1
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Iwe N, Raspe K, Martinez F, Schweikhard L, Meiwes-Broer KH, Tiggesbäumker J. Metal cluster plasmons analyzed by energy-resolved photoemission. Phys Chem Chem Phys 2023; 25:1677-1684. [PMID: 36541268 DOI: 10.1039/d2cp03830g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The optical response of size-selected metal clusters is studied by wavelength-dependent photoemission and energy-resolved photoelectron detection. Relative photodetachment cross sections giving information on the plasmon are determined for the example of closed-shell Ag91-. Notably, the peak energy of this anion (3.74 eV) is higher than the small particle limit in Mie theory of 3.5 eV. Different methods to extract cross sections from the spectra are applied. In particular, we compare the results obtained by integrating the full electron yields to analyses based on evaluating specified binding energy windows. The approach opens up new possibilities to conduct studies on Landau fragmentation as a result of multielectron excitations.
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Affiliation(s)
- N Iwe
- Institute of Physics, University of Rostock, 18059, Rostock, Germany.
| | - K Raspe
- Institute of Physics, University of Rostock, 18059, Rostock, Germany.
| | - F Martinez
- Institute of Physics, University of Rostock, 18059, Rostock, Germany.
| | - L Schweikhard
- Institute of Physics, University of Greifswald, 17489, Greifswald, Germany
| | - K-H Meiwes-Broer
- Institute of Physics, University of Rostock, 18059, Rostock, Germany. .,Department Life, Light and Matter, University of Rostock, 18059, Rostock, Germany
| | - J Tiggesbäumker
- Institute of Physics, University of Rostock, 18059, Rostock, Germany. .,Department Life, Light and Matter, University of Rostock, 18059, Rostock, Germany
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2
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Messner R, Ernst WE, Lackner F. Shell-Isolated Au Nanoparticles Functionalized with Rhodamine B Fluorophores in Helium Nanodroplets. J Phys Chem Lett 2021; 12:145-150. [PMID: 33315408 PMCID: PMC7812593 DOI: 10.1021/acs.jpclett.0c03399] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 12/07/2020] [Indexed: 05/08/2023]
Abstract
Nanoparticles consisting of three different materials in a layered core@shell@shell structure are synthesized in cold helium droplets by sequential doping. Upon the formation of Au core particles, a first shell layer is formed by adding either Ar, isopropyl alcohol, or hexane. Subsequently, the droplets are doped with rhodamine B (RB) molecules; fluorescence spectra recorded upon laser excitation at 532 nm provide insight into the structure of the formed complexes. For the two-component Au@RB system, the RB fluorescence is quenched in the presence of the Au core. If an intermediate isolating shell layer is introduced (Au@shell@RB), the fluorescence increases again. The results demonstrate that shell-isolated nanoparticles can be formed inside He nanodroplets and functionalized in situ with additional molecules. As the structure of the particles depends on the pickup sequence, the approach can be exploited for the synthesis and investigation of a large variety of different combinations of plasmonic metals, intermediate layers, and molecules.
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Affiliation(s)
- Roman Messner
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria/EU
| | - Wolfgang E. Ernst
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria/EU
| | - Florian Lackner
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria/EU
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3
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Ernst WE, Hauser AW. Metal clusters synthesized in helium droplets: structure and dynamics from experiment and theory. Phys Chem Chem Phys 2020; 23:7553-7574. [PMID: 33057510 DOI: 10.1039/d0cp04349d] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Metal clusters have drawn continuous interest because of their high potential for the assembly of matter with special properties that may significantly differ from the corresponding bulk. Controlled combination of particular elements in one nanoparticle can increase the options for the creation of new materials for photonic, catalytic, or electronic applications. Superfluid helium droplets provide confinement and ultralow temperature, i.e. an ideal environment for the atom-by-atom aggregation of a new nanoparticle. This perspective presents a review of the current research progress on the synthesis of tailored metal and metal oxide clusters including core-shell designs, their characterization within the helium droplet beam, deposition on various solid substrates, and analysis via surface diagnostics. Special attention is given to the thermal properties of mixed metal clusters and questions about alloy formation on the nanoscale. Experimental results are accompanied by theoretical approaches employing computational chemistry, molecular dynamics simulations and He density functional theory.
