1
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Macion A, Schäfer R. Ionization potentials of metal clusters studied with a broad range, tunable vacuum ultraviolet light source. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:063101. [PMID: 37862487 DOI: 10.1063/5.0151238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 05/11/2023] [Indexed: 10/22/2023]
Abstract
In this work, we present an alternative to complex laser setups or synchrotron light sources to accurately measure the ionization potentials of metal clusters. The setup is based on a commercial Xe flash lamp, combined with a vacuum monochromator, and has been applied to determine the ionization potentials of Snn clusters with n = 8-12 atoms. The uncertainty in the determination of the ionization potentials is mainly caused by the bandwidth of the monochromator. The adiabatic ionization potentials (AIPs) are extracted from experimental photoionization efficiency curves. Franck-Condon simulations are additionally used to interpret the shape and onset of the photo-ion yield. The obtained AIPs are (all energies are in eV) Sn8 (6.53 ± 0.05), Sn9 (6.69 ± 0.04), Sn10 (6.93 ± 0.03), Sn11 (6.34 ± 0.05), and Sn12 (IsoI 6.64 ± 0.04 and IsoIII 6.36 ± 0.05). Furthermore, the impact of multiple isomers present in the experiment on the photo-ion yield is addressed and compared with other experimental data in the literature.
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Affiliation(s)
- A Macion
- Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - R Schäfer
- Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
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2
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Fielicke A. Probing the binding and activation of small molecules by gas-phase transition metal clusters via IR spectroscopy. Chem Soc Rev 2023. [PMID: 37162518 DOI: 10.1039/d2cs00104g] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Isolated transition metal clusters have been established as useful models for extended metal surfaces or deposited metal particles, to improve the understanding of their surface chemistry and of catalytic reactions. For this objective, an important milestone has been the development of experimental methods for the size-specific structural characterization of clusters and cluster complexes in the gas phase. This review focusses on the characterization of molecular ligands, their binding and activation by small transition metal clusters, using cluster-size specific infrared action spectroscopy. A comprehensive overview and a critical discussion of the experimental data available to date is provided, reaching from the initial results obtained using line-tuneable CO2 lasers to present-day studies applying infrared free electron lasers as well as other intense and broadly tuneable IR laser sources.
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Affiliation(s)
- André Fielicke
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany.
- Institut für Optik und Atomare Physik, Technische Universität Berlin, 10623 Berlin, Germany
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3
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Rivic F, Lehr A, Fuchs TM, Schäfer R. Joint electric and magnetic beam deflection experiments and quantum chemical studies of MSn 12 clusters (M = Al, Ga, In): on the interplay of geometric structure and magnetic properties in nanoalloys. Faraday Discuss 2023; 242:231-251. [PMID: 36260024 DOI: 10.1039/d2fd00091a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
MSn12 clusters (M = Al, Ga, In) were studied in electric and magnetic beam deflection experiments at temperatures of 16 K and 30 K. For all three species, the results of the electric beam deflection experiments indicate the presence of two structural isomers of which one is considerably polar. The magnetic beam deflection experiments show atom-like beam splitting (superatomic behavior) with g-factors of 2.6-2.7 for a fraction of the clusters in the molecular beam, indicating significant spin-orbit coupling. On the one hand, we investigate by several experiments combining electric and magnetic deflectors how the superatomic and polar fractions are linked proving the correlation of the Stark and Zeeman effects. On the other hand, the magnetic deflection behavior is examined more thoroughly by performing quantum chemical calculations. By systematic distortion of an artificial icosahedral tin cage towards the global minimum structure, which has a pyritohedral geometry, the shifts in the magnitude of the g-factor are found to be mainly caused by a single dominant electronic excitation. This allows one to develop a semi-quantitative understanding of the magnetic behavior. On the basis of avoided crossings in the rotational Zeeman diagram, simulations of the magnetic beam deflection comprising computed rotational constants, vibrational modes, g-factors and spin-rotation coupling constants are performed which resemble our experimental findings in satisfactory agreement. With this, a better understanding of the magnetic properties of nanoalloy clusters can be achieved. However, the geometric structures of the polar isomers are still unknown.
