence of such an exotic 2D Si allotrope through scanning tunneling microscopy (STM) observations, high-resolution core-level (CL) and angle-resolved photoelectron spectroscopy (ARPES) measurements, along with Density Functional Theory calculations., Comment: 13 pages, 6 figures

Published
2020
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3. Diagnostics of low-pressure hydrogen discharge created in a 13.56 MHz RF plasma reactor

Author

Krištof, J, Annušová, A, Anguš, M, Veis, P., Yang, X, Angot, T, Roubin, P., and Cartry, G.

Subjects
Physics - Plasma Physics
Abstract

A 13.56 MHz RF discharge in hydrogen was studied within the pressure range of 1-17 10 Pa, and at power range of 400-1000 W. The electron energy distribution function and 18 electron density were measured by a Langmuir probe. The gas temperature was determined by 19 the Fulcher-$\alpha$ system in pure H2, and by the second positive system of nitrogen using N2 as the 20 probing gas. The gas temperature was constant and equal to 450 $\pm$ 50 K in the Capacitively 21 Coupled Plasma mode (CCP), and it was increasing with pressure and power in the Inductively 22 Coupled Plasma mode (ICP). Also the vibrational temperature of ground state of hydrogen 23 molecules was determined to be around 3100 and 2000 $\pm$ 500 K in ICP and CCP mode, 24 respectively. The concentration of atomic hydrogen was determined by means of actinometry, 25 either by using Ar (5 %) as the probing gas, or by using H2 as the actinometer in pure hydrogen 26 (Q1 rotational line of Fulcher-$\alpha$ system) The concentration of hydrogen density was increasing 27 with pressure in both modes, but with a dissociation degree slightly higher in the ICP mode (a 28 factor 2). 29 30 Submitted to Physica Scripta 31

Published
2019
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8. Latest experimental and theoretical advances in the production of negative ions in caesium-free plasmas

Author

Taccogna, F., Bechu, S., Aanesland, A., Agostinetti, P., Agnello, R., Aleiferis, S., Angot, T., Antoni, V., Bacal, M., Barbisan, M., Bentounes, J., Bès, A., Capitelli, M., Cartry, G., Cavenago, M., Celiberto, R., Chitarin, G., Delogu, R., De Lorenzi, A., Esposito, F., Fadone, M., Ferron, N., Fubiani, G., Furno, I., Gavilan, L., Guittienne, P., Howling, A., Jacquier, R., Laricchiuta, A., Layet, J. M., Lemaire, J. L., Longo, S., Maurice, B., Minelli, P., Minissale, M., Mitrou, M., Moussaoui, R., Pimazzoni, A., Poggi, C., Rafalskyi, D., Salomon, E., Sartori, E., Sasao, M., Serianni, G., Spada, E., Suweis, S., Svarnas, P., Tahri, L., Ugoletti, M., Variale, V., and Veltri, P.

Published
2021
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18. Publisher's Note: "Laser temperature programmed desorption: A flexible technique to study ion-surface interaction" [Rev. Sci. Instrum. 95, 033004 (2024)].

Author

Minissale, M., Dunand, A., Hiret, P., Faure, J.-B., Grisolia, C., Angot, T., Gallais, L., and Bisson, R.

Subjects
DESORPTION, LASERS, PUBLISHING, SCIENTIFIC apparatus & instruments, TEMPERATURE
Abstract

This article, titled "Laser temperature programmed desorption: A flexible technique to study ion-surface interaction," was published in the Review of Scientific Instruments. It was originally published online on March 7, 2024, but was missing information from the Acknowledgments section. The missing information has since been reinstated, acknowledging that the work was carried out within the framework of the French Federation for Magnetic Fusion Studies (FR-FCM) and received funding from Aix-Marseille University and the ANR. AIP Publishing has apologized for the error and corrected all online versions of the article on March 8, 2024. The authors of the article are M. Minissale, A. Dunand, P. Hiret, J.-B. Faure, C. Grisolia, T. Angot, L. Gallais, and R. Bisson. [Extracted from the article]

Published
2024
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19. Fundamentals and functionalities of silicene, germanene, and stanene

Author

Ezawa M., Salomon E., De Padova P., Solonenko D., Vogt P., Davila M.E., Molle A., Angot T., and Le Lay G.