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Affiliation(s)
- Wolfgang E Ernst
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria.
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4
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González-Lezana T, Echt O, Gatchell M, Bartolomei M, Campos-Martínez J, Scheier P. Solvation of ions in helium. INT REV PHYS CHEM 2020. [DOI: 10.1080/0144235x.2020.1794585] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Tomás González-Lezana
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
- Department of Physics, University of New Hampshire, Durham, NH, USA
| | - Michael Gatchell
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - Massimiliano Bartolomei
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - José Campos-Martínez
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas IFF-CSIC, Madrid, Spain
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Innsbruck, Austria
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5
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Cirri A, Hernández HM, Johnson CJ. High Precision Electronic Spectroscopy of Ligand-Protected Gold Nanoclusters: Effects of Composition, Environment, and Ligand Chemistry. J Phys Chem A 2020; 124:1467-1479. [PMID: 31916764 DOI: 10.1021/acs.jpca.9b09164] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Atomically precise gold nanoclusters (AuNCs) are a class of nanomaterials valued for their electronic properties and diverse structural features. While the advent of X-ray crystallography of AuNCs has revealed their geometric structures with high precision, detailed electronic structure analysis is challenged by environmental, compositional, and thermal averaging effects present in electronic spectra of typical samples. To circumvent these challenges, we have adapted mass spectrometer-based electronic absorption spectroscopy techniques to acquire high-resolution electronic spectra of atomically precisely defined nanoclusters separated from a synthetic mixture. Here we discuss recent results using this approach to link the surface chemistry of triphenylphosphine-protected AuNCs to their electronic structure and expand on key elements of the experiment and the link between these gas-phase measurements and solution-phase behavior of AuNCs. Chemically derivatized Au8(P(p-X-Ph)3)72+ and Au9(P(p-X-Ph)3)83+ clusters, where X = -H, -CH3, or -OCH3, are used to derive systematic trends in the response of the electronic spectrum to the electron-donating character of the ligand shell. We find a linear relationship between the substituent Hammett parameter σp and the transition energy between both sets of clusters' highest occupied and lowest unoccupied molecular orbitals, a transition that is localized in the metal core within the limits of the superatomic model. The similarity of the mass-selective and solution-phase UV/vis spectra of Au9(PPh3)83+ indicates that the interpretation of these experiments is transferable to the condensed phase. He and N2 environments are introduced to a series of isovalent clusters as a subtle probe of discrete environmental effects over electronic structure. Strikingly, select bands in the UV/vis spectrum respond strongly to the identity of the environment, which we interpret as a state-selective indicator of interfacially relevant electronic transitions. Physically predictable trends such as these will aid in building molecular design principles necessary for the development of novel materials based on nanoclusters.
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Affiliation(s)
- Anthony Cirri
- Department of Chemistry , Stony Brook University , 100 Nicolls Road , Stony Brook , New York 11794-3400 , United States
| | - Hanna Morales Hernández
- Department of Chemistry , Stony Brook University , 100 Nicolls Road , Stony Brook , New York 11794-3400 , United States
| | - Christopher J Johnson
- Department of Chemistry , Stony Brook University , 100 Nicolls Road , Stony Brook , New York 11794-3400 , United States
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6
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Mahmoodi-Darian M, Martini P, Tiefenthaler L, Kočišek J, Scheier P, Echt O. Solvation of Silver Ions in Noble Gases He, Ne, Ar, Kr, and Xe. J Phys Chem A 2019; 123:10426-10436. [PMID: 31725298 DOI: 10.1021/acs.jpca.9b09496] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We use a novel technique to solvate silver cations in small clusters of noble gases. The technique involves the formation of large, superfluid helium nanodroplets that are subsequently electron ionized, mass-selected by deflection in an electric field, and doped with silver atoms and noble gases (Ng) in pickup cells. Excess helium is then stripped from the doped nanodroplets by multiple collisions with helium gas at room temperature, producing cluster ions that contain no more than a few dozen noble gas atoms and just a few (or no) silver atoms. Under gentle stripping conditions, helium atoms remain attached to the cluster ions, demonstrating their low vibrational temperature. Under harsher stripping conditions, some of the heavier noble gas atoms will be evaporated as well, thus enriching stable clusters of NgnAgm+ at the expense of less stable ones. This results in local anomalies in the cluster ion abundance, which is measured in a high-resolution time-of-flight mass spectrometer. On the basis of these data, we identify specific "magic" sizes n of particularly stable ions. There is no evidence, however, for enhanced stability of Ng2Ag+, in contrast to the high stability of Ng2Au+ that derives from the covalent nature of the bond for heavy noble gases. "Magic" sizes are also identified for Ag2+ dimer ions complexed with He or Kr. Structural models will be tentatively proposed. A sequence of magic numbers n = 12, 32, and 44, indicative of three concentric solvation shells of icosahedral symmetry, is observed for HenH2O+.
