1
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Liebetrau M, Dorenkamp Y, Bünermann O, Behler J. Hydrogen atom scattering at the Al 2O 3(0001) surface: a combined experimental and theoretical study. Phys Chem Chem Phys 2024; 26:1696-1708. [PMID: 38126723 DOI: 10.1039/d3cp04729f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Investigating atom-surface interactions is the key to an in-depth understanding of chemical processes at interfaces, which are of central importance in many fields - from heterogeneous catalysis to corrosion. In this work, we present a joint experimental and theoretical effort to gain insights into the atomistic details of hydrogen atom scattering at the α-Al2O3(0001) surface. Surprisingly, this system has been hardly studied to date, although hydrogen atoms as well as α-Al2O3 are omnipresent in catalysis as reactive species and support oxide, respectively. We address this system by performing hydrogen atom beam scattering experiments and molecular dynamics (MD) simulations based on a high-dimensional machine learning potential trained to density functional theory data. Using this combination of methods we are able to probe the properties of the multidimensional potential energy surface governing the scattering process. Specifically, we compare the angular distribution and the kinetic energy loss of the scattered atoms obtained in experiment with a large number of MD trajectories, which, moreover, allow to identify the underlying impact sites at the surface.
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Affiliation(s)
- Martin Liebetrau
- Lehrstuhl für Theoretische Chemie II, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
- Research Center Chemical Sciences and Sustainability, Research Alliance Ruhr, D-44780 Bochum, Germany
| | - Yvonne Dorenkamp
- Georg-August-Universität Göttingen, Institut für Physikalische Chemie, Tammannstraße 6, D-37077 Göttingen, Germany.
| | - Oliver Bünermann
- Georg-August-Universität Göttingen, Institut für Physikalische Chemie, Tammannstraße 6, D-37077 Göttingen, Germany.
- Department of Dynamics at Surfaces, Max-Planck-Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37007 Göttingen, Germany
- International Center of Advanced Studies of Energy Conversion, Georg-August-Universität Göttingen, Tammannstraße 6, D-37077 Göttingen, Germany
| | - Jörg Behler
- Lehrstuhl für Theoretische Chemie II, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
- Research Center Chemical Sciences and Sustainability, Research Alliance Ruhr, D-44780 Bochum, Germany
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2
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Sassi M, Rosso KM. First principles simulations of MgO(100) surface hydration at ambient conditions. Phys Chem Chem Phys 2024; 26:2269-2276. [PMID: 38165646 DOI: 10.1039/d3cp04848a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Developing a better understanding of water ordering and hydroxylation at oxide mineral surfaces is important across a breath of application spaces. Recent vibrational sum frequency generation (vSFG) measurements on MgO(100) surfaces at ambient conditions showed that water dissociates and hydroxylates the surface yielding a non-hydrogen bonded hydroxyl species. Starting from previously determined water hydroxylation patterns on MgO(100), we performed ab initio thermodynamic calculations and vibrational analysis to compare with the vSFG observations. At ambient conditions (i.e., T = 298.15 K and pH2O = 32 mbar), the most thermodynamically favorable surface hydroxylation is found to be p(3 × 2) - 8H2O, involving a dissociation of 25% of the adsorbed water. Analysis of the vibrational density of states for this hydroxylation configuration yielded three different hydrogen bonding environments with the frequency of the peaks in very good agreement with the vSFG measurements. However, the non-H-bonded spectral feature on this surface is predicted to be similar to that expected for Mg(OH)2, a thermodynamically downhill alteration of the surface that must be independently ruled out before one can be fully confident in the apparent theory/vSFG agreement. Our study provides more insights into the ordering and structure of water monolayer at MgO(100) surface at ambient conditions and completes previous theoretical and experimental analysis performed at low temperature and ultra-high vacuum conditions.
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Affiliation(s)
- Michel Sassi
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
| | - Kevin M Rosso
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
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3
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Lazzari R, Goniakowski J, Cabailh G, Cavallotti R, Jupille J, Trcera N, Lagarde P. Transition from monolayer-thick 2D to 3D nano-clusters on α-Al 2O 3(0001). NANOSCALE 2023; 15:15608-15618. [PMID: 37706502 DOI: 10.1039/d3nr03521b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
This paper reports on the long-standing puzzle of the atomic structure of the Ag/α-Al2O3(0001) interface by combining X-ray absorption spectroscopy, to determine Ag local environment [i.e. average Ag-Ag (dAg-Ag) and Ag-O (dAg-O) interatomic distances and Ag coordination numbers (CN)], and numerical simulations on nanometric-sized particles. The experimental key was the capability of a structural study of clusters involving only a few atoms. The concomitant decrease of dAg-Ag and CN with decreasing cluster size provides unambiguous fingerprints for the dimensionality of the Ag clusters in the subnanometric regime leading to a series of unexpected results regarding the size-dependent interface structures. At low coverage, Ag atoms sit on surface Al sites to form buckled monolayer-thick islands associated with a Ag-Ag distance (2.75 Å) which fits the alumina lattice. Upon increasing Ag coverage, as 3D clusters appear, the Ag interface atoms tend to leave Al sites to sit atop O atoms as dAg-Ag increases. The then highlighted size-dependent evolution, is built on structural models which seemed so far contradictory in a static vision of the interface. Theory generalizes the case as it predicts the existence of alumina-supported 2D clusters of Pd and Pt at small coverage and a similar 2D-3D transition upon increasing the size. The structural transformation from 2D Ag clusters to macroscopic 3D islands is accompanied by a noticeable reduction of adhesion energy at the Ag/α-Al2O3(0001) interface.
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Affiliation(s)
- Rémi Lazzari
- CNRS, Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
| | - Jacek Goniakowski
- CNRS, Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
| | - Gregory Cabailh
- CNRS, Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
| | - Rémi Cavallotti
- CNRS, Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
| | - Jacques Jupille
- CNRS, Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
| | - Nicolas Trcera
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, 91190 Saint Aubin, France
| | - Pierre Lagarde
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, 91190 Saint Aubin, France
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4
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Tavani F, Busato M, Braglia L, Mauri S, Torelli P, D’Angelo P. Caught while Dissolving: Revealing the Interfacial Solvation of the Mg 2+ Ions on the MgO Surface. ACS APPLIED MATERIALS & INTERFACES 2022; 14:38370-38378. [PMID: 35968677 PMCID: PMC9412945 DOI: 10.1021/acsami.2c10005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
Interfaces between water and materials are ubiquitous and are crucial in materials sciences and in biology, where investigating the interaction of water with the surface under ambient conditions is key to shedding light on the main processes occurring at the interface. Magnesium oxide is a popular model system to study the metal oxide-water interface, where, for sufficient water loadings, theoretical models have suggested that reconstructed surfaces involving hydrated Mg2+ metal ions may be energetically favored. In this work, by combining experimental and theoretical surface-selective ambient pressure X-ray absorption spectroscopy with multivariate curve resolution and molecular dynamics, we evidence in real time the occurrence of Mg2+ solvation at the interphase between MgO and solvating media such as water and methanol (MeOH). Further, we show that the Mg2+ surface ions undergo a reversible solvation process, we prove the dissolution/redeposition of the Mg2+ ions belonging to the MgO surface, and we demonstrate the formation of octahedral [Mg(H2O)6]2+ and [Mg(MeOH)6]2+ intermediate solvated species. The unique surface, electronic, and structural sensitivity of the developed technique may be beneficial to access often elusive properties of low-Z metal ion intermediates involved in interfacial processes of chemical and biological interest.
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Affiliation(s)
- Francesco Tavani
- Dipartimento
di Chimica, Università di Roma “La
Sapienza”, P.le A. Moro 5, 00185 Roma, Italy
| | - Matteo Busato
- Dipartimento
di Chimica, Università di Roma “La
Sapienza”, P.le A. Moro 5, 00185 Roma, Italy
| | - Luca Braglia
- CNR
- Istituto Officina dei Materiali, TASC, I-34149 Trieste, Italy
| | - Silvia Mauri
- CNR
- Istituto Officina dei Materiali, TASC, I-34149 Trieste, Italy
- Dipartimento
di Fisica, Università di Trieste, Via A. Valerio 2, 34127 Trieste, Italy
| | - Piero Torelli
- CNR
- Istituto Officina dei Materiali, TASC, I-34149 Trieste, Italy
| | - Paola D’Angelo
- Dipartimento
di Chimica, Università di Roma “La
Sapienza”, P.le A. Moro 5, 00185 Roma, Italy
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5
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Messaykeh M, Chenot S, David P, Cabailh G, Jupille J, Koltsov A, Lagarde P, Trcera N, Goniakowski J, Lazzari R. Core level shifts as indicators of Cr chemistry on hydroxylated α-Al 2O 3(0001): a combined photoemission and first-principles study. Phys Chem Chem Phys 2021; 23:21852-21862. [PMID: 34554163 DOI: 10.1039/d1cp03224k] [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 Cr/α-Al2O3(0001) interface has been explored by X-ray photoemission spectroscopy, X-ray absorption spectroscopy (XAS) and ab initio first-principles calculations of core level shifts including final state effects. After an initial oxidation via a reaction with residual surface OH but no reduction of the alumina substrate, Cr grows in a metallic form without any chemical effect on the initially oxidized Cr. However, Cr metal lacks crystallinity. Long-range (reflection high energy electron diffraction) and short-range (XAS) order are hardly observed. Thus photoemission combined with atomistic simulations becomes a unique tool to explore the chemistry and environment at the Cr/alumina interface. Cr 2p, O 1s and Al 2s shifted components are all explained by the formation of moieties involving Cr3+ and/or Cr4+ and of metallic Cr0, which supports the previously found Cr buffer mechanism for poorly adhesive metals. Beyond the situation under study, the present data demonstrate the ability of a combined experimental and theoretical approach of core-level shifts to exhaustively describe the general case of disordered metal/oxide interfaces.
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Affiliation(s)
- Maya Messaykeh
- CNRS/Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
| | - Stéphane Chenot
- CNRS/Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
| | - Pascal David
- CNRS/Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
| | - Gregory Cabailh
- CNRS/Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
| | - Jacques Jupille
- CNRS/Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
| | - Alexey Koltsov
- ArcelorMittal Maizières Research, Voie Romaine, F-57280 Maizières-lès-Metz, France
| | - Pierre Lagarde
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette, France
| | - Nicolas Trcera
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette, France
| | - Jacek Goniakowski
- CNRS/Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
| | - Rémi Lazzari
- CNRS/Sorbonne Université, Institut des NanoSciences de Paris, UMR 7588, 4 Place Jussieu, F-75005 Paris, France.
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6
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Chiral high-harmonic generation and spectroscopy on solid surfaces using polarization-tailored strong fields. Nat Commun 2021; 12:3723. [PMID: 34140484 PMCID: PMC8211651 DOI: 10.1038/s41467-021-23999-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 05/24/2021] [Indexed: 11/09/2022] Open
Abstract
Strong-field methods in solids enable new strategies for ultrafast nonlinear spectroscopy and provide all-optical insights into the electronic properties of condensed matter in reciprocal and real space. Additionally, solid-state media offers unprecedented possibilities to control high-harmonic generation using modified targets or tailored excitation fields. Here we merge these important points and demonstrate circularly-polarized high-harmonic generation with polarization-matched excitation fields for spectroscopy of chiral electronic properties at surfaces. The sensitivity of our approach is demonstrated for structural helicity and termination-mediated ferromagnetic order at the surface of silicon-dioxide and magnesium oxide, respectively. Circularly polarized radiation emanating from a solid sample now allows to add basic symmetry properties as chirality to the arsenal of strong-field spectroscopy in solids. Together with its inherent temporal (femtosecond) resolution and non-resonant broadband spectrum, the polarization control of high harmonics from condensed matter can illuminate ultrafast and strong field dynamics of surfaces, buried layers or thin films. Strong nonlinearities in solid state materials can lead to interesting applications in photonics. Here the authors study chiral high-harmonic generation at SiO2 and MgO surfaces using bi-circular two-color driving fields and extract information on crystal properties.
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7
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Schwab T, Aicher K, Razouq H, Zickler GA, Diwald O. Segregation Engineering in MgO Nanoparticle-Derived Ceramics: The Impact of Calcium and Barium Admixtures on the Microstructure and Light Emission Properties. ACS APPLIED MATERIALS & INTERFACES 2021; 13:25493-25502. [PMID: 34009927 PMCID: PMC8176451 DOI: 10.1021/acsami.1c02931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 05/06/2021] [Indexed: 06/12/2023]
Abstract
Nanostructured segregates of alkaline earth oxides exhibit bright photoluminescence emission and great potential as components of earth-abundant inorganic phosphors. We evaluated segregation engineering of Ca2+- and Ba2+-admixtures in sintered MgO nanocube-derived compacts. Compaction and sintering transform the nanoparticle agglomerates into ceramics with residual porosities of Φ = 24-28%. Size mismatch drives admixture segregation into the intergranular region, where they form thin metal oxide films and inclusions decorating grain boundaries and pores. An important trend in the median grain size evolution of the sintered bodies with dCa(10 at. %) = 90 nm < dBa(1 at. %) = 160 nm < dMgO = 250 nm ∼ dCa(1 at. %) = 280 nm < dBa(10 at. %) = 870 nm is rationalized by segregation and interface energies, barriers for ion diffusion, admixture concentration, and the increasing surface basicity of the grains during processing. We outline the potential of admixtures on interface engineering in MgO nanocrystal-derived ceramics and demonstrate that in the sintered compacts, the photoluminescence emission originating from the grain surfaces is retained. Interior parts of the ceramic, which are accessible to molecules from the gas phase, contribute with oxygen partial pressure-dependent intensities to light emission.
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8
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Si Y, Li M, Zhou Z, Liu M, Prezhdo O. Improved description of hematite surfaces by the SCAN functional. J Chem Phys 2020; 152:024706. [PMID: 31941307 DOI: 10.1063/1.5134951] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Controversies on the surface termination of α-Fe2O3 (0001) focus on its surface stoichiometry dependence on the oxygen chemical potential. Density functional theory (DFT) calculations applying the commonly accepted Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional to a strongly correlated system predict the best matching surface termination, but would produce a delocalization error, resulting in an inappropriate bandgap, and thus are not applicable for comprehensive hematite system studies. Besides, the widely applied PBE+U scheme cannot provide evidence for existence of some of the successfully synthesized stoichiometric α-Fe2O3 (0001) surfaces. Hence, a better scheme is needed for hematite DFT studies. This work investigates whether the strongly constrained and appropriately normed (SCAN) approximation reported by Perdew et al. could provide an improved result for the as-mentioned problem, and whether SCAN can be applied to hematite systems. By comparing the results calculated with the PBE, SCAN, PBE+U, and SCAN+U schemes, we find that SCAN and SCAN+U improves the description of the electronic structure of different stoichiometric α-Fe2O3 (0001) surfaces with respect to the PBE results, and that they give a consistent prediction of the surface terminations. Besides, the bulk lattice constants and the bulk density of states are also improved with the SCAN functional. This study provides a general characterization of the α-Fe2O3 (0001) surfaces and rationalizes how the SCAN approximation improves the results of hematite surface calculations.
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Affiliation(s)
- Yitao Si
- International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, People's Republic of China
| | - Mingtao Li
- International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, People's Republic of China
| | - Zhaohui Zhou
- Chemical Engineering and Technology, School of Environmental Science and Engineering, Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Ministry of Education, Chang'an University, Xi'an 710064, China
| | - Maochang Liu
- International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, People's Republic of China
| | - Oleg Prezhdo
- Deparment of Chemistry, University of Southern California, Los Angeles, California 90089, USA
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9
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Niedermaier M, Taniteerawong C, Schwab T, Zickler G, Bernardi J, Diwald O. Impurity Segregation and Nanoparticle Reorganization of Indium Doped MgO Cubes. CHEMNANOMAT : CHEMISTRY OF NANOMATERIALS FOR ENERGY, BIOLOGY AND MORE 2019; 5:634-641. [PMID: 31231606 PMCID: PMC6563704 DOI: 10.1002/cnma.201900077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 02/26/2019] [Indexed: 06/09/2023]
Abstract
Metal oxide nanocomposites are non-equilibrium solids and promising precursors for functional materials. Annealing of such materials can provide control over impurity segregation and, depending on the level of consolidation, represents a versatile approach to engineer free surfaces, particle-particle interfaces and grain boundaries. Starting with indium-magnesium-oxide nanoparticle powders obtained via injection of an indium organic precursor into the magnesium combustion flame and subsequent particle quenching in argon, we investigated the stability of the trivalent In3+ ions in the host lattice of MgO nanoparticles by determining grain growth, morphology evolution and impurity segregation. The latter process is initiated by vacuum annealing at 873 K and can be tracked at 1173 K on a time scale of minutes. In the first instance the surface segregated indium wets the nanoparticle interfaces. After prolonged annealing indium evaporates and leaves the powder via the gas phase. Resulting MgO nanocubes are devoid of residual indium, regain their high morphological definition and show spectroscopic fingerprints (UV Diffuse Reflectance and Photoluminescence emission) that are characteristic of electronically unperturbed MgO cube corner and edge features. The results of this combined XRD, TEM, and spectroscopy study reveal the parameter window within which control over indium segregation is used to introduce a semiconducting metal oxide component into the intergranular region between insulating MgO nanograins.
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Affiliation(s)
- Matthias Niedermaier
- Department of Chemistry and Physics of MaterialsUniversity of SalzburgJakob-Haringer-Strasse 2a5020SalzburgAustria
| | - Chatpawee Taniteerawong
- Department of Chemistry and Physics of MaterialsUniversity of SalzburgJakob-Haringer-Strasse 2a5020SalzburgAustria
| | - Thomas Schwab
- Department of Chemistry and Physics of MaterialsUniversity of SalzburgJakob-Haringer-Strasse 2a5020SalzburgAustria
| | - Gregor Zickler
- Department of Chemistry and Physics of MaterialsUniversity of SalzburgJakob-Haringer-Strasse 2a5020SalzburgAustria
| | - Johannes Bernardi
- University Service Centre for Transmission Electron MicroscopyTechnische Universität Wien1040ViennaAustria
| | - Oliver Diwald
- Department of Chemistry and Physics of MaterialsUniversity of SalzburgJakob-Haringer-Strasse 2a5020SalzburgAustria
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10
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Kraushofer F, Jakub Z, Bichler M, Hulva J, Drmota P, Weinold M, Schmid M, Setvin M, Diebold U, Blaha P, Parkinson GS. Atomic-Scale Structure of the Hematite α-Fe 2O 3(11̅02) "R-Cut" Surface. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2018; 122:1657-1669. [PMID: 29492182 PMCID: PMC5823487 DOI: 10.1021/acs.jpcc.7b10515] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/08/2017] [Indexed: 05/26/2023]
Abstract
The α-Fe2O3(11̅02) surface (also known as the hematite r-cut or (012) surface) was studied using low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), scanning tunneling microscopy (STM), noncontact atomic force microscopy (nc-AFM), and ab initio density functional theory (DFT)+U calculations. Two surface structures are stable under ultrahigh vacuum (UHV) conditions; a stoichiometric (1 × 1) surface can be prepared by annealing at 450 °C in ≈10-6 mbar O2, and a reduced (2 × 1) reconstruction is formed by UHV annealing at 540 °C. The (1 × 1) surface is close to an ideal bulk termination, and the undercoordinated surface Fe atoms reduce the surface bandgap by ≈0.2 eV with respect to the bulk. The work function is measured to be 5.7 ± 0.2 eV, and the VBM is located 1.5 ± 0.1 eV below EF. The images obtained from the (2 × 1) reconstruction cannot be reconciled with previously proposed models, and a new "alternating trench" structure is proposed based on an ordered removal of lattice oxygen atoms. DFT+U calculations show that this surface is favored in reducing conditions and that 4-fold-coordinated Fe2+ cations at the surface introduce gap states approximately 1 eV below EF. The work function on the (2 × 1) termination is 5.4 ± 0.2 eV.
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Affiliation(s)
- Florian Kraushofer
- Institute
of Applied Physics, Vienna University of
Technology, Vienna, Austria
| | - Zdenek Jakub
- Institute
of Applied Physics, Vienna University of
Technology, Vienna, Austria
| | - Magdalena Bichler
- Institute
of Materials Chemistry, Vienna University
of Technology, Vienna, Austria
| | - Jan Hulva
- Institute
of Applied Physics, Vienna University of
Technology, Vienna, Austria
| | - Peter Drmota
- Institute
of Applied Physics, Vienna University of
Technology, Vienna, Austria
| | - Michael Weinold
- Institute
of Applied Physics, Vienna University of
Technology, Vienna, Austria
| | - Michael Schmid
- Institute
of Applied Physics, Vienna University of
Technology, Vienna, Austria
| | - Martin Setvin
- Institute
of Applied Physics, Vienna University of
Technology, Vienna, Austria
| | - Ulrike Diebold
- Institute
of Applied Physics, Vienna University of
Technology, Vienna, Austria
| | - Peter Blaha
- Institute
of Materials Chemistry, Vienna University
of Technology, Vienna, Austria
| | - Gareth S. Parkinson
- Institute
of Applied Physics, Vienna University of
Technology, Vienna, Austria
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11
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Influence of nickel(II) oxide surface magnetism on molecule adsorption: A first-principles study. CHINESE JOURNAL OF CATALYSIS 2017. [DOI: 10.1016/s1872-2067(17)62883-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Zhou Y, Li Y, Shen W. Shape Engineering of Oxide Nanoparticles for Heterogeneous Catalysis. Chem Asian J 2016; 11:1470-88. [DOI: 10.1002/asia.201600115] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Yan Zhou
- State Key Laboratory of Catalysis; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian 116023 China
| | - Yong Li
- State Key Laboratory of Catalysis; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian 116023 China
| | - Wenjie Shen
- State Key Laboratory of Catalysis; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian 116023 China
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13
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Ovcharenko R, Voloshina E, Sauer J. Water adsorption and O-defect formation on Fe2O3(0001) surfaces. Phys Chem Chem Phys 2016; 18:25560-25568. [DOI: 10.1039/c6cp05313k] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Detailed theoretical understanding of the interaction between pristine and defective α-Fe2O3(0001) surfaces and an isolated water molecule.
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Affiliation(s)
- Roman Ovcharenko
- Humboldt-Universität zu Berlin
- Institut für Chemie
- 10099 Berlin
- Germany
| | - Elena Voloshina
- Humboldt-Universität zu Berlin
- Institut für Chemie
- 10099 Berlin
- Germany
| | - Joachim Sauer
- Humboldt-Universität zu Berlin
- Institut für Chemie
- 10099 Berlin
- Germany
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14
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Battiato S, Giangregorio MM, Catalano MR, Lo Nigro R, Losurdo M, Malandrino G. Morphology-controlled synthesis of NiO films: the role of the precursor and the effect of the substrate nature on the films' structural/optical properties. RSC Adv 2016. [DOI: 10.1039/c6ra05510a] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
NiO thin films were grown through MOCVD on quartz and LaAlO3 (001) single crystal substrates. The relationship between the precursor/substrate nature and film properties allowed to define the best conditions to grow good quality NiO films.
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Affiliation(s)
- Sergio Battiato
- Dipartimento di Scienze Chimiche
- Università degli Studi di Catania
- INSTM UdR-Catania
- Catania
- Italy
| | - Maria M. Giangregorio
- CNR-NANOTEC
- Istituto di Nanotecnologia
- Dipartimento di Chimica
- Università di Bari
- 70126 Bari
| | - Maria R. Catalano
- Dipartimento di Scienze Chimiche
- Università degli Studi di Catania
- INSTM UdR-Catania
- Catania
- Italy
| | - Raffaella Lo Nigro
- Istituto per la Microelettronica e Microsistemi IMM-CNR
- 95121 Catania
- Italy
| | - Maria Losurdo
- CNR-NANOTEC
- Istituto di Nanotecnologia
- Dipartimento di Chimica
- Università di Bari
- 70126 Bari
| | - Graziella Malandrino
- Dipartimento di Scienze Chimiche
- Università degli Studi di Catania
- INSTM UdR-Catania
- Catania
- Italy
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15
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Logsdail AJ, Downing CA, Keal TW, Sherwood P, Sokol AA, Catlow CRA. Modelling the chemistry of Mn-doped MgO for bulk and (100) surfaces. Phys Chem Chem Phys 2016; 18:28648-28660. [DOI: 10.1039/c6cp04622c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have investigated the energetic properties of Mn-doped MgO bulk and (100) surfaces using a QM/MM embedding computational method, calculating the formation energy for doped systems, as well as for surface defects, and the subsequent effect on chemical reactivity.
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Affiliation(s)
- Andrew J. Logsdail
- Kathleen Lonsdale Materials Chemistry
- Department of Chemistry
- University College London
- London
- UK
| | - Christopher A. Downing
- Kathleen Lonsdale Materials Chemistry
- Department of Chemistry
- University College London
- London
- UK
| | - Thomas W. Keal
- Scientific Computing Department
- STFC Daresbury Laboratory
- Warrington
- UK
| | - Paul Sherwood
- Scientific Computing Department
- STFC Daresbury Laboratory
- Warrington
- UK
| | - Alexey A. Sokol
- Kathleen Lonsdale Materials Chemistry
- Department of Chemistry
- University College London
- London
- UK
| | - C. Richard A. Catlow
- Kathleen Lonsdale Materials Chemistry
- Department of Chemistry
- University College London
- London
- UK
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16
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Plaisance CP, van Santen RA. Structure Sensitivity of the Oxygen Evolution Reaction Catalyzed by Cobalt(II,III) Oxide. J Am Chem Soc 2015; 137:14660-72. [PMID: 26479891 DOI: 10.1021/jacs.5b07779] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Quantum chemical calculations and simulated kinetics were used to examine the structure sensitivity of the oxygen evolution reaction on several surface terminations of Co3O4. Active sites consisting of two adjacent Co(IV) cations connected by bridging oxos were identified on both the (001) and (311) surfaces. Formation of the O-O bond proceeds on these sites by nucleophilic attack of water on a bridging oxo. It was found that the relative turnover frequencies for the different sites are highly dependent on the overpotential, with the dual-Co site on the (311) surface being most active at medium overpotentials (0.46-0.77 V), where O-O bond formation by water addition is rate limiting. A similar dual-Co site on the (001) surface is most active at low overpotentials (<0.46 V), where O2 release is rate limiting, and a single-Co site on the (110) surface is most active at overpotentials that are high enough (>0.77 V) to form a significant concentration of highly reactive terminal Co(V)═O species. Two overpotential-dependent Sabatier relationships were identified based on the Brønsted basicity and redox potential of the active site, explaining the change in the active site with overpotential. The (311) dual-Co site that is most active in the medium overpotential range is consistent with recent experimental observations suggesting that a defect site is responsible for the observed oxygen evolution activity and that a modest concentration of superoxo intermediates is present on the surface. Importantly, we find that it is essential to consider the kinetics of the water addition and O2 release steps rather than only the thermodynamics.
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Affiliation(s)
- Craig P Plaisance
- Institute for Complex Molecular Systems and Laboratory of Inorganic Materials Chemistry, Schuit Institute of Catalysis, Eindhoven University of Technology , 5612 AZ, Eindhoven, The Netherlands
| | - Rutger A van Santen
- Institute for Complex Molecular Systems and Laboratory of Inorganic Materials Chemistry, Schuit Institute of Catalysis, Eindhoven University of Technology , 5612 AZ, Eindhoven, The Netherlands
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17
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Ahmed MH, Torrelles X, Treacy J, Hussain H, Nicklin C, Wincott PL, Vaughan DJ, Thornton G, Lindsay R. Geometry of α-Cr 2O 3(0001) as a Function of H 2O Partial Pressure. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2015; 119:21426-21433. [PMID: 26877825 PMCID: PMC4729357 DOI: 10.1021/acs.jpcc.5b04607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 08/14/2015] [Indexed: 06/05/2023]
Abstract
Surface X-ray diffraction has been employed to elucidate the surface structure of α-Cr2O3(0001) as a function of water partial pressure at room temperature. In ultra high vacuum, following exposure to ∼2000 Langmuir of H2O, the surface is found to be terminated by a partially occupied double layer of chromium atoms. No evidence of adsorbed OH/H2O is found, which is likely due to either adsorption at minority sites, or X-ray induced desorption. At a water partial pressure of ∼30 mbar, a single OH/H2O species is found to be bound atop each surface Cr atom. This adsorption geometry does not agree with that predicted by ab initio calculations, which may be a result of some differences between the experimental conditions and those modeled.
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Affiliation(s)
- M. H.
M. Ahmed
- Corrosion
and Protection Centre, School of Materials, The University of Manchester, Sackville Street, Manchester, M13 9PL, U.K.
| | - X. Torrelles
- Institut
de Ciència de Materials de Barcelona (CSIC), Campus UAB, 08193 Bellaterra, Spain
| | - J.P.W. Treacy
- Corrosion
and Protection Centre, School of Materials, The University of Manchester, Sackville Street, Manchester, M13 9PL, U.K.
| | - H. Hussain
- London
Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - C. Nicklin
- Diamond
Light Source, Harwell Science and Innovation
Campus, Didcot, Oxfordshire, OX11 0DE, U.K.
| | - P. L. Wincott
- Williamson
Research Centre for Molecular Environmental Science and School of
Earth, Atmospheric and Environmental Sciences, The University of Manchester, M13 9PL, Manchester, U.K.
| | - D. J. Vaughan
- Williamson
Research Centre for Molecular Environmental Science and School of
Earth, Atmospheric and Environmental Sciences, The University of Manchester, M13 9PL, Manchester, U.K.
| | - G. Thornton
- London
Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - R. Lindsay
- Corrosion
and Protection Centre, School of Materials, The University of Manchester, Sackville Street, Manchester, M13 9PL, U.K.
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18
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Ončák M, Włodarczyk R, Sauer J. Water on the MgO(001) Surface: Surface Reconstruction and Ion Solvation. J Phys Chem Lett 2015; 6:2310-2314. [PMID: 26266610 DOI: 10.1021/acs.jpclett.5b00885] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The interaction of water with the MgO(001) surface under ambient conditions is investigated by density functional theory combined with statistical thermodynamics. For water loadings of more than one monolayer, we show that the standard structure model, a fully hydroxylated surface, needs to be revised. Reconstructed surfaces, involving hydrated/hydroxylated Mg(2+) ions above the surface, are more stable. These findings provide a consistent picture for surface hydroxylation between low and high water coverage that is in agreement with available XPS data.
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Affiliation(s)
- Milan Ončák
- Institut für Chemie, Humboldt-Universität zu Berlin, Unter den Linden 6, 10099 Berlin, Germany
| | - Radosław Włodarczyk
- Institut für Chemie, Humboldt-Universität zu Berlin, Unter den Linden 6, 10099 Berlin, Germany
| | - Joachim Sauer
- Institut für Chemie, Humboldt-Universität zu Berlin, Unter den Linden 6, 10099 Berlin, Germany
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19
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van Santen RA, Tranca I, Hensen EJ. Theory of surface chemistry and reactivity of reducible oxides. Catal Today 2015. [DOI: 10.1016/j.cattod.2014.07.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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20
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Erba A, Maul J, Demichelis R, Dovesi R. Assessing thermochemical properties of materials through ab initio quantum-mechanical methods: the case of α-Al2O3. Phys Chem Chem Phys 2015; 17:11670-7. [DOI: 10.1039/c5cp01537e] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Accurate ab initio calculations of thermodynamic and structural thermal properties of corundum demonstrate its quasi-harmonic nature up to the melting temperature.
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Affiliation(s)
- Alessandro Erba
- Dipartimento di Chimica and Centre of Excellence Nanostructured Interfaces and Surfaces (NIS)
- Università di Torino
- IT-10125 Torino
- Italy
| | - Jefferson Maul
- Dipartimento di Chimica and Centre of Excellence Nanostructured Interfaces and Surfaces (NIS)
- Università di Torino
- IT-10125 Torino
- Italy
- Laboratório de Combustíveis e Materiais
| | - Raffaella Demichelis
- Nanochemistry Research Institute
- Curtin Institute for Computation
- and Department of Chemistry
- Curtin University
- Perth
| | - Roberto Dovesi
- Dipartimento di Chimica and Centre of Excellence Nanostructured Interfaces and Surfaces (NIS)
- Università di Torino
- IT-10125 Torino
- Italy
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21
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Ivanova B, Spiteller M. Adsorption of uranium composites onto saltrock oxides - experimental and theoretical study. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2014; 135:75-83. [PMID: 24794043 DOI: 10.1016/j.jenvrad.2014.03.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Revised: 03/30/2014] [Accepted: 03/30/2014] [Indexed: 06/03/2023]
Abstract
The study encompassed experimental mass spectrometric and theoretical quantum chemical studies on adsorption of uranium species in different oxidation states of the metal ion, and oxides of UxOy(n+) type, where x = 1 or 3, y = 2 or 8, and n = 0, 1 or 2 onto nanosize-particles of saltrock oxides MO (M = Mg(II), Ca(II), Ni(II), Co(II), Sr(II) or Ba(II)), M2Oy (M = Au(III) or Ag(I), y = 3 or 1) silicates 3Al2O3.2SiO2, natural kaolinite (Al2O2·2SiO2·2H2O), illite (K0.78Ca0.02Na0.02(Mg0.34Al1.69Fe(III)0.02)[Si3.35Al0.65]O10(OH)2·nH2O), CaSiO3, 3MgO·4SiO2,H2O, and M(1)M(2)(SiO4)X2 (M(1) = M(2) = Al or M(1) = K, M(2) = Al, X = F or Cl), respectively. The UV-MALDI-Orbitrap mass spectrometry was utilized in solid-state and semi-liquid colloidal state, involving the laser ablation at λex = 337.2 nm. The theoretical modeling and experimental design was based on chemical-, physico-chemical, physical and biological processes involving uranium species under environmental conditions. Therefore, the results reported are crucial for quality control and monitoring programs for assessment of radionuclide migration. They impact significantly the methodology for evaluation of human health risk from radioactive contamination. The study has importance for understanding the coordination and red-ox chemistry of uranium compounds as well. Due to the double nature of uranium between rare element and superconductivity like materials as well as variety of oxidation states ∈ (+1)-(+6), the there remain challenging areas for theoretical and experimental research, which are of significant importance for management of nuclear fuel cycles and waste storage.
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Affiliation(s)
- Bojidarka Ivanova
- Lehrstuhl für Analytische Chemie, Institut für Umweltforschung, Fakultät für Chemie und Chemische Biologie, Universität Dortmund, Otto-Hahn-Strasse 6, 44221 Dortmund, Nordrhein-Westfalen, Germany.
| | - Michael Spiteller
- Lehrstuhl für Analytische Chemie, Institut für Umweltforschung, Fakultät für Chemie und Chemische Biologie, Universität Dortmund, Otto-Hahn-Strasse 6, 44221 Dortmund, Nordrhein-Westfalen, Germany
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22
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Zhou X, Hensen EJM, van Santen RA, Li C. DFT Simulations of Water Adsorption and Activation on Low-Index α-Ga2O3Surfaces. Chemistry 2014; 20:6915-26. [DOI: 10.1002/chem.201400006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Indexed: 11/08/2022]
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