Subjects
silicene, germanene, stanene
Abstract

Two-dimensional elemental topological insulators including silicene, germanene and stanene are currently the hottest topics in condensed matter physics. We first review the recent progress on electronic and topological properties of their monolayers from a fundamental viewpoint. Next, we describe their experimental realizations by epitaxial growth and their actual physical properties. We start with the description of the topological nature of generic Dirac systems and then apply it to silicene by introducing the spin and valley degrees of freedom. Based on them, we classify all topological insulators in the general honeycomb system. We discuss topological electronics based on honeycomb systems. We introduce the topological Kirchhoff law, which is a conservation law of topological edge states. A field effect topological transistor is proposed based on the topological edge states. We show that the conductance is quantized even in the presence of random distributed impurities. Monolayer topological insulators will be a key for future topological electronics and spin-valleytronics. The outstanding example of the realization of such monolayer Si, Ge and Sn novel artificial allotropes is the canonical 3 3 reconstructed epitaxial silicene phase grown in situ under ultra-high vacuum on the silver (111) surface. Its realization in 2012 has preceded the synthesis of germanene, followed by that of stanene, respectively on Au(111) and Bi2Te3 substrates. Further growth of Si and Ge over monolayer epitaxial silicene and germanene leads to layered thin films displaying Dirac fermion characteristics. Amazingly, Si deposition onto Ag(110) templates yields massively parallel, pentasilicene-like nanoribbons, a novel form of one-dimensional silicon. Field Effect Transistors have been already fabricated both with single and multi-layer silicene channels, clearly demonstrating potential applications in electronics of silicene and such related materials, which are directly compatible with the current, ubiquitous, Si-based technology. Finally, enticing prospects are outlined.

Published
2018

21. Plasma–wall interaction studies within the EUROfusion consortium: progress on plasma-facing components development and qualification

Author

Brezinsek, S., primary, Coenen, J.W., additional, Schwarz-Selinger, T., additional, Schmid, K., additional, Kirschner, A., additional, Hakola, A., additional, Tabares, F.L., additional, van der Meiden, H.J., additional, Mayoral, M.-L., additional, Reinhart, M., additional, Tsitrone, E., additional, Ahlgren, T., additional, Aints, M., additional, Airila, M., additional, Almaviva, S., additional, Alves, E., additional, Angot, T., additional, Anita, V., additional, Arredondo Parra, R., additional, Aumayr, F., additional, Balden, M., additional, Bauer, J., additional, Ben Yaala, M., additional, Berger, B.M., additional, Bisson, R., additional, Björkas, C., additional, Bogdanovic Radovic, I., additional, Borodin, D., additional, Bucalossi, J., additional, Butikova, J., additional, Butoi, B., additional, Čadež, I., additional, Caniello, R., additional, Caneve, L., additional, Cartry, G., additional, Catarino, N., additional, Čekada, M., additional, Ciraolo, G., additional, Ciupinski, L., additional, Colao, F., additional, Corre, Y., additional, Costin, C., additional, Craciunescu, T., additional, Cremona, A., additional, De Angeli, M., additional, de Castro, A., additional, Dejarnac, R., additional, Dellasega, D., additional, Dinca, P., additional, Dittmar, T., additional, Dobrea, C., additional, Hansen, P., additional, Drenik, A., additional, Eich, T., additional, Elgeti, S., additional, Falie, D., additional, Fedorczak, N., additional, Ferro, Y., additional, Fornal, T., additional, Fortuna-Zalesna, E., additional, Gao, L., additional, Gasior, P., additional, Gherendi, M., additional, Ghezzi, F., additional, Gosar, Ž., additional, Greuner, H., additional, Grigore, E., additional, Grisolia, C., additional, Groth, M., additional, Gruca, M., additional, Grzonka, J., additional, Gunn, J.P., additional, Hassouni, K., additional, Heinola, K., additional, Höschen, T., additional, Huber, S., additional, Jacob, W., additional, Jepu, I., additional, Jiang, X., additional, Jogi, I., additional, Kaiser, A., additional, Karhunen, J., additional, Kelemen, M., additional, Köppen, M., additional, Koslowski, H.R., additional, Kreter, A., additional, Kubkowska, M., additional, Laan, M., additional, Laguardia, L., additional, Lahtinen, A., additional, Lasa, A., additional, Lazic, V., additional, Lemahieu, N., additional, Likonen, J., additional, Linke, J., additional, Litnovsky, A., additional, Linsmeier, Ch., additional, Loewenhoff, T., additional, Lungu, C., additional, Lungu, M., additional, Maddaluno, G., additional, Maier, H., additional, Makkonen, T., additional, Manhard, A., additional, Marandet, Y., additional, Markelj, S., additional, Marot, L., additional, Martin, C., additional, Martin-Rojo, A.B., additional, Martynova, Y., additional, Mateus, R., additional, Matveev, D., additional, Mayer, M., additional, Meisl, G., additional, Mellet, N., additional, Michau, A., additional, Miettunen, J., additional, Möller, S., additional, Morgan, T.W., additional, Mougenot, J., additional, Mozetič, M., additional, Nemanič, V., additional, Neu, R., additional, Nordlund, K., additional, Oberkofler, M., additional, Oyarzabal, E., additional, Panjan, M., additional, Pardanaud, C., additional, Paris, P., additional, Passoni, M., additional, Pegourie, B., additional, Pelicon, P., additional, Petersson, P., additional, Piip, K., additional, Pintsuk, G., additional, Pompilian, G.O., additional, Popa, G., additional, Porosnicu, C., additional, Primc, G., additional, Probst, M., additional, Räisänen, J., additional, Rasinski, M., additional, Ratynskaia, S., additional, Reiser, D., additional, Ricci, D., additional, Richou, M., additional, Riesch, J., additional, Riva, G., additional, Rosinski, M., additional, Roubin, P., additional, Rubel, M., additional, Ruset, C., additional, Safi, E., additional, Sergienko, G., additional, Siketic, Z., additional, Sima, A., additional, Spilker, B., additional, Stadlmayr, R., additional, Steudel, I., additional, Ström, P., additional, Tadic, T., additional, Tafalla, D., additional, Tale, I., additional, Terentyev, D., additional, Terra, A., additional, Tiron, V., additional, Tiseanu, I., additional, Tolias, P., additional, Tskhakaya, D., additional, Uccello, A., additional, Unterberg, B., additional, Uytdenhoven, I., additional, Vassallo, E., additional, Vavpetič, P., additional, Veis, P., additional, Velicu, I.L., additional, Vernimmen, J.W.M., additional, Voitkans, A., additional, von Toussaint, U., additional, Weckmann, A., additional, Wirtz, M., additional, Založnik, A., additional, and Zaplotnik, R., additional