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Affiliation(s)
| | - Paul Martini
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Innsbruck A-6020 , Austria
| | - Lukas Tiefenthaler
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Innsbruck A-6020 , Austria
| | - Jaroslav Kočišek
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Innsbruck A-6020 , Austria.,J. Heyrovský Institute of Physical Chemistry of the CAS , Prague 18223 , Czech Republic
| | - Paul Scheier
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Innsbruck A-6020 , Austria
| | - Olof Echt
- Institut für Ionenphysik und Angewandte Physik , Universität Innsbruck , Innsbruck A-6020 , Austria.,Department of Physics , University of New Hampshire , Durham , New Hampshire 03824 , United States
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7
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Die D, Shen XY, Song CY, Du Q. The puzzling optical-absorption and photoelectron spectra of neutral and anionic Ag 8 clusters. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2019; 206:535-537. [PMID: 30179796 DOI: 10.1016/j.saa.2018.08.056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 08/27/2018] [Indexed: 06/08/2023]
Abstract
The optical absorption and photoelectron spectra (PES) of neutral and anionic Ag8 clusters have been studied using the particle-swarm optimization technique and time-dependent density functional theory. The results demonstrate that the enigmatic optical-absorption spectrum of neutral Ag8 cluster is derived from the ground state structure with Td symmetry rather than the almost degenerate isomer with D2d symmetry. The transitions at 3.57-3.65 eV should be ascribed to the neutral fragment cluster Ag7. Meantime, the optical-absorption and PES of neutral and anionic Ag8 cluster are for the first time given a reasonable unified explanation.
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Affiliation(s)
- Dong Die
- School of Science, Xihua University, Chengdu 610039, China.
| | - Xu-Ying Shen
- School of Science, Xihua University, Chengdu 610039, China
| | - Chong-Yao Song
- School of Science, Xihua University, Chengdu 610039, China
| | - Quan Du
- School of Science, Xihua University, Chengdu 610039, China
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8
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García-Cruz R, Poulain E, Hernández-Pérez I, Reyes-Nava JA, González-Torres JC, Rubio-Ponce A, Olvera-Neria O. Effect of Spin Multiplicity in O2 Adsorption and Dissociation on Small Bimetallic AuAg Clusters. J Phys Chem A 2017; 121:6079-6089. [DOI: 10.1021/acs.jpca.7b01968] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Raúl García-Cruz
- Área
de Física Atómica Molecular Aplicada (FAMA), CBI, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa
Tamaulipas, Ciudad de México, C.P. 02200, México
| | - Enrique Poulain
- Área
de Física Atómica Molecular Aplicada (FAMA), CBI, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa
Tamaulipas, Ciudad de México, C.P. 02200, México
| | - Isaías Hernández-Pérez
- Química
de Materiales, CBI, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa Tamaulipas, Ciudad de México, C.P. 02200, México
| | - Juan A. Reyes-Nava
- Centro
de Investigación y Desarrollo Tecnológico en Energı́as Renovables, Universidad de Ciencias y Artes de Chiapas, Libramiento Norte Poniente No. 1150,
Col. Lajas Maciel, Tuxtla Gutiérrez, Chiapas, C.P. 29000, México
| | - Julio C. González-Torres
- Área
de Física Atómica Molecular Aplicada (FAMA), CBI, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa
Tamaulipas, Ciudad de México, C.P. 02200, México
| | - A. Rubio-Ponce
- Área
de Física Atómica Molecular Aplicada (FAMA), CBI, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa
Tamaulipas, Ciudad de México, C.P. 02200, México
| | - Oscar Olvera-Neria
- Área
de Física Atómica Molecular Aplicada (FAMA), CBI, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa
Tamaulipas, Ciudad de México, C.P. 02200, México
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9
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Cuong NT, Nguyen HMT, Pham-Ho MP, Nguyen MT. Optical properties of the hydrated charged silver tetramer and silver hexamer encapsulated inside the sodalite cavity of an LTA-type zeolite. Phys Chem Chem Phys 2016; 18:18128-36. [PMID: 27328036 DOI: 10.1039/c6cp02037b] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The optical spectra in the UV-VIS region of the hydrated doubly charged tetramer Ag4(2+) and hydrated multiply charged hexamer Ag6(p+) silver clusters encapsulated inside the sodalite cavity of an LTA-type zeolite have been systematically predicted using DFT, TD-DFT and CASSCF/CASPT2 methods. The optical behaviour of the model hydrated clusters [Ag6(H2O)8(Si24H24O36)](p+) is very sensitive to their charge. Among the cations [Ag6(H2O)8(Si24H24O36)](p+), only the embedded hydrated quadruply charged silver hexamer [Ag6(H2O)8(Si24H24O36)](4+) shows a strong absorption band at ∼420 nm (blue light) and emits light in red color. The absorption spectrum of the hydrated doubly charged silver tetramer cluster [Ag4(H2O)m(Si24H24O36)](2+), which shifts slightly and steadily with the increasing amount of interacting water molecules to longer wavelengths, has a strong peak in the blue region. The water environment forces the silver tetramer to relocate into one side of the cavity instead of at its center as in the case of the non-hydrated [Ag4(Si24H24O36)](2+) cluster. Water molecules act as ligands significantly splitting the energy levels of excited states of the Ag4(2+) and Ag6(4+) clusters. This causes the absorption spectra of the clusters to broaden and the emission to shift to the green-yellow and red part of the visible region.
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Affiliation(s)
- Ngo Tuan Cuong
- Center for Computational Science and Faculty of Chemistry, Hanoi National University of Education, Hanoi, Vietnam.
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10
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Chen L, Zhang J, Freund WM, Kong W. Effect of kinetic energy on the doping efficiency of cesium cations into superfluid helium droplets. J Chem Phys 2015; 143:044310. [PMID: 26233132 PMCID: PMC4522010 DOI: 10.1063/1.4927471] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 07/15/2015] [Indexed: 11/14/2022] Open
Abstract
We present an experimental investigation of the effect of kinetic energy on the ion doping efficiency of superfluid helium droplets using cesium cations from a thermionic emission source. The kinetic energy of Cs(+) is controlled by the bias voltage of a collection grid collinearly arranged with the droplet beam. Efficient doping from ions with kinetic energies from 20 eV up to 480 V has been observed in different sized helium droplets. The relative ion doping efficiency is determined by both the kinetic energy of the ions and the average size of the droplet beam. At a fixed source temperature, the number of doped droplets increases with increasing grid voltage, while the relative ion doping efficiency decreases. This result implies that not all ions are captured upon encountering with a sufficiently large droplet, a deviation from the near unity doping efficiency for closed shell neutral molecules. We propose that this drop in ion doping efficiency with kinetic energy is related to the limited deceleration rate inside a helium droplet. When the source temperature changes from 14 K to 17 K, the relative ion doping efficiency decreases rapidly, perhaps due to the lack of viable sized droplets. The size distribution of the Cs(+)-doped droplet beam can be measured by deflection and by energy filtering. The observed doped droplet size is about 5 × 10(6) helium atoms when the source temperature is between 14 K and 17 K.