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Affiliation(s)
- Filip Rivic
- Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany.
| | - Andreas Lehr
- Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany.
| | - Thomas M Fuchs
- Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany.
| | - Rolf Schäfer
- Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany.
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4
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Ferrari P, Kaw KA, Lievens P, Janssens E. Radiative cooling in silver and palladium doped gold clusters. Faraday Discuss 2023; 242:269-285. [PMID: 36168998 DOI: 10.1039/d2fd00090c] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The emission of photons from a thermally populated electronic excited state, via the process of recurrent fluorescence, has been recognized as a prominent cooling channel in hot molecules and small metal clusters. For the latter case, however, only monometallic species have been investigated to date. An active radiative cooling channel has a stabilizing effect and can favor the size and composition specific production of selected clusters. In this work, the influence of silver and palladium doping on the radiative cooling of gold cluster cations is studied. The quenching of metastable fragmentation due to radiation of laser-excited Aun+, AgAun-1+ and PdAun-1+ (n = 11-15) clusters is investigated in a single-pass molecular beam setup. The observed high radiation rates, with values in the range from 103 to 105 s-1, are consistent with recurrent fluorescence. The rates present a pronounced odd-even staggering with higher values for the clusters with closed-shell electronic configurations. While substitution of Au with Ag does not alter the odd-even pattern with cluster size, replacing Au with Pd shifts the pattern by one atom. The experimental observations are discussed in terms of the dissociation energy of the clusters, which sets their effective temperature during photon emission, and the low-lying electronic excited states involved in the photon emission process. Linear-response time-dependent density functional theory calculations on selected species are used to illustrate the significant effect of the electronic structure on the radiation rates. For n = 14, substitution of Au with Ag lowers the energy of the lowest-energy transition in the cluster, which in addition has a higher oscillator strength, favoring radiative cooling. The opposite effect is seen in Pd doped clusters. Based on this analysis, conclusions can be drawn about the significance of radiative cooling in laser-excited alloy clusters, with a concomitant fast stabilization at high internal energy conditions.
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Affiliation(s)
- Piero Ferrari
- Quantum Solid-State Physics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200d, Leuven 3001, Belgium.
| | - Kevin Anthony Kaw
- Quantum Solid-State Physics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200d, Leuven 3001, Belgium.
| | - Peter Lievens
- Quantum Solid-State Physics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200d, Leuven 3001, Belgium.
| | - Ewald Janssens
- Quantum Solid-State Physics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200d, Leuven 3001, Belgium.
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5
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Lehr A, Rivic F, Jäger M, Gleditzsch M, Schäfer R. Optical absorption and shape transition in neutral Sn N clusters with N ≤ 40: a photodissociation spectroscopy and electric beam deflection study. Phys Chem Chem Phys 2022; 24:11616-11635. [PMID: 35507965 DOI: 10.1039/d2cp01171a] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Neutral SnN clusters with N = 6-20, 25, 30, 40 are investigated in a joint experimental and quantum chemical study with the aim to reveal their optical absorption in conjunction with their structural evolution. Electric beam deflection and photodissociation spectroscopy are applied as molecular beam techniques at nozzle temperatures of 16 K, 32 K and 300 K. The dielectric response is probed following the approach in S. Schäfer et al., J. Phys. Chem A, 2008, 112, 12312-12319. It is improved on those findings and the cluster size range is extended in order to cover the prolate growth regime. The impact of the electric dipole moment, rotational temperature and vibrational excitation on the deflection profiles is discussed thoroughly. Photodissociation spectra of tin clusters are recorded for the first time, show similarities to spectra of silicon clusters and are demonstrated to be significantly complicated by the presence of multiphoton absorption in the low-energy region and large excess energies upon dissociation which is modelled by the RRKM theory. In both experiments two isomers for the clusters with N = 8, 11, 12, 19 need to be considered to explain the experimental results. Triple-capped trigonal prisms and double-capped square antiprisms are confirmed to be the driving building units for almost the entire size range. Three dominating fragmentation channels are observed, i.e. the loss of a tin atom for N < 12, a Sn7 fragment for N < 19 and a Sn10 fragment for N ≥ 19 with Sn15 subunits constituting recurring geometric motifs for N > 20. The prolate-to-quasispherical structural transition is found to occur at 30 < N ≤ 40 and is analyzed with respect to the observed optical behavior taking quantum chemical calculations and the Mie-Gans theory into account. Limitations of the experimental approach to study the geometric and electronic structure of the clusters at elevated temperatures due to vibrational excitation is also thoroughly discussed.