Published
2017
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22. Retention and release of hydrogen isotopes in tungsten plasma-facing components: the role of grain boundaries and the native oxide layer from a joint experiment-simulation integrated approach

Author

Hodille, E.A., primary, Ghiorghiu, F., additional, Addab, Y., additional, Založnik, A., additional, Minissale, M., additional, Piazza, Z., additional, Martin, C., additional, Angot, T., additional, Gallais, L., additional, Barthe, M.-F., additional, Becquart, C.S., additional, Markelj, S., additional, Mougenot, J., additional, Grisolia, C., additional, and Bisson, R., additional

Published
2017
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26. Correlation between Charge Transfer and Adsorption Site in CoPc Overlayers Adsorbed on Ag(100)

Author

Gregor Kladnik, Thierry Angot, Dean Cvetko, Alberto Verdini, D. Beato-Medina, Luca Floreano, Eric Salomon, A. Cossaro, Salomon, E., Beato-Medina, D., Verdini, A., Cossaro, A., Cvetko, D., Kladnik, G., Floreano, L., and Angot, T.

Subjects
Correlation between Charge Transfer and Adsorption Site in CoPc Over layers Adsorbed on Ag(100), Chemistry, Superlattice, Electron energy loss spectroscopy, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, law.invention, Condensed Matter::Materials Science, Crystallography, General Energy, Adsorption, Electron diffraction, law, Chemical physics, Atom, XPS, Molecule, CoPc, Physics::Chemical Physics, Physical and Theoretical Chemistry, Scanning tunneling microscope, Superstructure (condensed matter)
Abstract

In this paper we investigate the local adsorption geometry of CoPc films adsorbed on a Ag(100) surface and its effect on the molecule-substrate interactions. Using high-resolution electron energy loss spectroscopy we demonstrate that the charge-transfer mechanism at the organic-metal interface depends on the structural properties of the CoPc film. We discuss these findings in terms of the molecular adsorption sites, as determined by X-ray photoelectron diffraction measurements and multiple scattering simulations. We show that the distance between the central Co atom and the topmost Ag layer is of the order of 0.3 nm. In addition, we demonstrate that the Co Pc molecules adsorb on different atomic sites depending on the superlattice symmetry, as varied by changing the coverage. This is further confirmed by low-energy electron diffraction and scanning tunneling microscopy measurements, emphasizing that, depending on the molecular superstructure adopted by the molecules, there are one or two molecules per unit cell.