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Affiliation(s)
- Lei Chen
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Jie Zhang
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - William M Freund
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
| | - Wei Kong
- Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA
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11
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12
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Cuong NT, Nguyen HMT, Nguyen MT. Theoretical modeling of optical properties of Ag8 and Ag14 silver clusters embedded in an LTA sodalite zeolite cavity. Phys Chem Chem Phys 2013; 15:15404-15. [DOI: 10.1039/c3cp51017d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Bae GT, Aikens CM. TDDFT and CIS Studies of Optical Properties of Dimers of Silver Tetrahedra. J Phys Chem A 2012; 116:8260-9. [DOI: 10.1021/jp305330e] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Gyun-Tack Bae
- Department of Chemistry, Kansas State University, 213 CBC Building, Manhattan,
Kansas 66506, United States
| | - Christine M. Aikens
- Department of Chemistry, Kansas State University, 213 CBC Building, Manhattan,
Kansas 66506, United States
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14
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Cuong NT, Tikhomirov VK, Chibotaru LF, Stesmans A, Rodríguez VD, Nguyen MT, Moshchalkov VV. Experiment and theoretical modeling of the luminescence of silver nanoclusters dispersed in oxyfluoride glass. J Chem Phys 2012; 136:174108. [DOI: 10.1063/1.4707709] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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15
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Abstract
Helium droplets spanning a wide size range, N(He) = 10(3)-10(10), were formed in a continuous-nozzle beam expansion at different nozzle temperatures and a constant stagnation pressure of 20 bars. The average sizes of the droplets have been obtained by attenuation of the droplet beam through collisions with argon and helium gases at room temperature. The results obtained are in good agreement with previous measurements in the size range N(He) = 10(5)-10(7). Moreover, the measurements give the average sizes in the previously uncharacterized range of very large droplets of 10(7)-10(10) atoms. The droplet sizes and beam flux increase rapidly at nozzle temperatures below 6 K, which is ascribed to the formation of droplets within the nozzle interior. The mass spectra of the droplet beam upon electron impact ionization have also been obtained. The spectra show a large increase in the intensity of the He(4) (+) signal upon increase of the droplet size, an effect which can be used as a secondary size standard in the droplet size range N(He) = 10(4)-10(9) atoms.
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Affiliation(s)
- Luis F Gomez
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
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16
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Christen W, Radcliffe P, Przystawik A, Diederich T, Tiggesbäumker J. Argon Solvent Effects on Optical Properties of Silver Metal Clusters. J Phys Chem A 2011; 115:8779-82. [DOI: 10.1021/jp200487s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- W. Christen
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany, and
| | - P. Radcliffe
- Institut für Physik, Universität Rostock, Universitätsplatz 3, 18051 Rostock, Germany
| | - A. Przystawik
- Institut für Physik, Universität Rostock, Universitätsplatz 3, 18051 Rostock, Germany
| | - Th. Diederich
- Institut für Physik, Universität Rostock, Universitätsplatz 3, 18051 Rostock, Germany
| | - J. Tiggesbäumker
- Institut für Physik, Universität Rostock, Universitätsplatz 3, 18051 Rostock, Germany
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17
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Loginov E, Gomez LF, Chiang N, Halder A, Guggemos N, Kresin VV, Vilesov AF. Photoabsorption of Ag(n)(N∼6-6000) nanoclusters formed in helium droplets: transition from compact to multicenter aggregation. PHYSICAL REVIEW LETTERS 2011; 106:233401. [PMID: 21770503 DOI: 10.1103/physrevlett.106.233401] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Indexed: 05/12/2023]
Abstract
Ag(N) clusters with up to thousands of atoms were grown in large He droplets and studied by optical spectroscopy. For N≲10(3) the spectra are dominated by a surface plasmon resonance near 3.8 eV and a broad feature in the UV, consistent with absorption by individual metallic particles. Larger clusters reveal unexpectedly strong broad absorption at low frequencies, extending down to ≈0.5 eV. This suggests a transition from single-center to multicenter formation, in agreement with estimates of cluster growth kinetics in He droplets. Moreover, the spectra of large clusters develop a characteristic dispersion profile at 3.5-4.5 eV, indicative of the coexistence of localized and delocalized electronic excitations in composite clusters, as predicted theoretically.