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Affiliation(s)
- Andreas Lehr
- Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany.
| | - Filip Rivic
- Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany.
| | - Marc Jäger
- Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany.
| | - Martin Gleditzsch
- Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany.
| | - Rolf Schäfer
- Technical University of Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany.
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6
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Farshad M, Perera DC, Rasaiah JC. Theoretical study of the stability, structure, and optical spectra of small silver clusters and their formation using density functional theory. Phys Chem Chem Phys 2021; 23:25507-25517. [PMID: 34698740 DOI: 10.1039/d1cp04070g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
An understanding of the mechanism of formation of small clusters would help to identify efficient routes to their synthesis. Here, we apply density functional theory (DFT) to study the free energies and structure of ultra-small silver clusters, and time-dependent density functional theory (TDDFT) to calculate their UV-Vis spectra and provide a better understanding of the intermediate steps in cluster formation in the gas phase and solution. Our calculations of the optical properties of neutral and cationic clusters confirm the presence of charged and uncharged intermediates observed in pulse radiolysis experiments during the early stages of the growth of silver clusters. The free energies of formation of hydrated clusters extracted from DFT calculations reveal the greater thermodynamic stability of cationic clusters compared to the corresponding neutral clusters of the same composition. This is consistent with the predominance of kinetically stable cationic clusters observed in pulse radiolysis experiments. Our DFT and TDDFT calculations clarify the effects of ligand, hydration, and oxidation states on the structure, stability, and optical properties of silver clusters that elucidate the mechanism of silver cluster formation in solution and the gas phase.
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Affiliation(s)
- Mohsen Farshad
- Department of Chemistry, University of Maine, Orono, Maine 04469, USA.
| | - Duwage C Perera
- Department of Chemistry, University of Maine, Orono, Maine 04469, USA.
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7
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Ferrari P, Delgado-Callico L, Lushchikova OV, Hou GL, Baletto F, Bakker JM, Janssens E. The size-dependent influence of palladium doping on the structures of cationic gold clusters. NANOSCALE ADVANCES 2021; 3:6197-6205. [PMID: 34765870 PMCID: PMC8548875 DOI: 10.1039/d1na00587a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/20/2021] [Indexed: 06/13/2023]
Abstract
The physicochemical properties of small metal clusters strongly depend on their precise geometry. Determining such geometries, however, is challenging, particularly for clusters formed by multiple elements. In this work, we combine infrared multiple photon dissociation spectroscopy and density functional theory calculations to investigate the lowest-energy structures of Pd doped gold clusters, PdAu n-1 + (n ≤ 10). The high-quality experimental spectra allow for an unambiguous determination of the structures adopted by the clusters. Our results show that the Pd-Au interaction is so large that the structures of PdAu n-1 + and Au n + are very different. Pd doping induces a 2D to 3D transition at much smaller cluster sizes than for pure Au n + clusters. PdAu n-1 + clusters are three-dimensional from n = 4, whereas for Au n + this transition only takes place at n = 7. Despite the strong Au-Pd interaction, the Au n-1 + cluster geometries remain recognizable in PdAu n-1 + up to n = 7. This is particularly clear for PdAu6 +. In PdAu8 + and PdAu9 +, Pd triggers major rearrangements of the Au clusters, which adopt pyramidal shapes. For PdAu4 + we find a geometry that was not considered in previous studies, and the geometry found for PdAu8 + does not correspond to the lowest-energy structure predicted by DFT, suggesting kinetic trapping during formation. This work demonstrates that even with the continuous improvement of computational methods, unambiguous assignment of cluster geometries still requires a synergistic approach, combining experiment and computational modelling.
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Affiliation(s)
- Piero Ferrari
- Quantum Solid-State Physics, Department of Physics and Astronomy, KU Leuven Leuven Belgium
| | | | - Olga V Lushchikova
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory Nijmegen The Netherlands
| | - Gao-Lei Hou
- Quantum Solid-State Physics, Department of Physics and Astronomy, KU Leuven Leuven Belgium
| | | | - Joost M Bakker
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory Nijmegen The Netherlands
| | - Ewald Janssens
- Quantum Solid-State Physics, Department of Physics and Astronomy, KU Leuven Leuven Belgium
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8
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Green AE, Gentleman AS, Schöllkopf W, Fielicke A, Mackenzie SR. Atomic Cluster Au_{10}^{+} Is a Strong Broadband Midinfrared Chromophore. PHYSICAL REVIEW LETTERS 2021; 127:033002. [PMID: 34328766 DOI: 10.1103/physrevlett.127.033002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 04/30/2021] [Accepted: 05/25/2021] [Indexed: 06/13/2023]
Abstract
We report an intense broadband midinfrared absorption band in the Au_{10}^{+} cluster in a region in which only molecular vibrations would normally be expected. Observed in the infrared multiple photon dissociation spectra of Au_{10}Ar^{+}, Au_{10}(N_{2}O)^{+}, and Au_{10}(OCS)^{+}, the smooth feature stretches 700-3400 cm^{-1} (λ=14-2.9 μm). Calculations confirm unusually low-energy allowed electronic excitations consistent with the observed spectra. In Au_{10}(OCS)^{+}, IR absorption throughout the band drives OCS decomposition resulting in CO loss, providing an alternative method of bond activation or breaking.
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Affiliation(s)
- Alice E Green
- Department of Chemistry, University of Oxford, Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Alexander S Gentleman
- Department of Chemistry, University of Oxford, Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Wieland Schöllkopf
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - André Fielicke
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623, Berlin, Germany
| | - Stuart R Mackenzie
- Department of Chemistry, University of Oxford, Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, United Kingdom
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9
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Silva FT, Yoshinaga M, Galvão BRL. A method for predicting basins in the global optimization of nanoclusters with applications to Al xCu y alloys. Phys Chem Chem Phys 2020; 22:16914-16925. [PMID: 32672291 DOI: 10.1039/d0cp01327g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The problem of obtaining the geometrical configuration of a molecule that minimizes its potential energy is a very complicated one for a series of applications, ranging from determining the structure of biological macromolecules to nanoclusters of atoms. Global optimization tools are available for this task, and many of them are based in performing successive local optimizations, where the starting geometries for these steps are determined by an intelligent algorithm. Here we develop a method to save computing time in the optimization of nanoclusters by predicting if a given minimum has been previously visited during local optimization steps. Our application to Cu-Al nanoalloys indicates that it is possible to save a substantial amount of computational cost. The application also reveals new promising AlxCuy clusters and explain their stabilities in terms of the jellium model.
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Affiliation(s)
- F T Silva
- Prime Systems, Av. Afonso Pena 3577, 7F, Belo Horizonte, Minas Gerais, Brazil
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10
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Ferrari P, Hou GL, Lushchikova OV, Calvo F, Bakker JM, Janssens E. The structures of cationic gold clusters probed by far-infrared spectroscopy. Phys Chem Chem Phys 2020; 22:11572-11577. [PMID: 32400803 DOI: 10.1039/d0cp01613f] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Determining the precise structures of small gold clusters is an essential step towards understanding their chemical and physical properties. Due to the relativistic nature of gold, its clusters remain planar (2D) up to appreciable sizes. Ion mobility experiments have suggested that positively charged gold clusters adopt three-dimensional (3D) structures from n = 8 onward. Computations predict, depending on the level of theory, 2D or 3D structures as putative energy-minimum for n = 8. In this work, far-infrared multiple photon dissociation spectroscopy, using Ar as tagging element, is combined with density-functional theory calculations to determine the structures of Aun+ (n≤ 9) clusters formed by laser ablation. While the Au frameworks in Au6Arm+ and Au7Arm+ complexes are confirmed to be planar and that in Au9Arm+ three-dimensional, we demonstrate the coexistence of 3D and planar Au8Arm+ (m = 1-3) isomers. Thus, it is revealed that at finite temperatures, the formal 2D to 3D transition takes place at n = 8 but is not sharp.
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Affiliation(s)
- Piero Ferrari
- KU Leuven, Department of Physics and Astronomy, Quantum Solid-State Physics, 3001 Leuven, Belgium.