Published
2015

27. Patterned formation of enolate functional groups on the graphene basal plane.

Author

Cassidy A, Pedersen S, Bluhm H, Calisti V, Angot T, Salomon E, Bisson R, and Hornekær L

Abstract

Chemical functionalization of graphene is one method pursued to engineer new properties into a graphene sheet. Graphene oxide is the most commonly used chemical derivative of graphene. Here we present experimental evidence for the formation of enolate moieties when oxygen atoms are added to the graphene basal plane. The exotic functional groups are stabilized by simultaneous bond formation between the graphene sheet and the underlying Ir(111) substrate. Scanning tunneling microscopy images demonstrate the patterned nature of C-O bond formation and X-ray photoelectron spectroscopy and high-resolution electron energy loss spectroscopy are used to characterize the enolate moiety. The results present a new mechanism for the formation of patterned graphene oxide and provide evidence of a functional group rarely considered for graphene oxide materials.

Published
2018
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28. The Orientation of Silver Surfaces Drives the Reactivity and the Selectivity in Homo-Coupling Reactions.

Author

Kalashnyk N, Salomon E, Mun SH, Jung J, Giovanelli L, Angot T, Dumur F, Gigmes D, and Clair S

Abstract

Original reaction pathways can be explored in the on-surface synthesis approach where small aromatic precursors are confined to the surface of single crystal metals. The bis-indanedione molecule reacted with itself on silver surfaces in different ways, through a Knoevenagel reaction or an oxidative coupling, leading to the formation of a variety of new molecular compounds and covalently-linked 1D or 2D networks. Noteworthy, original reaction products were obtained that cannot be synthesized in traditional solvent-based chemistry. The lowest activation temperature for the homo-coupling reactions was found on the Ag(111) surface. The Ag(110) was highly selective in terms of coupling reaction type, while on Ag(100) the temperature could finely control the selectivity. The on-surface synthesis approach is shown here to be particularly efficient to produce original compounds in mild conditions, using activation temperatures as low as 200 °C. The different structures were characterized by scanning tunnelling microscopy (STM) together with X-ray photoelectron emission spectroscopy (XPS) and high-resolution electron energy loss spectroscopy (HREELS)., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Published
2018
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29. Exciting H 2 Molecules for Graphene Functionalization.

Author

Kyhl L, Bisson R, Balog R, Groves MN, Kolsbjerg EL, Cassidy AM, Jørgensen JH, Halkjær S, Miwa JA, Grubišić Čabo A, Angot T, Hofmann P, Arman MA, Urpelainen S, Lacovig P, Bignardi L, Bluhm H, Knudsen J, Hammer B, and Hornekaer L

Abstract

Hydrogen functionalization of graphene by exposure to vibrationally excited H 2 molecules is investigated by combined scanning tunneling microscopy, high-resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy measurements, and density functional theory calculations. The measurements reveal that vibrationally excited H 2 molecules dissociatively adsorb on graphene on Ir(111) resulting in nanopatterned hydrogen functionalization structures. Calculations demonstrate that the presence of the Ir surface below the graphene lowers the H 2 dissociative adsorption barrier and allows for the adsorption reaction at energies well below the dissociation threshold of the H-H bond. The first reacting H 2 molecule must contain considerable vibrational energy to overcome the dissociative adsorption barrier. However, this initial adsorption further activates the surface resulting in reduced barriers for dissociative adsorption of subsequent H 2 molecules. This enables functionalization by H 2 molecules with lower vibrational energy, yielding an avalanche effect for the hydrogenation reaction. These results provide an example of a catalytically active graphene-coated surface and additionally set the stage for a re-interpretation of previous experimental work involving elevated H 2 background gas pressures in the presence of hot filaments.

Published
2018
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30. On-surface synthesis of aligned functional nanoribbons monitored by scanning tunnelling microscopy and vibrational spectroscopy.

Author

Kalashnyk N, Mouhat K, Oh J, Jung J, Xie Y, Salomon E, Angot T, Dumur F, Gigmes D, and Clair S

Abstract

In the blooming field of on-surface synthesis, molecular building blocks are designed to self-assemble and covalently couple directly on a well-defined surface, thus allowing the exploration of unusual reaction pathways and the production of specific compounds in mild conditions. Here we report on the creation of functionalized organic nanoribbons on the Ag(110) surface. C-H bond activation and homo-coupling of the precursors is achieved upon thermal activation. The anisotropic substrate acts as an efficient template fostering the alignment of the nanoribbons, up to the full monolayer regime. The length of the nanoribbons can be sequentially increased by controlling the annealing temperature, from dimers to a maximum length of about 10 nm, limited by epitaxial stress. The different structures are characterized by room-temperature scanning tunnelling microscopy. Distinct signatures of the covalent coupling are measured with high-resolution electron energy loss spectroscopy, as supported by density functional theory calculations.

Published
2017
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