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Affiliation(s)
- Evgeny Loginov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
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18
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Lecoultre S, Rydlo A, Buttet J, Félix C, Gilb S, Harbich W. Ultraviolet-visible absorption of small silver clusters in neon: Agn(n = 1–9). J Chem Phys 2011; 134:184504. [DOI: 10.1063/1.3589357] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Loginov E, Gomez LF, Vilesov AF. Surface Deposition and Imaging of Large Ag Clusters Formed in He Droplets. J Phys Chem A 2011; 115:7199-204. [DOI: 10.1021/jp200198n] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Evgeny Loginov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Luis F. Gomez
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Andrey F. Vilesov
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
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20
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Callegari C, Ancilotto F. Perturbation Method to Calculate the Interaction Potentials and Electronic Excitation Spectra of Atoms in He Nanodroplets. J Phys Chem A 2011; 115:6789-96. [PMID: 21434657 DOI: 10.1021/jp111157w] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Carlo Callegari
- Institute of Experimental Physics, TU Graz, Petersgasse 16, A-8010 Graz, Austria, EU
| | - Francesco Ancilotto
- Dipartimento di Fisica ‘G. Galilei’, Università di Padova, via Marzolo 8, I-35131 Padova, Italy
- CNR-IOM-Democritos, I-34136 Trieste, Italy
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21
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Pereiro M, Baldomir D, Arias JE. A first-principles study of the influence of helium atoms on the optical response of small silver clusters. J Chem Phys 2011; 134:084307. [PMID: 21361539 DOI: 10.1063/1.3556821] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Optical excitation spectra of Ag(n) and Ag(n)@He(60) (n = 2, 8) clusters are investigated in the framework of the time-dependent density functional theory (TDDFT) within the linear response regime. We have performed the ab initio calculations for two different exact exchange functionals (GGA-exact and LDA-exact). The computed spectra of Ag(n)@He(60) clusters with the GGA-exact functional accounting for exchange-correlation effects are found to be generally in a relatively good agreement with the experiment. A strategy is proposed to obtain the ground-state structures of the Ag(n)@He(60) clusters and in the initial process of the geometry optimization, the He environment is simulated with buckyballs. A redshift of the silver clusters spectra is observed in the He environment with respect to the ones of bare silver clusters. This observation is discussed and explained in terms of a contraction of the Ag-He bonding length and a consequent confinement of the s valence electrons in silver clusters. Likewise, the Mie-Gans predictions combined with our TDDFT calculations also show that the dielectric effect produced by the He matrix is considerably less important in explaining the redshifting observed in the optical spectra of Ag(n)@He(60) clusters.
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Affiliation(s)
- M Pereiro
- Departamento de Física Aplicada, Universidade de Santiago de Compostela, Santiago de Compostela, Spain.
