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183 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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3. 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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4. 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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9. Raman study of CFC tiles extracted from the toroidal pump limiter of Tore Supra

Author

Pardanaud, Cedric, Giacometti, G., Martin, C., Ruffe, R., Angot, T., Aréou, E., Pégourié, B., Tsitrone, E., Dittmar, T., Hopf, C., Jacob, W., Schwarz-Selinger, T., and Roubin, P.

Subjects
Condensed Matter - Materials Science, Physics - Chemical Physics
Abstract

The structure of six tiles extracted from the erosion and deposition zones (thin and thick deposition) of the Tore Supra toroidal pump limiter (TPL) have been analysed in the framework of the DITS campaign using micro-Raman spectroscopy. This post-mortem analysis gives information on both carbon structure and D content. We have found that the carbon structure is most often similar to that of plasma-deposited hard amorphous carbon layers. The role of the surface temperature during the discharge in the D content is investigated: in all locations where the temperature does not reach more than 500{\degree}C the D content seems to be roughly uniform with D/D+C \approx 20%.

Published
2013
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10. Raman micro-spectroscopy as a tool to measure the absorption coefficient and the erosion rate of hydrogenated amorphous carbon films heat-treated under hydrogen bombardment

Author

Pardanaud, Cedric, Aréou, E., Martin, C., Ruffe, R., Angot, T., Roubin, P., Hopf, C., Schwarz-Selinger, T., and Jacob, W.

Subjects
Condensed Matter - Materials Science, Physics - Chemical Physics
Abstract

We present a fast and simple way to determine the erosion rate and absorption coefficient of hydrogenated amorphous carbon films exposed to a hydrogen atomic source based on ex-situ Raman micro-spectroscopy. Results are compared to ellipsometry measurement. The method is applied to films eroded at different temperatures. A maximum of the erosion rate is found at ~ 450 {\degree}C in agreement with previous results. This technique is suitable for future quantitative studies on the erosion of thin carbonaceous films, especially of interest for plasma wall interactions occurring in thermonuclear fusion devices.

Published
2013
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11. On the interpretation of valence band photoemission spectra at organic-metal interfaces

Author

Giovanelli, L., Bocquet, F. C., Amsalem, P., Lee, H. -L., Abel, M., Clair, S., Koudia, M., Faury, T., Petaccia, L., Topwal, D., Salomon, E., Angot, T., Cafolla, A. A., Koch, N., Porte, L., Goldoni, A., and Themlin, J. -M.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Physics - Chemical Physics
Abstract

Adsorption of organic molecules on well-oriented single crystal coinage metal surfaces fundamentally affects the energy distribution curve of ultra-violet photoelectron spectroscopy spectra. New features not present in the spectrum of the pristine metal can be assigned as "interface states" having some degree of molecule-substrate hybridization. Here it is shown that interface states having molecular orbital character can easily be identified at low binding energy as isolated features above the featureless substrate sp-plateau. On the other hand much care must be taken in assigning adsorbate-induced features when these lie within the d-band spectral region of the substrate. In fact, features often interpreted as characteristic of the molecule-substrate interaction may actually arise from substrate photoelectrons scattered by the adsorbates. This phenomenon is illustrated through a series of examples of noble-metal single-crystal surfaces covered by monolayers of large pi-conjugated organic molecules.

Published
2012
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12. 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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30. 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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31. 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

34. Hydrogen-graphite interaction: Experimental evidences of an adsorption barrier.

Author

Aréou, E., Cartry, G., Layet, J.-M., and Angot, T.

Subjects
ADSORPTION (Chemistry), SURFACE chemistry, ELECTRON energy loss spectroscopy, ATOM-atom collisions, HYDROGEN, GRAPHITE
Abstract

The interaction of H atoms having relatively low average kinetic energy (∼0.025 eV) with both perfectly clean and D-covered HOPG surfaces is investigated using high resolution electron energy loss spectroscopy. From this study we confirm, in a controlled fashion, the presence of the theoretically predicted adsorption barrier since no adsorption is detected for such H atoms on HOPG. Moreover, we demonstrate that the exposure of a D saturated HOPG surface to these H atoms results in the complete removal of adatoms, with no further adsorption despite the prediction of the adsorption barrier to vanish for H dimers in para configuration. Therefore, the recombinative abstraction mechanism which competes with the adsorption process is more efficient. [ABSTRACT FROM AUTHOR]

Published
2011
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35. Ordered phthalocyanine superstructures on Ag(110).

Author

Palmgren, P., Angot, T., Nlebedim, C. I., Layet, J.-M., Le Lay, G., and Göthelid, M.