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11
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Jäger M, Schneider J, Schäfer R. Size- and Charge-Dependent Optoelectronic Properties of CdSe Clusters: Evolution of the Optical Gap from Molecular to Bulk Behavior. J Phys Chem A 2020; 124:185-196. [DOI: 10.1021/acs.jpca.9b10401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marc Jäger
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - Jurek Schneider
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - Rolf Schäfer
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
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12
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Galvão BRL, Viegas LP. What Electronic Structure Method Can Be Used in the Global Optimization of Nanoclusters? J Phys Chem A 2019; 123:10454-10462. [DOI: 10.1021/acs.jpca.9b09309] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Breno R. L. Galvão
- Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG, Av. Amazonas 5253, 30421-169 Belo Horizonte, Minas Gerais, Brazil
| | - Luís P. Viegas
- Aarhus Institute of Advanced Studies, Aarhus University, Aarhus DK-8000, Denmark
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13
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Förstel M, Schewe W, Dopfer O. Optical Spectroscopy of the Au 4
+
Cluster: The Resolved Vibronic Structure Indicates an Unexpected Isomer. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201813094] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marko Förstel
- Institut für Optik und Atomare Physik; Technische Universität Berlin; Hardenbergstr. 36 10623 Berlin Germany
| | - Wolfgang Schewe
- Institut für Optik und Atomare Physik; Technische Universität Berlin; Hardenbergstr. 36 10623 Berlin Germany
| | - Otto Dopfer
- Institut für Optik und Atomare Physik; Technische Universität Berlin; Hardenbergstr. 36 10623 Berlin Germany
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14
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Förstel M, Schewe W, Dopfer O. Optical Spectroscopy of the Au4
+
Cluster: The Resolved Vibronic Structure Indicates an Unexpected Isomer. Angew Chem Int Ed Engl 2019; 58:3356-3360. [DOI: 10.1002/anie.201813094] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/14/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Marko Förstel
- Institut für Optik und Atomare Physik; Technische Universität Berlin; Hardenbergstr. 36 10623 Berlin Germany
| | - Wolfgang Schewe
- Institut für Optik und Atomare Physik; Technische Universität Berlin; Hardenbergstr. 36 10623 Berlin Germany
| | - Otto Dopfer
- Institut für Optik und Atomare Physik; Technische Universität Berlin; Hardenbergstr. 36 10623 Berlin Germany
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15
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Fernández E, Boronat M. Sub nanometer clusters in catalysis. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:013002. [PMID: 30499451 DOI: 10.1088/1361-648x/aaed84] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Sub nanometer transition metal clusters composed of a small number of atoms exhibit unexpected electronic, optical, magnetic and catalytic properties that often change substantially as a function of cluster atomicity. Several factors influence their unique catalytic behavior, including their discrete electronic structure of molecular-like orbitals and the accessibility of their low-coordinated atoms. In addition, these factors are strongly correlated so that changes in their morphology may provoke large modifications to their electronic structure and vice versa. The thermodynamic instability of clusters makes it necessary to stabilize them with protective ligands in solution or to support them on solid matrices for practical applications, which introduces non-negligible modifications into their properties. Understanding their cause and extent is the key point to potentially achieve a fine tuning of their catalytic behavior. Selected examples are discussed illustrating important points on this matter, such as the influence of cluster morphology on reactivity, the need of anchoring clusters to avoid sintering and deactivation, and the possible formation of clusters in solution or under reaction conditions, with the associated difficulty to identify them as the true active species.
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Affiliation(s)
- Estefanía Fernández
- Instituto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, Avda. de los Naranjos s/n, 46022 Valencia, Spain
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16
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Jäger M, Shayeghi A, Klippenstein V, Johnston RL, Schäfer R. Chemical bonding in initial building blocks of semiconductors: Geometrical structures and optical absorption spectra of isolated CdSe2+ and Cd2Se2+ species. J Chem Phys 2018; 149:244308. [DOI: 10.1063/1.5066414] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Affiliation(s)
- Marc Jäger
- Technische Universität Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - Armin Shayeghi
- Technische Universität Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - Viktor Klippenstein
- Technische Universität Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - Roy L. Johnston
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Rolf Schäfer
- Technische Universität Darmstadt, Eduard-Zintl-Institut, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
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17
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Shayeghi A, Pašteka LF, Götz DA, Schwerdtfeger P, Schäfer R. Spin–orbit effects in optical spectra of gold–silver trimers. Phys Chem Chem Phys 2018; 20:9108-9114. [DOI: 10.1039/c8cp00672e] [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
Photodissociation spectra of cationic gold–silver trimers are analysed using relativistic electronic structure theories paying special attention to the importance of spin–orbit and charge transfer effects.
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Affiliation(s)
- A. Shayeghi
- Vienna Center for Quantum Science and Technology
- Faculty of Physics
- University of Vienna
- A-1090 Vienna
- Austria
| | - L. F. Pašteka
- Centre for Theoretical Chemistry and Physics
- The New Zealand Institute for Advanced Study
- Massey University Auckland
- 0632 Auckland
- New Zealand
| | - D. A. Götz
- Eduard-Zintl-Institut
- Technische Universität Darmstadt
- 64287 Darmstadt
- Germany
| | - P. Schwerdtfeger
- Centre for Theoretical Chemistry and Physics
- The New Zealand Institute for Advanced Study
- Massey University Auckland
- 0632 Auckland
- New Zealand
| | - R. Schäfer
- Eduard-Zintl-Institut
- Technische Universität Darmstadt
- 64287 Darmstadt
- Germany
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18
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Förstel M, Jaeger BKA, Schewe W, Sporkhorst PHA, Dopfer O. Improved tandem mass spectrometer coupled to a laser vaporization cluster ion source. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:123110. [PMID: 29289197 DOI: 10.1063/1.5010853] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We describe two improvements to an existing tandem mass spectrometer coupled to a laser vaporization cluster ion source suitable for photodissociation spectroscopy: (i) cooling of the cluster source nozzle and (ii) mass selection prior to the photodissociation region via replacing an octupole ion guide by a quadrupole mass spectrometer. The improved sensitivity and transmission enable the production of larger heteroatomic clusters as well as rare gas solvated clusters. We present two examples demonstrating the new capabilities of the improved setup. In the first application, cooling of the cluster source nozzle produces Si+Arn and Si2+Arn cluster cations with n = 1-25. Magic numbers are extracted from the mass spectrum by applying a transmission function obtained via simulations. In the second example, the vibronic photodissociation spectrum of cold Au4+ cluster ions is recorded with unprecedented detail, resolution, and sensitivity. Such high-resolution optical excitation spectra of metal cluster cations may serve as a benchmark for the performance of Franck-Condon simulations based on quantum chemical calculations for excited states.
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Affiliation(s)
- Marko Förstel
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Berlin, Germany
| | - Bertram K A Jaeger
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Berlin, Germany
| | - Wolfgang Schewe
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Berlin, Germany
| | - Philipp H A Sporkhorst
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Berlin, Germany
| | - Otto Dopfer
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Berlin, Germany
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19
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van der Tol J, Jia D, Li Y, Chernyy V, Bakker JM, Nguyen MT, Lievens P, Janssens E. Structural assignment of small cationic silver clusters by far-infrared spectroscopy and DFT calculations. Phys Chem Chem Phys 2017; 19:19360-19368. [DOI: 10.1039/c7cp03335d] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The structures of cationic silver clusters Agn+ (n = 3–13) are investigated by comparing measured far-IR photodissociation spectra of cluster–argon complexes with calculated harmonic vibrational spectra.
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Affiliation(s)
- Johan van der Tol
- Laboratory of Solid State Physics and Magnetism
- KU Leuven
- B-3001 Leuven
- Belgium
| | - Dewei Jia
- Laboratory of Solid State Physics and Magnetism
- KU Leuven
- B-3001 Leuven
- Belgium
| | - Yejun Li
- Laboratory of Solid State Physics and Magnetism
- KU Leuven
- B-3001 Leuven
- Belgium
- Hunan Key Laboratory of Super Microstructure and Ultrafast Process
| | - Valeriy Chernyy
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | - Joost M. Bakker
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | | | - Peter Lievens
- Laboratory of Solid State Physics and Magnetism
- KU Leuven
- B-3001 Leuven
- Belgium
| | - Ewald Janssens
- Laboratory of Solid State Physics and Magnetism
- KU Leuven
- B-3001 Leuven
- Belgium
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20
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Chaves AS, Piotrowski MJ, Da Silva JLF. Evolution of the structural, energetic, and electronic properties of the 3d, 4d, and 5d transition-metal clusters (30 TMn systems for n = 2–15): a density functional theory investigation. Phys Chem Chem Phys 2017; 19:15484-15502. [DOI: 10.1039/c7cp02240a] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Subnanometric transition-metal (TM) clusters have attracted great attention due to their unexpected physical and chemical properties, leastwise compared to their bulk counterparts.
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Affiliation(s)
- Anderson S. Chaves
- Gleb Wataghin Institute of Physics
- University of Campinas
- Campinas
- Brazil
- São Carlos Institute of Chemistry
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21
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Shayeghi A, Schäfer R, Rayner DM, Johnston RL, Fielicke A. Charge-induced dipole vs. relativistically enhanced covalent interactions in Ar-tagged Au-Ag tetramers and pentamers. J Chem Phys 2015; 143:024310. [PMID: 26178108 DOI: 10.1063/1.4923255] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Vibrational spectra of Au(n)Ag(m)(+)⋅Ar(k) (n + m = 4, 5; k = 1-4) clusters are determined by far-infrared resonant multiple photon dissociation spectroscopy in the range ν̃=100-250 cm(-1). The experimental spectra are assigned using density functional theory for geometries obtained by the Birmingham cluster genetic algorithm. Putative global minimum candidates of the Ar complexes are generated by adding Ar atoms to the Au(n)Ag(m)(+) low energy isomers and subsequent local optimization. Differential Ar binding energies indicate exceptionally strong Au-Ar bonds in Au-rich clusters, leading to fundamental changes to the IR spectra. The stronger Ar binding is attributed to a relativistically enhanced covalent character of the Au-Ar bond, while in Au-rich species charge-induced dipole interactions overcompensate the relativistic affinity to Au. Moreover, not only the absolute composition but also the topologies are essential in the description of Ar binding to a certain cluster.
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Affiliation(s)
- A Shayeghi
- Eduard-Zintl-Institut, Technische Universität Darmstadt, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - R Schäfer
- Eduard-Zintl-Institut, Technische Universität Darmstadt, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - D M Rayner
- National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
| | - R L Johnston
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - A Fielicke
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
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22
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Kaydashev VE, Janssens E, Lievens P. Optical absorption spectra of palladium doped gold cluster cations. J Chem Phys 2015; 142:034310. [PMID: 25612712 DOI: 10.1063/1.4906072] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Photoabsorption spectra of gas phase Au(n)(+) and Au(n-1)Pd(+) (13 ≤ n ≤ 20) clusters were measured using mass spectrometric recording of wavelength dependent Xe messenger atom photodetachment in the 1.9-3.4 eV photon energy range. Pure cationic gold clusters consisting of 15, 17, and 20 atoms have a higher integrated optical absorption cross section than the neighboring sizes. It is shown that the total optical absorption cross section increases with size and that palladium doping strongly reduces this cross section for all investigated sizes and in particular for n = 14-17 and 20. The largest reduction of optical absorption upon Pd doping is observed for n = 15.
