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Hong Z, Diao Q, Xu W, Yuan Q, Yang J, Li Z, Jiang Y, Zhang C, Zhang D, Liu F, Zhang X, Liu P, Tao Y, Sheng W, Li M, Zhao Y. A magnetically controlled chemical-mechanical polishing (MC-CMP) approach for fabricating channel-cut silicon crystal optics for the High Energy Photon Source. JOURNAL OF SYNCHROTRON RADIATION 2023; 30:84-89. [PMID: 36601929 PMCID: PMC9814062 DOI: 10.1107/s1600577522011122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 11/21/2022] [Indexed: 06/17/2023]
Abstract
Crystal monochromators are indispensable optical components for the majority of beamlines at synchrotron radiation facilities. Channel-cut monochromators are sometimes chosen to filter monochromatic X-ray beams by virtue of their ultrahigh angular stability. Nevertheless, high-accuracy polishing on the inner diffracting surfaces remains challenging, thus hampering their performance in preserving the coherence or wavefront of the photon beam. Herein, a magnetically controlled chemical-mechanical polishing (MC-CMP) approach has been successfully developed for fine polishing of the inner surfaces of channel-cut crystals. This MC-CMP process relieves the constraints of narrow working space dictated by small offset requirements and achieves near-perfect polishing on the surface of the crystals. Using this method, a high-quality surface with roughness of 0.614 nm (root mean square, r.m.s.) is obtained in a channel-cut crystal with 7 mm gap designed for beamlines at the High Energy Photon Source, a fourth-generation synchrotron radiation source under construction. On-line X-ray topography and rocking-curve measurements indicate that the stress residual layer on the crystal surface was removed. Firstly, the measured rocking-curve width is in good agreement with the theoretical value. Secondly, the peak reflectivity is very close to theoretical values. Thirdly, topographic images of the optics after polishing were uniform without any speckle or scratches. Only a nearly 2.5 nm-thick SiO2 layer was observed on the perfect crystalline matrix from high-resolution transmission electron microscopy photographs, indicating that the structure of the bulk material is defect- and dislocation-free. Future development of MC-CMP is promising for fabricating wavefront-preserving and ultra-stable channel-cut monochromators, which are crucial to exploit the merits of fourth-generation synchrotron radiation sources or hard X-ray free-electron lasers.
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Affiliation(s)
- Zhen Hong
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Qianshun Diao
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Wei Xu
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Qingxi Yuan
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Junliang Yang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Zhongliang Li
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201800, People’s Republic of China
| | - Yongcheng Jiang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Changrui Zhang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Dongni Zhang
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Fang Liu
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Xiaowei Zhang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Peng Liu
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Ye Tao
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Weifan Sheng
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Ming Li
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Yidong Zhao
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
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Double-crowned 2D semiconductor nanoplatelets with bicolor power-tunable emission. Nat Commun 2022; 13:5094. [PMID: 36042249 PMCID: PMC9427944 DOI: 10.1038/s41467-022-32713-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 08/10/2022] [Indexed: 11/29/2022] Open
Abstract
Nanocrystals (NCs) are now established building blocks for optoelectronics and their use as down converters for large gamut displays has been their first mass market. NC integration relies on a combination of green and red NCs into a blend, which rises post-growth formulation issues. A careful engineering of the NCs may enable dual emissions from a single NC population which violates Kasha’s rule, which stipulates that emission should occur at the band edge. Thus, in addition to an attentive control of band alignment to obtain green and red signals, non-radiative decay paths also have to be carefully slowed down to enable emission away from the ground state. Here, we demonstrate that core/crown/crown 2D nanoplatelets (NPLs), made of CdSe/CdTe/CdSe, can combine a large volume and a type-II band alignment enabling simultaneously red and narrow green emissions. Moreover, we demonstrate that the ratio of the two emissions can be tuned by the incident power, which results in a saturation of the red emission due to non-radiative Auger recombination that affects this emission much stronger than the green one. Finally, we also show that dual-color, power tunable, emission can be obtained through an electrical excitation. Nanocrystals are desirable light sources for advanced display technologies. Here, the authors report on double-crowned 2D semiconductor nanoplatelets as light downconverters that offer both green and red emissions to achieve a wide color gamut.
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Pierucci D, Silly M, Tissot H, Hollander P, Sirotti F, Rochet F. Surface Photovoltage dynamics at passivated silicon surfaces: influence of substrate doping and surface termination. Faraday Discuss 2022; 236:442-460. [DOI: 10.1039/d1fd00107h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have monitored the temporal evolution of the band bending at controlled silicon surfaces after a fs laser pump excitation. Time-resolved surface photo-voltage (SPV) experiments were performed using time resolved...
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Silly MG. High resolution and time resolved photoemission spectroscopy for developing more efficient materials to reduce energy consumption and increase renewable energy production. EPJ WEB OF CONFERENCES 2022. [DOI: 10.1051/epjconf/202227301013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Due to the increase of energy consumption and the resulting ecological challenge, a collective awareness leads to the development of renewable energies and more efficient materials to increase the green energy production. Development of efficient photovoltaic materials is very closely related to their chemical and electronic properties. A better knowledge of these imbricated properties is needed, in addition to a better comprehension of their interplay with charge transport mechanisms. Exciton creation and recombination processes, charge transfer and charge collection processes take place at the surface and interface of the photoactive materials. Photoemission spectroscopy as chemical specific and surface sensitive spectroscopic technique is a method of choice on the study of physical phenomena at the origin of photoconversion efficiency. Time resolved photoemission spectroscopy has been recently renewed interest covering time scale from fs to more than seconds. It permits to probe the dynamics of relaxation of photoexcited charges and determine their lifetime. It finds application in various materials used in solar photovoltaics. In this paper, we define the physical and chemical properties determined by the combination of high resolution and time resolved photoemission spectroscopy. We show examples dealing with the development of renewable energy and energy consumption reduction in agreement with the current ecological trend for a better future.
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5
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Baby A, Marcaud G, Dappe YJ, D'Angelo M, Cantin JL, Silly M, Fratesi G. Phthalocyanine reactivity and interaction on the 6H-SiC(0001)-(3×3) surface by core-level experiments and simulations. Phys Chem Chem Phys 2022; 24:14937-14946. [DOI: 10.1039/d2cp00750a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The adsorption of phthalocyanine (H2Pc) on the 6H-SiC(0001)-(3×3) surface is investigated using X-ray photoelectron spectroscopy (XPS), near edge X-ray absorption fine structure spectroscopy (NEXAFS), and density functional theory (DFT) calculations....
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Flavell W. Spiers Memorial Lecture: Prospects for photoelectron spectroscopy. Faraday Discuss 2022; 236:9-57. [DOI: 10.1039/d2fd00071g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An overview is presented of recent advances in photoelectron spectroscopy, focussing on advances in in situ and time-resolved measurements, and in extending the sampling depth of the technique. The future...
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Pressacco F, Uhlíř V, Gatti M, Nicolaou A, Bendounan A, Arregi JA, Patel SKK, Fullerton EE, Krizmancic D, Sirotti F. Laser induced phase transition in epitaxial FeRh layers studied by pump-probe valence band photoemission. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2018; 5:034501. [PMID: 29888296 PMCID: PMC5966309 DOI: 10.1063/1.5027809] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 04/27/2018] [Indexed: 06/08/2023]
Abstract
We use time-resolved X-ray photoelectron spectroscopy to probe the electronic and magnetization dynamics in FeRh films after ultrafast laser excitations. We present experimental and theoretical results which investigate the electronic structure of FeRh during the first-order phase transition, identifying a clear signature of the magnetic phase. We find that a spin polarized feature at the Fermi edge is a fingerprint of the magnetic status of the system that is independent of the long-range ferromagnetic alignment of the magnetic domains. We use this feature to follow the phase transition induced by a laser pulse in a pump-probe experiment and find that the magnetic transition occurs in less than 50 ps and reaches its maximum in 100 ps.
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Affiliation(s)
| | | | | | - Alessandro Nicolaou
- Synchrotron SOLEIL, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Azzedine Bendounan
- Synchrotron SOLEIL, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Jon Ander Arregi
- CEITEC BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech Republic
| | - Sheena K K Patel
- Center for Memory and Recording Research, University of California, San Diego, La Jolla, California 92093-0401, USA
| | - Eric E Fullerton
- Center for Memory and Recording Research, University of California, San Diego, La Jolla, California 92093-0401, USA
| | - Damjan Krizmancic
- Instituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park S.S.14, Km 163.5, I34149 Trieste, Italy
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Peyrot D, Silly MG, Silly F. X 3 synthon geometries in two-dimensional halogen-bonded 1,3,5-tris(3,5-dibromophenyl)benzene self-assembled nanoarchitectures on Au(111)-(). Phys Chem Chem Phys 2018; 20:3918-3924. [PMID: 29318234 DOI: 10.1039/c7cp06488h] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The self-assembly of star-shaped 1,3,5-tris(3,5-dibromophenyl)benzene molecules on Au(111)-() in a vacuum is investigated using scanning tunneling microscopy and core-level spectroscopy. Scanning tunneling microscopy shows that the molecules self-assemble into a hexagonal porous halogen-bonded nanoarchitecture. This structure is stabilized by X3-A synthons composed of three type-II halogen-interactions (halogen-bonds). The molecules are oriented along the same direction in this arrangement. Domain boundaries are observed in the hcp region of the herringbone gold surface reconstruction. Molecules of the neighboring domains are rotated by 180°. The domain boundaries are stabilized by the formation of X3-B synthons composed of two type-II and one type-I halogen-interactions between molecules of the neighboring domains. Core-level spectroscopy confirms the existence of two types of halogen-interactions in the organic layer. These observations show that the gold surface reconstructions can be exploited to modify the long-range supramolecular halogen-bonded self-assemblies.
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Affiliation(s)
- David Peyrot
- TITANS, SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, F-91191 Gif sur Yvette, France.
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9
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Gallet JJ, Silly MG, Kazzi ME, Bournel F, Sirotti F, Rochet F. Chemical and kinetic insights into the Thermal Decomposition of an Oxide Layer on Si(111) from Millisecond Photoelectron Spectroscopy. Sci Rep 2017; 7:14257. [PMID: 29079787 PMCID: PMC5660199 DOI: 10.1038/s41598-017-14532-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 10/11/2017] [Indexed: 11/08/2022] Open
Abstract
Despite thermal silicon oxide desorption is a basic operation in semiconductor nanotechnology, its detailed chemical analysis has not been yet realized via time-resolved photoemission. Using an advanced acquisition system and synchrotron radiation, heating schedules with velocities as high as 100 K.s-1 were implemented and highly resolved Si 2p spectra in the tens of millisecond range were obtained. Starting from a Si(111)-7 × 7 surface oxidized in O2 at room temperature (1.4 monolayer of oxygen), changes in the Si 2p spectral shape enabled a detailed chemical analysis of the oxygen redistribution at the surface and of the nucleation, growth and reconstruction of the clean silicon areas. As desorption is an inhomogeneous surface process, the Avrami formalism was adapted to oxide desorption via an original mathematical analysis. The extracted kinetic parameters (the Avrami exponent equal to ~2, the activation energy of ~4.1 eV and a characteristic frequency) were found remarkably stable within a wide (~110 K) desorption temperature window, showing that the Avrami analysis is robust. Both the chemical and kinetic information collected from this experiment can find useful applications when desorption of the oxide layer is a fundamental step in nanofabrication processes on silicon surfaces.
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Affiliation(s)
- J-J Gallet
- Sorbonne Universités, UPMC Univ. Paris 06, and CNRS UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement (LCPMR), F-75005, Paris, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192, Gif-sur-Yvette, France
| | - M G Silly
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192, Gif-sur-Yvette, France
| | - M El Kazzi
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192, Gif-sur-Yvette, France
- Paul Scherrer Institut, 5232, Villigen-PSI, Switzerland
| | - F Bournel
- Sorbonne Universités, UPMC Univ. Paris 06, and CNRS UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement (LCPMR), F-75005, Paris, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192, Gif-sur-Yvette, France
| | - F Sirotti
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192, Gif-sur-Yvette, France
- Laboratoire de Physique de la Matière Condensée, CNRS and Ecole Polytechnique, Université Paris Saclay, F- 91128, Palaiseau, France
| | - F Rochet
- Sorbonne Universités, UPMC Univ. Paris 06, and CNRS UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement (LCPMR), F-75005, Paris, France.
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192, Gif-sur-Yvette, France.
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10
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Costantini R, Pincelli T, Cossaro A, Verdini A, Goldoni A, Cichoň S, Caputo M, Pedio M, Panaccione G, Silly M, Sirotti F, Morgante A, Dell'Angela M. Time resolved resonant photoemission study of energy level alignment at donor/acceptor interfaces. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.04.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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11
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Silly MG, Ferté T, Tordeux MA, Pierucci D, Beaulieu N, Chauvet C, Pressacco F, Sirotti F, Popescu H, Lopez-Flores V, Tortarolo M, Sacchi M, Jaouen N, Hollander P, Ricaud JP, Bergeard N, Boeglin C, Tudu B, Delaunay R, Luning J, Malinowski G, Hehn M, Baumier C, Fortuna F, Krizmancic D, Stebel L, Sergo R, Cautero G. Pump-probe experiments at the TEMPO beamline using the low-α operation mode of Synchrotron SOLEIL. JOURNAL OF SYNCHROTRON RADIATION 2017; 24:886-897. [PMID: 28664896 DOI: 10.1107/s1600577517007913] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 05/28/2017] [Indexed: 06/07/2023]
Abstract
The SOLEIL synchrotron radiation source is regularly operated in special filling modes dedicated to pump-probe experiments. Among others, the low-α mode operation is characterized by shorter pulse duration and represents the natural bridge between 50 ps synchrotron pulses and femtosecond experiments. Here, the capabilities in low-α mode of the experimental set-ups developed at the TEMPO beamline to perform pump-probe experiments with soft X-rays based on photoelectron or photon detection are presented. A 282 kHz repetition-rate femtosecond laser is synchronized with the synchrotron radiation time structure to induce fast electronic and/or magnetic excitations. Detection is performed using a two-dimensional space resolution plus time resolution detector based on microchannel plates equipped with a delay line. Results of time-resolved photoelectron spectroscopy, circular dichroism and magnetic scattering experiments are reported, and their respective advantages and limitations in the framework of high-time-resolution pump-probe experiments compared and discussed.
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Affiliation(s)
- Mathieu G Silly
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Tom Ferté
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000 Strasbourg, France
| | - Marie Agnes Tordeux
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Debora Pierucci
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Nathan Beaulieu
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Christian Chauvet
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Federico Pressacco
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Fausto Sirotti
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Horia Popescu
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Victor Lopez-Flores
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Marina Tortarolo
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Maurizio Sacchi
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Nicolas Jaouen
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Philippe Hollander
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Jean Paul Ricaud
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Nicolas Bergeard
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000 Strasbourg, France
| | - Christine Boeglin
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000 Strasbourg, France
| | - Bharati Tudu
- Sorbonne Universités, UPMC Université Paris VI, CNRS, Laboratoire de Chimie Physique - Matière et Rayonnement, Paris 75005, France
| | - Renaud Delaunay
- Sorbonne Universités, UPMC Université Paris VI, CNRS, Laboratoire de Chimie Physique - Matière et Rayonnement, Paris 75005, France
| | - Jan Luning
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin, Gif sur Yvette 91192, France
| | - Gregory Malinowski
- P2M - Institut Jean Lamour UMR7198, CNRS - Université de Lorraine, Vandoeuvre-les-Nancy 54506, France
| | - Michel Hehn
- P2M - Institut Jean Lamour UMR7198, CNRS - Université de Lorraine, Vandoeuvre-les-Nancy 54506, France
| | - Cédric Baumier
- CSNSM, Université Paris Sud and CNRS/IN2P3, Batiment 104 et 108, Orsay 91405, France
| | - Franck Fortuna
- CSNSM, Université Paris Sud and CNRS/IN2P3, Batiment 104 et 108, Orsay 91405, France
| | - Damjan Krizmancic
- Laboratorio TASC, IOM-CNR, SS 14 Km 163.5, Basovizza, I-34149 Trieste, Italy
| | - Luigi Stebel
- ELETTRA Sincrotrone Trieste SCpA, Area Science Park, Strada Statale 14 Km 163.5, I-34012 Basovizza, Italy
| | - Rudi Sergo
- ELETTRA Sincrotrone Trieste SCpA, Area Science Park, Strada Statale 14 Km 163.5, I-34012 Basovizza, Italy
| | - Giuseppe Cautero
- ELETTRA Sincrotrone Trieste SCpA, Area Science Park, Strada Statale 14 Km 163.5, I-34012 Basovizza, Italy
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Pincelli T, Grasselli F, Petrov VN, Torelli P, Rossi G. Performance of photoelectron spin polarimeters with continuous and pulsed sources: from storage rings to free electron lasers. JOURNAL OF SYNCHROTRON RADIATION 2017; 24:175-187. [PMID: 28009557 DOI: 10.1107/s1600577516017513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 11/01/2016] [Indexed: 06/06/2023]
Abstract
In this work the experimental uncertainties concerning electron spin polarization (SP) under various realistic measurement conditions are theoretically derived. The accuracy of the evaluation of the SP of the photoelectron current is analysed as a function of the detector parameters and specifications, as well as of the characteristics of the photoexcitation sources. In particular, the different behaviour of single counter or twin counter detectors when the intensity fluctuations of the source are considered have been addressed, leading to a new definition of the SP detector performance. The widely used parameter called the figure of merit is shown to be inadequate for describing the efficiency of SP polarimeters, especially when they are operated with time-structured excitation sources such as free-electron lasers. Numerical simulations have been performed and yield strong implications in the choice of the detecting instruments in spin-polarization experiments, that are constrained in a limited measurement time. Our results are therefore applied to the characteristics of a wide set of state-of-the-art spectroscopy facilities all over the world, and an efficiency diagram for SP experiments is derived. These results also define new mathematical instruments for handling the correct statistics of SP measurements in the presence of source intensity fluctuations.