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Alves SG, Vilesov AF, Ferreira SC. Effects of the mean free path and relaxation in a model for the aggregation of particles in superfluid media. J Chem Phys 2009; 130:244506. [DOI: 10.1063/1.3158359] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
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Cargnoni F, Kuś T, Mella M, Bartlett RJ. Ground state potential energy surfaces and bound states of M-He dimers (M=Cu,Ag,Au): a theoretical investigation. J Chem Phys 2008; 129:204307. [PMID: 19045864 DOI: 10.1063/1.3020706] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
We present an ab initio investigation on the ground state interaction potentials [potential energy surface (PES)] between helium and the group 11 metal atoms: copper, silver, and gold. To the best of our knowledge, there are no previous theoretical PESs proposed for Cu-He and Au-He, and a single one for Ag-He [Z. J. Jakubek and M. Takami, Chem. Phys. Lett. 265, 653 (1997)], computed about 10 years ago at MP2 level and significantly improved by our study. To reach a high degree of accuracy in the determination of the three M-He potentials (M=Cu,Ag,Au), we performed extensive series of test computations to establish the appropriate basis set, the theoretical method, and the computational scheme for these systems. For each M-He dimer we computed the PES at the CCSD(T) level of theory, starting from the reference unrestricted Hartree-Fock wave function. We described the inner shells with relativistic small core pseudopotentials, and we adopted high quality basis sets for the valence electrons. We also performed CCSDT computations in a limited set of M-He internuclear distances, adopting a medium-sized basis set, such as to define for each dimer a CCSD(T) to CCSDT correction term and to improve further the quality of the CCSD(T) interaction potentials. The Cu-He complex has minimum interaction energy (E(min)) of -28.4 microhartree at the internuclear distance of 4.59 A (R(min)), and the short-range repulsive wall starts at 4.04 A (R(E=0)). Quite interestingly, the PES of Ag-He is more attractive (E(min)=-33.8 microhartree) but presents nearly the same R(min) and R(E=0) values, 4.60 and 4.04 A, respectively. The interaction potential for Au-He is markedly deeper and shifted at shorter distances as compared to the lighter complexes, with E(min)=-69.6 microhartree, R(min)=4.09 A and R(E=0)=3.60 A. As a first insight in the structure of M-He(n) aggregates, we determined the rovibrational structure of the three M-He dimers. The Cu-He and Ag-He potentials support just few rotational excitations, while the Au-He PES admits also a bound vibrational excitation.
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Mozhayskiy V, Slipchenko MN, Adamchuk VK, Vilesov AF. Use of helium nanodroplets for assembly, transport, and surface deposition of large molecular and atomic clusters. J Chem Phys 2007; 127:094701. [PMID: 17824753 DOI: 10.1063/1.2759927] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The utility of continuous beam of helium droplets for assembly, transport, and surface deposition of metal and molecular clusters is studied. Clusters of propyne having from about 10 to 10(4) molecules were obtained via sequential pickup of molecules by He droplets with average sizes in the range of 10(4)-10(7) atoms. The maximum attainable flux of the propyne molecules carried by He droplets was found to be in the range of (5-15)x10(15) molecules sr(-1) s(-1), being larger in larger droplets. The size of the clusters and the flux of the transported species are ultimately limited by the evaporative extinction of the entire helium droplet upon capture of particles. It is shown that the attenuation of the He droplet beam in the process of the cluster growth can be used in order to obtain the average size and the binding energy of the clusters. Furthermore, we used He droplets for assembling and surface deposition of gold and silver clusters having about 500 atoms. Typical deposition rate of metal atoms of about 3 x 10(15) atoms sr(-1) s(-1) is comparable to or larger than obtained with other beam deposition techniques. We propose that doping of He droplets by Au and Ag atoms in two separate pickup chambers leads to formation of the bimetal clusters having core-shell structure.
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Affiliation(s)
- Vadim Mozhayskiy
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
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Döppner T, Diederich T, Göde S, Przystawik A, Tiggesbäumker J, Meiwes-Broer KH. Ion induced snowballs as a diagnostic tool to investigate the caging of metal clusters in large helium droplets. J Chem Phys 2007; 126:244513. [PMID: 17614570 DOI: 10.1063/1.2745294] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Metal clusters embedded in ultracold helium nanodroplets are exposed to femtosecond laser pulses with intensities of 10(13)-10(14) W/cm2. The influence of the matrix on the ionization and fragmentation dynamics is studied by pump-probe time-of-flight mass spectrometry. Special attention is paid to the generation of helium snowballs around positive metal ions (Me(z+)He(N), z=1,2). Closings of the first and second helium shells are found for silver at N(1)=10,12 and N(2)=32,44, as well as for magnesium at N1=19-20. The distinct abundance enhancement of helium snowballs in the presence of isolated atoms and small clusters in the droplets is used as a diagnostics to explore the cage effect. For silver, a reaggregation of the clusters is observed at 30 ps after femtosecond laser excitation.
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Affiliation(s)
- