| 1. |
- Tchaplyguine, Maxim, et al.
(författare)
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Core-shell structure disclosed in self-assembled Cu-Ag nanoalloy particles.
- 2013
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 138:10
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Tidskriftsartikel (refereegranskat)abstract
- Core-shell segregation of copper and silver in self-assembled, free nanoparticles is established by means of photoelectron spectroscopy in a wide range of relative Cu-Ag concentrations. These conclusions are based on the analysis of the photon-energy-dependent changes of the Cu 3d and Ag 4d photoelectron spectra. The nanoparticles are formed from mixed Cu-Ag atomic vapor created by magnetron sputtering of a bimetallic sample in a gas-aggregation cluster source. Even at similar Cu and Ag fractions in the primary vapor the surface of the nanoparticles is dominated by silver. Only at low Ag concentration copper appears on the surface of nanoparticles. For the latter case, a threefold decrease in the Ag 4d spin-orbit splitting has been detected. The specific component distribution and electronic structure changes are discussed in connection with the earlier results on Cu-Ag macroscopic and surface alloys.
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| 2. |
- Andersson, Tomas, et al.
(författare)
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Photon energy influence on valence photoelectron spectra of silver clusters
- 2012
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 388:15, s. 152028-
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Tidskriftsartikel (refereegranskat)abstract
- Silver clusters in the size range of ∼102 constituent atoms have been studied using photoelectron spec-troscopy. The 5s and 4d valence bands have been probed with 40 and 60.5 eV photon energies. Differences in the valence band spectral features have been observed and are discussed in view of earlier results on copper clusters and in terms of differences in mean free path for electrons of different energies.
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| 3. |
- Andersson, Tomas, et al.
(författare)
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Plasmon single- and multi-quantum excitation in free metal clusters as seen by photoelectron spectroscopy
- 2011
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 134:9, s. 094511-
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Tidskriftsartikel (refereegranskat)abstract
- Plasmons are investigated in free nanoscale Na, Mg, and K metal clusters using synchrotron radiation-based x-ray photoelectron spectroscopy. The core levels for which the response from bulk and surface atoms can be resolved are probed over an extended binding energy range to include the plasmon loss features. In all species the features due to fundamental plasmons are identified, and in Na and K also those due to either the first order plasmon overtones or sequential plasmon excitation are observed. These features are discussed in view of earlier results for planar macroscopic samples and free clusters of the same materials.
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| 4. |
- Andersson, Tomas, et al.
(författare)
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The electronic structure of free aluminum clusters: Metallicity and plasmons
- 2012
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 136:20
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of free aluminum clusters with similar to 3-4 nm radius has been investigated using synchrotron radiation-based photoelectron and Auger electron spectroscopy. A beam of free clusters has been produced using a gas-aggregation source. The 2p core level and the valence band have been probed. Photoelectron energy-loss features corresponding to both bulk and surface plasmon excitation following photoionization of the 2p level have been observed, and the excitation energies have been derived. In contrast to some expectations, the loss features have been detected at energies very close to those of the macroscopic solid. The results are discussed from the point of view of metallic properties in nanoparticles with a finite number of constituent atoms. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4718362]
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| 5. |
- Jiao, Xingxing, et al.
(författare)
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Crumpled Nitrogen-Doped Graphene-Wrapped Phosphorus Composite as a Promising Anode for Lithium-Ion Batteries
- 2019
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 11:34, s. 30858-30864
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Tidskriftsartikel (refereegranskat)abstract
- Red phosphorus (P) has recently gained wide attention because of the high theoretical capacity of 2596 mA h/g, which has been regarded as promising anode material for lithium-ion batteries (LIBs). However, the actual application of red P in LIBs is hampered by the huge expansion of volume and low electronic conductivity. Herein, we design a kind of red phosphorus/crumpled nitrogen-doped graphene (P/CNG) nanocomposites with high capacity density and great rate performance as anode material for LIBs. This anode material was rationally fabricated through the scalable ball-milling method. The nanocomposite structure of P/CNG improves the electron conductivity and alleviates volume change of raw red P because of the three-dimension (3D) framework, massive defects and active sites of CNG sheets. As expected, the P/CNG composite shows excellent electrochemical performances, including high capacity (2522.6 mA h/g at 130 mA/g), remarkable rate capability (1340.5 mA h/g at 3900 mA/g), and great cyclability (1470.1 mA h/g at 1300 mA/g for 300 cycles). This work may provide a broad prospect for a great rate performance of P-based anode material for LIBs.
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| 6. |
- Mikkela, M. -H., et al.
(författare)
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Size-dependent study of Rb and K clusters using core and valence level photoelectron spectroscopy
- 2011
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Ingår i: European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 64:2-3, s. 347-352
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Tidskriftsartikel (refereegranskat)abstract
- Electronic structure of free and neutral Rb and K clusters containing from few tens to few hundred atoms has been studied using synchrotron radiation. Core-level photoelectron spectroscopy has been used to probe the metallic nature of Rb and K clusters. We show that the metallicity exists down to the dimensions of few nanometers. Simultaneously the emergence and evolution of the valence band structure has been monitored by the valence-level photoelectron spectroscopy.
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| 7. |
- Partanen, Leena, et al.
(författare)
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Solvation at nanoscale : alkali halides in water clusters
- 2013
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 138:4, s. 044301-
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Tidskriftsartikel (refereegranskat)abstract
- The solvation of alkali-halides in water clusters at nanoscale is studied by photoelectron spectroscopy using synchrotron radiation. The Na 2p, K 3p, Cl 2p, Br 3d, and I 4d core level binding energies have been measured for salt-containing water clusters. The results have been compared to those of alkali halide clusters and the dilute aqueous salt solutions. It is found that the alkali halides dissolve in small water clusters as ions.
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| 8. |
- Tchaplyguine, Maxim, et al.
(författare)
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Ag-Cu oxide nanoparticles with high oxidation states : towards new high T-c materials
- 2018
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 47:46, s. 16660-16667
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Tidskriftsartikel (refereegranskat)abstract
- In Ag-Cu oxides possible to fabricate so far, superconductivity has not been detected, but high conductivity was. In the quest for superconductivity the demand is to create a high and peculiar copper-oxygen coordination. Such coordination makes it non-trivial to determine Cu oxidation states, which may be several and co-existing. Another reason for uncertainty is in oxygen deficiency typical for superconducting crystals. Finally, Cu oxidation is influenced by the other metals in the substance. For chemical fabrication the difficulty is to tune the relative abundances of elements in a fine way. Ag-Cu oxides have been also produced by reactive co-sputtering of Cu and Ag, but the composition with high Cu oxidation states necessary for high conductivity has not been realized. In the present work we have fabricated Ag-Cu-oxide nanoparticles containing Cu and Ag in high oxidation states actual for superconductivity. The fabrication includes reactive sputtering of Ag and Cu metals, their vapour oxidation and aggregation into nanoparticles. The ability to create different and high oxidation states, also co-existing, is demonstrated. The fabrication approach also allows overcoming the poor miscibility of Cu and Ag. The nanoparticle composition and the oxidation states could be determined due to an experimental arrangement in which photoelectron spectroscopy is applied to free nanoparticles in a beam in vacuum, what allows avoiding any contact of the particles to a substrate or atmosphere. The combination of the fabrication and characterization methods has proven to be a powerful approach when fine composition tuning and control are desirable.
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| 9. |
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| 10. |
- Tchaplyguine, Maxim, et al.
(författare)
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Core-shell structure disclosed in self-assembled Cu-Ag nanoalloy particles—explanation for enhanced catalytic activity?
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Core-shell segregation of copper and silver in self-assembled, free nanoparticles is established by means of electron spectroscopy using different photon energies. The nanoparticles are formed from metal-atom mixed vapor created by sputtering of a bimetallic sample. Even at dominating copper concentration in the primary vapor the surface of the nanoparticles is composed of only silver. These conclusions are based on the analysis of the photon-energy-dependent changes of the Cu 3d and Ag 4d photoelectron spectra. The role of such segregation is discussed in connection to the suggested enhanced catalytic properties of Cu-Ag nanoparticles.
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