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Affiliation(s)
- Vladimir E Kaydashev
- Laboratory of Solid State Physics and Magnetism, KU Leuven, Celestijnenlaan 200d - Box 2414, B-3001 Leuven, Belgium
| | - Ewald Janssens
- Laboratory of Solid State Physics and Magnetism, KU Leuven, Celestijnenlaan 200d - Box 2414, B-3001 Leuven, Belgium
| | - Peter Lievens
- Laboratory of Solid State Physics and Magnetism, KU Leuven, Celestijnenlaan 200d - Box 2414, B-3001 Leuven, Belgium
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23
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Shayeghi A, Johnston RL, Schäfer R. Communication: Global minimum search of Ag 10+ with molecular beam optical spectroscopy. J Chem Phys 2014; 141:181104. [DOI: 10.1063/1.4901109] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- A. Shayeghi
- Eduard-Zintl-Institut, Technische Universität Darmstadt, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - R. L. Johnston
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - R. Schäfer
- Eduard-Zintl-Institut, Technische Universität Darmstadt, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
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24
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Chaves AS, Rondina GG, Piotrowski MJ, Tereshchuk P, Da Silva JLF. The Role of Charge States in the Atomic Structure of Cun and Ptn (n = 2–14 atoms) Clusters: A DFT Investigation. J Phys Chem A 2014; 118:10813-21. [DOI: 10.1021/jp508220h] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
| | | | - Maurício J. Piotrowski
- Departamento
de Física, Universidade Federal de Pelotas, Caixa Postal 354, 96010-900 Pelotas, Rio Grande
do Sul, Brazil
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25
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Heard CJ, Heiles S, Vajda S, Johnston RL. Pd(n)Ag(4-n) and Pd(n)Pt(4-n) clusters on MgO (100): a density functional surface genetic algorithm investigation. NANOSCALE 2014; 6:11777-11788. [PMID: 25158024 DOI: 10.1039/c4nr03363a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The novel surface mode of the Birmingham Cluster Genetic Algorithm (S-BCGA) is employed for the global optimisation of noble metal tetramers upon an MgO (100) substrate at the GGA-DFT level of theory. The effect of element identity and alloying in surface-bound neutral subnanometre clusters is determined by energetic comparison between all compositions of PdnAg(4-n) and PdnPt(4-n). While the binding strengths to the surface increase in the order Pt > Pd > Ag, the excess energy profiles suggest a preference for mixed clusters for both cases. The binding of CO is also modelled, showing that the adsorption site can be predicted solely by electrophilicity. Comparison to CO binding on a single metal atom shows a reversal of the 5σ-d activation process for clusters, weakening the cluster-surface interaction on CO adsorption. Charge localisation determines homotop, CO binding and surface site preferences. The electronic behaviour, which is intermediate between molecular and metallic particles allows for tunable features in the subnanometre size range.
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Affiliation(s)
- Christopher J Heard
- Department of Applied Physics, Chalmers University of Technology, SE 412-96 Gothenburg, Sweden
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26
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Shayeghi A, Heard CJ, Johnston RL, Schäfer R. Optical and electronic properties of mixed Ag-Au tetramer cations. J Chem Phys 2014; 140:054312. [PMID: 24511945 DOI: 10.1063/1.4863443] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We present experimental and theoretical studies of the optical response of mixed Ag(n)Au(+)(4-n) (n=1-3) clusters in the photon energy range ℏω = 1.9-3.5 eV. Absorption spectra are recorded by a newly built longitudinal molecular beam depletion spectroscopy apparatus providing lower limits to absolute photodissociation cross sections. The experimental data are compared to optical response calculations in the framework of long-range corrected time-dependent density functional theory with initial cluster geometries obtained by the unbiased Birmingham Cluster Genetic Algorithm coupled with density functional theory. Experiments and excited state calculations shed light on the structural and electronic properties of the mixed Ag-Au tetramer cations.
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Affiliation(s)
- A Shayeghi
- Eduard-Zintl-Institut, Technische Universität Darmstadt, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
| | - C J Heard
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - R L Johnston
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - R Schäfer
- Eduard-Zintl-Institut, Technische Universität Darmstadt, Alarich-Weiss-Straße 8, 64287 Darmstadt, Germany
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27
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Rohrmann U, Schwerdtfeger P, Schäfer R. Atomic domain magnetic nanoalloys: interplay between molecular structure and temperature dependent magnetic and dielectric properties in manganese doped tin clusters. Phys Chem Chem Phys 2014; 16:23952-66. [DOI: 10.1039/c4cp02994a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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28
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Anak B, Bencharif M, Rabilloud F. Time-dependent density functional study of UV-visible absorption spectra of small noble metal clusters (Cun, Agn, Aun, n = 2–9, 20). RSC Adv 2014. [DOI: 10.1039/c3ra47244b] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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29
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Heard CJ, Johnston RL. A theoretical study of the structures and optical spectra of helical copper–silver clusters. Phys Chem Chem Phys 2014; 16:21039-48. [DOI: 10.1039/c3cp55507k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Optical response spectra of AgnCu13−n+ Bernal spiral clusters show subtle variations by dopant site and loading. Comparison to nanorod-like and icosahedral clusters shows local geometry plays a significant role in electronic transitions at the sub-nanoscale.
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