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Affiliation(s)
- T Pincelli
- Dipartimento di Fisica, Università degli studi di Milano, Via Celoria 16, 20133 Milano, Italy
| | - F Grasselli
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università degli Studi di Modena e Reggio Emilia, Via Campi 213/a, Modena, Italy
| | - V N Petrov
- Saint Petersburg State Polytechnical University, Politechnicheskaya Street 29, 195251, Russian Federation
| | - P Torelli
- Laboratorio TASC, IOM-CNR, SS 14 km 163.5, Basovizza, 34149 Trieste, Italy
| | - G Rossi
- Dipartimento di Fisica, Università degli studi di Milano, Via Celoria 16, 20133 Milano, Italy
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Guan X, Becdelievre J, Meunier B, Benali A, Saint-Girons G, Bachelet R, Regreny P, Botella C, Grenet G, Blanchard NP, Jaurand X, Silly MG, Sirotti F, Chauvin N, Gendry M, Penuelas J. GaAs Core/SrTiO3 Shell Nanowires Grown by Molecular Beam Epitaxy. NANO LETTERS 2016; 16:2393-2399. [PMID: 27008537 DOI: 10.1021/acs.nanolett.5b05182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We have studied the growth of a SrTiO3 shell on self-catalyzed GaAs nanowires grown by vapor-liquid-solid assisted molecular beam epitaxy on Si(111) substrates. To control the growth of the SrTiO3 shell, the GaAs nanowires were protected using an arsenic capping/decapping procedure in order to prevent uncontrolled oxidation and/or contamination of the nanowire facets. Reflection high energy electron diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were performed to determine the structural, chemical, and morphological properties of the heterostructured nanowires. Using adapted oxide growth conditions, it is shown that most of the perovskite structure SrTiO3 shell appears to be oriented with respect to the GaAs lattice. These results are promising for achieving one-dimensional epitaxial semiconductor core/functional oxide shell nanostructures.
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Affiliation(s)
- X Guan
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, Ecole Centrale de Lyon , 36 avenue Guy de Collongue, F-69134 Ecully Cedex, France
| | - J Becdelievre
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, Ecole Centrale de Lyon , 36 avenue Guy de Collongue, F-69134 Ecully Cedex, France
| | - B Meunier
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, Ecole Centrale de Lyon , 36 avenue Guy de Collongue, F-69134 Ecully Cedex, France
| | - A Benali
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, Ecole Centrale de Lyon , 36 avenue Guy de Collongue, F-69134 Ecully Cedex, France
| | - G Saint-Girons
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, Ecole Centrale de Lyon , 36 avenue Guy de Collongue, F-69134 Ecully Cedex, France
| | - R Bachelet
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, Ecole Centrale de Lyon , 36 avenue Guy de Collongue, F-69134 Ecully Cedex, France
| | - P Regreny
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, Ecole Centrale de Lyon , 36 avenue Guy de Collongue, F-69134 Ecully Cedex, France
| | - C Botella
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, Ecole Centrale de Lyon , 36 avenue Guy de Collongue, F-69134 Ecully Cedex, France
| | - G Grenet
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, Ecole Centrale de Lyon , 36 avenue Guy de Collongue, F-69134 Ecully Cedex, France
| | - N P Blanchard
- Institut Lumière Matière (ILM), UMR5306 Université Lyon 1-CNRS Université de Lyon , 69622 Villeurbanne Cedex, France
| | - X Jaurand
- Centre Technologique des Microstructures, Université Claude Bernard Lyon 1 , 5 rue Raphael Dubois-Bâtiment Darwin B, F-69622, Villeurbanne Cedex, France
| | - M G Silly
- Synchrotron SOLEIL (TEMPO Beamline), l'Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette, France
| | - F Sirotti
- Synchrotron SOLEIL (TEMPO Beamline), l'Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette, France
| | - N Chauvin
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, INSA-Lyon , 7 avenue Jean Capelle, 69621 Villeurbanne, France
| | - M Gendry
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, Ecole Centrale de Lyon , 36 avenue Guy de Collongue, F-69134 Ecully Cedex, France
| | - J Penuelas
- Institut des Nanotechnologies de Lyon, Université de Lyon, UMR 5270-CNRS, Ecole Centrale de Lyon , 36 avenue Guy de Collongue, F-69134 Ecully Cedex, France
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14
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Pierucci D, Sediri H, Hajlaoui M, Girard JC, Brumme T, Calandra M, Velez-Fort E, Patriarche G, Silly MG, Ferro G, Soulière V, Marangolo M, Sirotti F, Mauri F, Ouerghi A. Evidence for Flat Bands near the Fermi Level in Epitaxial Rhombohedral Multilayer Graphene. ACS NANO 2015; 9:5432-9. [PMID: 25893537 DOI: 10.1021/acsnano.5b01239] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The stacking order of multilayer graphene has a profound influence on its electronic properties. In particular, it has been predicted that a rhombohedral stacking sequence displays a very flat conducting surface state: the longer the sequence, the flatter the band. In such a flat band, the role of electron-electron correlation is enhanced, possibly resulting in high Tc superconductivity, magnetic order, or charge density wave order. Here we demonstrate that rhombohedral multilayers are easily obtained by epitaxial growth on 3C-SiC(111) on a 2° off-axis 6H-SiC(0001). The resulting samples contain rhombohedral sequences of five layers on 70% of the surface. We confirm the presence of the flat band at the Fermi level by scanning tunneling spectroscopy and angle-resolved photoemission spectroscopy, in close agreement with the predictions of density functional theory calculations.
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Affiliation(s)
- Debora Pierucci
- †Laboratoire de Photonique et de Nanostructures (CNRS-LPN), Route de Nozay, 91460 Marcoussis, France
| | - Haikel Sediri
- †Laboratoire de Photonique et de Nanostructures (CNRS-LPN), Route de Nozay, 91460 Marcoussis, France
| | - Mahdi Hajlaoui
- †Laboratoire de Photonique et de Nanostructures (CNRS-LPN), Route de Nozay, 91460 Marcoussis, France
- ‡Synchrotron-SOLEIL, Saint-Aubin, BP48, F91192 Cedex Gif sur Yvette, France
| | - Jean-Christophe Girard
- †Laboratoire de Photonique et de Nanostructures (CNRS-LPN), Route de Nozay, 91460 Marcoussis, France
| | - Thomas Brumme
- §Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités, UPMC, Univ. Paris VI, MNHN, IRD, 4 place Jussieu, 75005 Paris, France
| | - Matteo Calandra
- §Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités, UPMC, Univ. Paris VI, MNHN, IRD, 4 place Jussieu, 75005 Paris, France
| | - Emilio Velez-Fort
- †Laboratoire de Photonique et de Nanostructures (CNRS-LPN), Route de Nozay, 91460 Marcoussis, France
- §Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités, UPMC, Univ. Paris VI, MNHN, IRD, 4 place Jussieu, 75005 Paris, France
| | - Gilles Patriarche
- †Laboratoire de Photonique et de Nanostructures (CNRS-LPN), Route de Nozay, 91460 Marcoussis, France
| | - Mathieu G Silly
- ‡Synchrotron-SOLEIL, Saint-Aubin, BP48, F91192 Cedex Gif sur Yvette, France
| | - Gabriel Ferro
- ∥Laboratoire des multimateriaux et Interfaces, UMR 5615, Université Claude Bernard Lyon I, 69100 Villeurbanne, France
| | - Véronique Soulière
- ∥Laboratoire des multimateriaux et Interfaces, UMR 5615, Université Claude Bernard Lyon I, 69100 Villeurbanne, France
| | - Massimiliano Marangolo
- ⊥UMR 7588, INSP, Sorbonne Universités, UPMC Univ Paris 06, 4 place Jussieu, F-75005 Paris, France
- #CNRS, UMR 7588, Institut des Nanosciences de Paris, 4 place Jussieu, F-75005 Paris, France
| | - Fausto Sirotti
- ‡Synchrotron-SOLEIL, Saint-Aubin, BP48, F91192 Cedex Gif sur Yvette, France
| | - Francesco Mauri
- §Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie, UMR CNRS 7590, Sorbonne Universités, UPMC, Univ. Paris VI, MNHN, IRD, 4 place Jussieu, 75005 Paris, France
| | - Abdelkarim Ouerghi
- †Laboratoire de Photonique et de Nanostructures (CNRS-LPN), Route de Nozay, 91460 Marcoussis, France
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15
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Toyoshima R, Kondoh H. In-situ observations of catalytic surface reactions with soft x-rays under working conditions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:083003. [PMID: 25667354 DOI: 10.1088/0953-8984/27/8/083003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Catalytic chemical reactions proceeding on solid surfaces are an important topic in fundamental science and industrial technologies such as energy conversion, pollution control and chemical synthesis. Complete understanding of the heterogeneous catalysis and improving its efficiency to an ultimate level are the eventual goals for many surface scientists. Soft x-ray is one of the prime probes to observe electronic and structural information of the target materials. Most studies in surface science using soft x-rays have been performed under ultra-high vacuum conditions due to the technical limitation, though the practical catalytic reactions proceed under ambient pressure conditions. However, recent developments of soft x-ray based techniques operating under ambient pressure conditions have opened a door to the in-situ observation of materials under realistic environments. The near-ambient-pressure x-ray photoelectron spectroscopy (NAP-XPS) using synchrotron radiation enables us to observe the chemical states of surfaces of condensed matters under the presence of gas(es) at elevated pressures, which has been hardly conducted with the conventional XPS technique. Furthermore, not only the NAP-XPS but also ambient-pressure compatible soft x-ray core-level spectroscopies, such as near-edge absorption fine structure (NEXAFS) and x-ray emission spectroscopy (XES), have been significantly contributing to the in-situ observations. In this review, first we introduce recent developments of in-situ observations using soft x-ray techniques and current status. Then we present recent new findings on catalytically active surfaces using soft x-ray techniques, particularly focusing on the NAP-XPS technique. Finally we give a perspective on the future direction of this emerging technique.
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16
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Bournel F, Gallet JJ, Köhler U, Ellakhmissi BB, Kubsky S, Carniato S, Rochet F. Propanoate grafting on (H,OH)-Si(0 0 1)-2 × 1. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:054005. [PMID: 25414150 DOI: 10.1088/0953-8984/27/5/054005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have examined the reactivity of water-covered Si(0 0 1)-2 × 1, (H,OH)-Si(0 0 1)-2 × 1, with propanoic (C2H5COOH) acid at room temperature. Using a combination of spectroscopic techniques probing the electronic structure (XPS, NEXAFS) and the vibrational spectrum (HREELS), we have proved that the acid is chemisorbed on the surface as a propanoate. Once the molecule is chemisorbed, the strong perturbation of the electronic structure of the hydroxyls, and of their vibrational spectrum, suggests that the molecule makes hydrogen bonds with the surrounding hydroxyls. As we find evidence that surface hydroxyls are involved in the adsorption reaction, we discuss how a concerted or a radical-mediated reaction (involving the surface silicon dangling bonds) could lead to water elimination and formation of the ester.
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Affiliation(s)
- Fabrice Bournel
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif sur Yvette Cedex, France. Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique, Matière et Rayonnement, 11 rue Pierre et Marie Curie, 75231 Paris Cedex, France
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17
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Silly MG, Charra F, Lux F, Lemercier G, Sirotti F. The electronic properties of mixed valence hydrated europium chloride thin film. Phys Chem Chem Phys 2015; 17:18403-12. [DOI: 10.1039/c5cp01256b] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the electronic properties of a model mixed-valence hydrated chloride europium salt by means of high resolution photoemission spectroscopy (HRPES) and resonant photoemission spectroscopy (RESPES) at the Eu 3d → 4f and 4d → 4f transitions.
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Affiliation(s)
- M. G. Silly
- TEMPO Beamline
- Synchrotron SOLEIL
- 91192 Gif-sur-Yvette Cedex
- France
| | - F. Charra
- Service de Physique de l'Etat Condensé
- CEA-CNRS UMR 3680
- Institut Rayonnement Matière de Saclay (IRAMIS)
- F-91191 Gif-sur-Yvette Cedex
- France
| | - F. Lux
- Institut Lumière Matière – UMR 5306 – Bât Jules Raulin; 22
- 69622 Villeurbanne Cedex
- France
| | - G. Lemercier
- Université Reims Champagne-Ardenne
- ICMR UMR CNRS no. 7312
- Groupe Chimie de Coordination
- 51687 Reims Cedex 2
- France
| | - F. Sirotti
- TEMPO Beamline
- Synchrotron SOLEIL
- 91192 Gif-sur-Yvette Cedex
- France
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18
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Shavorskiy A, Neppl S, Slaughter DS, Cryan JP, Siefermann KR, Weise F, Lin MF, Bacellar C, Ziemkiewicz MP, Zegkinoglou I, Fraund MW, Khurmi C, Hertlein MP, Wright TW, Huse N, Schoenlein RW, Tyliszczak T, Coslovich G, Robinson J, Kaindl RA, Rude BS, Ölsner A, Mähl S, Bluhm H, Gessner O. Sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy setup for pulsed and constant wave X-ray light sources. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:093102. [PMID: 25273702 DOI: 10.1063/1.4894208] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
An apparatus for sub-nanosecond time-resolved ambient-pressure X-ray photoelectron spectroscopy studies with pulsed and constant wave X-ray light sources is presented. A differentially pumped hemispherical electron analyzer is equipped with a delay-line detector that simultaneously records the position and arrival time of every single electron at the exit aperture of the hemisphere with ~0.1 mm spatial resolution and ~150 ps temporal accuracy. The kinetic energies of the photoelectrons are encoded in the hit positions along the dispersive axis of the two-dimensional detector. Pump-probe time-delays are provided by the electron arrival times relative to the pump pulse timing. An average time-resolution of (780 ± 20) ps (FWHM) is demonstrated for a hemisphere pass energy E(p) = 150 eV and an electron kinetic energy range KE = 503-508 eV. The time-resolution of the setup is limited by the electron time-of-flight (TOF) spread related to the electron trajectory distribution within the analyzer hemisphere and within the electrostatic lens system that images the interaction volume onto the hemisphere entrance slit. The TOF spread for electrons with KE = 430 eV varies between ~9 ns at a pass energy of 50 eV and ~1 ns at pass energies between 200 eV and 400 eV. The correlation between the retarding ratio and the TOF spread is evaluated by means of both analytical descriptions of the electron trajectories within the analyzer hemisphere and computer simulations of the entire trajectories including the electrostatic lens system. In agreement with previous studies, we find that the by far dominant contribution to the TOF spread is acquired within the hemisphere. However, both experiment and computer simulations show that the lens system indirectly affects the time resolution of the setup to a significant extent by inducing a strong dependence of the angular spread of electron trajectories entering the hemisphere on the retarding ratio. The scaling of the angular spread with the retarding ratio can be well approximated by applying Liouville's theorem of constant emittance to the electron trajectories inside the lens system. The performance of the setup is demonstrated by characterizing the laser fluence-dependent transient surface photovoltage response of a laser-excited Si(100) sample.
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Affiliation(s)
- Andrey Shavorskiy
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Stefan Neppl
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Daniel S Slaughter
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - James P Cryan
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Katrin R Siefermann
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Fabian Weise
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Ming-Fu Lin
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Camila Bacellar
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Michael P Ziemkiewicz
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Ioannis Zegkinoglou
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Matthew W Fraund
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Champak Khurmi
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Marcus P Hertlein
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Travis W Wright
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Nils Huse
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Robert W Schoenlein
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Tolek Tyliszczak
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Giacomo Coslovich
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Joseph Robinson
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Robert A Kaindl
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Bruce S Rude
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | | | - Sven Mähl
- SPECS Surface Nano Analysis GmbH, 13355 Berlin, Germany
| | - Hendrik Bluhm
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Oliver Gessner
- Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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19
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Spencer BF, Cliffe MJ, Graham DM, Hardman SJO, Seddon EA, Syres KL, Thomas AG, Sirotti F, Silly MG, Akhtar J, O'Brien P, Fairclough SM, Smith JM, Chattopadhyay S, Flavell WR. Dynamics in next-generation solar cells: time-resolved surface photovoltage measurements of quantum dots chemically linked to ZnO (101̄0). Faraday Discuss 2014; 171:275-98. [DOI: 10.1039/c4fd00019f] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The charge dynamics at the surface of the transparent conducting oxide and photoanode material ZnO are investigated in the presence and absence of light-harvesting colloidal quantum dots (QDs). The time-resolved change in surface potential upon photoexcitation has been measured in the m-plane ZnO (101̄0) using a laser pump-synchrotron X-ray probe methodology. By varying the oxygen annealing conditions, and hence the oxygen vacancy concentration of the sample, we find that dark carrier lifetimes at the ZnO surface vary from hundreds of μs to ms timescales, i.e. a persistent photoconductivity (PPC) is observed. The highly-controlled nature of our experiments under ultra-high vacuum (UHV), and the use of band-gap and sub-band-gap photoexcitation, allow us to demonstrate that defect states ca. 340 meV above the valence band edge are directly associated with the PPC, and that the PPC mediated by these defects dominates over the oxygen photodesorption mechanism. These observations are consistent with the hypothesis that ionized oxygen vacancy states are responsible for the PPC in ZnO. The effect of chemically linking two colloidal QD systems (type I PbS and type II CdS–ZnSe) to the surface has also been investigated. Upon deposition of the QDs onto the surface, the dark carrier lifetime and the surface photovoltage are reduced, suggesting a direct injection of charge carriers into the ZnO conduction band. The results are discussed in the context of the development of next-generation solar cells.
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Affiliation(s)
- Ben F. Spencer
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
- The Cockcroft Institute
- Sci-Tech Daresbury, Keckwick Lane, Daresbury
| | - Matthew J. Cliffe
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
- The Cockcroft Institute
- Sci-Tech Daresbury, Keckwick Lane, Daresbury
| | - Darren M. Graham
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
| | - Samantha J. O. Hardman
- Manchester Institute of Biotechnology
- Faculty of Life Sciences
- University of Manchester
- Manchester M1 7DN, United Kingdom
| | - Elaine A. Seddon
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
- The Cockcroft Institute
- Sci-Tech Daresbury, Keckwick Lane, Daresbury
| | - Karen L. Syres
- School of Chemistry
- The University of Nottingham
- Nottingham NG7 2RD, United Kingdom
| | - Andrew G. Thomas
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
| | | | | | - Javeed Akhtar
- Department of Chemistry
- University of Manchester
- Manchester M13 9PL, United Kingdom
- Department of Physics
- Nano-Science & Materials Synthesis Laboratory
| | - Paul O'Brien
- Department of Chemistry
- University of Manchester
- Manchester M13 9PL, United Kingdom
| | | | - Jason M. Smith
- Department of Materials
- University of Oxford
- Oxford OX1 3PH, United Kingdom
| | - Swapan Chattopadhyay
- The Cockcroft Institute
- Sci-Tech Daresbury, Keckwick Lane, Daresbury
- Warrington WA4 4AD, United Kingdom
| | - Wendy R. Flavell
- School of Physics and Astronomy and the Photon Science Institute
- The University of Manchester
- , United Kingdom
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20
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Neppl S, Shavorskiy A, Zegkinoglou I, Fraund M, Slaughter DS, Troy T, Ziemkiewicz MP, Ahmed M, Gul S, Rude B, Zhang JZ, Tremsin AS, Glans PA, Liu YS, Wu CH, Guo J, Salmeron M, Bluhm H, Gessner O. Capturing interfacial photoelectrochemical dynamics with picosecond time-resolved X-ray photoelectron spectroscopy. Faraday Discuss 2014; 171:219-41. [DOI: 10.1039/c4fd00036f] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Time-resolved core-level spectroscopy using laser pulses to initiate and short X-ray pulses to trace photoinduced processes has the unique potential to provide electronic state- and atomic site-specific insight into fundamental electron dynamics in complex systems. Time-domain studies using transient X-ray absorption and emission techniques have proven extremely valuable to investigate electronic and structural dynamics in isolated and solvated molecules. Here, we describe the implementation of a picosecond time-resolved X-ray photoelectron spectroscopy (TRXPS) technique at the Advanced Light Source (ALS) and its application to monitor photoinduced electron dynamics at the technologically pertinent interface formed by N3 dye molecules anchored to nanoporous ZnO. Indications for a dynamical chemical shift of the Ru3d photoemission line originating from the N3 metal centre are observed ∼30 ps after resonant HOMO–LUMO excitation with a visible laser pump pulse. The transient changes in the TRXPS spectra are accompanied by a characteristic surface photovoltage (SPV) response of the ZnO substrate on a pico- to nanosecond time scale. The interplay between the two phenomena is discussed in the context of possible electronic relaxation and recombination pathways that lead to the neutralisation of the transiently oxidised dye after ultrafast electron injection. A detailed account of the experimental technique is given including an analysis of the chemical modification of the nano-structured ZnO substrate during extended periods of solution-based dye sensitisation and its relevance for studies using surface-sensitive spectroscopy techniques.
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Affiliation(s)
- Stefan Neppl
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Andrey Shavorskiy
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Ioannis Zegkinoglou
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Matthew Fraund
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Daniel S. Slaughter
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Tyler Troy
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | | | - Musahid Ahmed
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Sheraz Gul
- Advanced Light Source
- Lawrence Berkeley National Laboratory
- Berkeley, USA
- Department of Chemistry and Biochemistry
- University of California Santa Cruz
| | - Bruce Rude
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Jin Z. Zhang
- Department of Chemistry and Biochemistry
- University of California Santa Cruz
- Santa Cruz, USA
| | - Anton S. Tremsin
- Space Sciences Laboratory
- University of California Berkeley
- Berkeley, USA
| | - Per-Anders Glans
- Advanced Light Source
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Yi-Sheng Liu
- Advanced Light Source
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Cheng Hao Wu
- Materials Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
- Department of Chemistry
- University of California Berkeley
| | - Jinghua Guo
- Advanced Light Source
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Miquel Salmeron
- Materials Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Hendrik Bluhm
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
| | - Oliver Gessner
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley, USA
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21
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Cuif JP, Bendounan A, Dauphin Y, Nouet J, Sirotti F. Synchrotron-based photoelectron spectroscopy provides evidence for a molecular bond between calcium and mineralizing organic phases in invertebrate calcareous skeletons. Anal Bioanal Chem 2013; 405:8739-48. [DOI: 10.1007/s00216-013-7312-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 08/15/2013] [Indexed: 11/29/2022]
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22
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Risterucci P, Held G, Bendounan A, Silly MG, Chauvet C, Pierucci D, Beaulieu N, Sirotti F. Preventing carbon contamination of optical devices for X-rays: the effect of oxygen on photon-induced dissociation of CO on platinum. JOURNAL OF SYNCHROTRON RADIATION 2012; 19:570-573. [PMID: 22713891 DOI: 10.1107/s090904951202050x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 05/07/2012] [Indexed: 06/01/2023]
Abstract
Platinum is one of the most common coatings used to optimize mirror reflectivity in soft X-ray beamlines. Normal operation results in optics contamination by carbon-based molecules present in the residual vacuum of the beamlines. The reflectivity reduction induced by a carbon layer at the mirror surface is a major problem in synchrotron radiation sources. A time-dependent photoelectron spectroscopy study of the chemical reactions which take place at the Pt(111) surface under operating conditions is presented. It is shown that the carbon contamination layer growth can be stopped and reversed by low partial pressures of oxygen for optics operated in intense photon beams at liquid-nitrogen temperature. For mirrors operated at room temperature the carbon contamination observed for equivalent partial pressures of CO is reduced and the effects of oxygen are observed on a long time scale.
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Affiliation(s)
- Paul Risterucci
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
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23
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Stebel L, Malvestuto M, Capogrosso V, Sigalotti P, Ressel B, Bondino F, Magnano E, Cautero G, Parmigiani F. Time-resolved soft x-ray absorption setup using multi-bunch operation modes at synchrotrons. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2011; 82:123109. [PMID: 22225201 DOI: 10.1063/1.3669787] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Here, we report on a novel experimental apparatus for performing time-resolved soft x-ray absorption spectroscopy in the sub-ns time scale using non-hybrid multi-bunch mode synchrotron radiation. The present setup is based on a variable repetition rate Ti:sapphire laser (pump pulse) synchronized with the ~500 MHz x-ray synchrotron radiation bunches and on a detection system that discriminates and singles out the significant x-ray photon pulses by means of a custom made photon counting unit. The whole setup has been validated by measuring the time evolution of the L(3) absorption edge during the melting and the solidification of a Ge single crystal irradiated by an intense ultrafast laser pulse. These results pave the way for performing synchrotron time-resolved experiments in the sub-ns time domain with variable repetition rate exploiting the full flux of the synchrotron radiation.
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Affiliation(s)
- L Stebel
- Sincrotrone Trieste, S.S. 14 km 163.5, Area Science Park, 34149 Basovizza (Ts), Italy
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Guzzo M, Lani G, Sottile F, Romaniello P, Gatti M, Kas JJ, Rehr JJ, Silly MG, Sirotti F, Reining L. Valence electron photoemission spectrum of semiconductors: ab initio description of multiple satellites. PHYSICAL REVIEW LETTERS 2011; 107:166401. [PMID: 22107408 DOI: 10.1103/physrevlett.107.166401] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Indexed: 05/31/2023]
Abstract
The experimental valence band photoemission spectrum of semiconductors exhibits multiple satellites that cannot be described by the GW approximation for the self-energy in the framework of many-body perturbation theory. Taking silicon as a prototypical example, we compare experimental high energy photoemission spectra with GW calculations and analyze the origin of the GW failure. We then propose an approximation to the functional differential equation that determines the exact one-body Green's function, whose solution has an exponential form. This yields a calculated spectrum, including cross sections, secondary electrons, and an estimate for extrinsic and interference effects, in excellent agreement with experiment. Our result can be recast as a dynamical vertex correction beyond GW, giving hints for further developments.
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Affiliation(s)
- Matteo Guzzo
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA-DSM, F-91128 Palaiseau, France.
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