Subjects
*PHTHALOCYANINES, *MOLECULAR electronics, *SYNCHROTRONS, *ELECTRON diffraction, *SPECTRUM analysis, *MOLECULAR orbitals, *MOLECULAR spectroscopy
Abstract

Organic-metal interfaces, in particular, self-assembling systems, are interesting in the field of molecular electronics. In this study, we have investigated the formation of the Ag(110)-iron phthalocyanine (FePc) interface in a coverage range of less than 1 and up to 2 ML using synchrotron based photoelectron spectroscopy and low energy electron diffraction. As-deposited FePc forms a densely packed first layer exhibiting a 3×2/c(6×2) symmetry. Upon thermal treatment the order at the interface is modified depending on the initial FePc coverage, resulting in less densely packed but still ordered superstructures. The first monolayer is relatively strongly bound to the substrate, leading to the formation of an interface state just below the Fermi level. The highest occupied molecular orbital of FePc in the second layer is found at 1 eV higher binding energy compared to the interface state. [ABSTRACT FROM AUTHOR]

Published
2008
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36. Hydrogen adsorption on graphite (0001) surface: A combined spectroscopy–density-functional-theory study.

Author

Allouche, A., Ferro, Y., Angot, T., Thomas, C., and Layet, J. -M.

Subjects
ADSORPTION (Chemistry), HYDROGEN, SPECTRUM analysis, DENSITY functionals, CARBON, THERMAL desorption
Abstract

The adsorption of H/D atoms on the graphite (0001) surface is investigated by means of both high-resolution electron-energy loss spectroscopy (HREELS) and periodic first-principle density-functional theory. The two methods converge towards two modes of adsorption: adsorption in clusters of about four hydrogen atoms and adsorption in pairs of atoms on contiguous carbon sites. The desorption energies estimated from the calculated dissociation energies range from 8 to 185 kJ mol-1 leading to an estimated surface coverage at saturations of 30–44 at. %. These results are compared with previous thermal desorption spectroscopy results. New HREEL signal assignments are proposed based on quantum calculations. [ABSTRACT FROM AUTHOR]

Published
2005
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40. 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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41. 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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47. Etching of silicon nanowires on Ag(110) by atomic hydrogen

Author

Salomon, E., Angot, T., Thomas, C., Layet, J. M., Palmgren, Pål, Nlebedim, C. I., Göthelid, Mats, Salomon, E., Angot, T., Thomas, C., Layet, J. M., Palmgren, Pål, Nlebedim, C. I., and Göthelid, Mats

Abstract

Scanning Tunnelling Microscopy, High Resolution Electron Energy Loss Spectroscopy and High Resolution X-Ray Photoelectron Spectroscopy have been used to study the adsorption of atomic hydrogen onto Si nanowires grown on Ag(1 1 0). We demonstrate that the hydrogen strongly interacts with the Si nanowires modifying their structural and electronic properties. Hydrogen atoms etch the Si nanowires and eventually lead to their complete removal from the Ag(1 1 0) surface., QC 20100525

Published
2009
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48. Strong interactions in dye-sensitized interfaces

Author

Palmgren, P., Nilson, K., Yu, S., Hennies, F., Angot, T., Nlebedim, C. I., Layet, J. -M., Le Lay, G., Goethlid, M., Palmgren, P., Nilson, K., Yu, S., Hennies, F., Angot, T., Nlebedim, C. I., Layet, J. -M., Le Lay, G., and Goethlid, M.

Abstract

Phthalocyanines (Pcs) are capable of converting sunlight into electric energy when adsorbed on TiO2 in a dye-sensitized solar cell. Of special interest in this type of cell is the energy level alignment as well as how molecules adsorb on the surface as it determines the output of the cell. We investigated the FePc-TiO2(110) interface using scanning tunneling microscopy, synchrotron-based photoelectron spectroscopy, and X-ray absorption spectroscopy. We found a strong coupling of the first-layer FePc to the substrate resulting in an alteration of the electronic structure and charge transfer from the molecules. The FePc in the second layer is not severely affected by the bonding to the surface and has bulk-like electronic properties. The growth of FePc thin films proceeds in a layer plus island mode, and the molecular plane is parallel to the surface. The energy level alignment at the interface is determined, and the lowest unoccupied molecular orbital is found above the conduction band minimum of the oxide substrate.

Published
2008
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49. Ordered phthalocyanine superstructures on Ag(110)

Author

Palmgren, Pål, Angot, T., Nlebedim, Cajetan Ikenna, Layet, J. -M, Le Lay, G., Göthelid, Mats, Palmgren, Pål, Angot, T., Nlebedim, Cajetan Ikenna, Layet, J. -M, Le Lay, G., and Göthelid, Mats

Abstract

Organic-metal interfaces, in particular, self-assembling systems, are interesting in the field of molecular electronics. In this study, we have investigated the formation of the Ag(110)-iron phthalocyanine (FePc) interface in a coverage range of less than 1 and up to 2 ML using synchrotron based photoelectron spectroscopy and low energy electron diffraction. As-deposited FePc forms a densely packed first layer exhibiting a 3x2/c(6x2) symmetry. Upon thermal treatment the order at the interface is modified depending on the initial FePc coverage, resulting in less densely packed but still ordered superstructures. The first monolayer is relatively strongly bound to the substrate, leading to the formation of an interface state just below the Fermi level. The highest occupied molecular orbital of FePc in the second layer is found at 1 eV higher binding energy compared to the interface state., QC 20111108

Published
2008
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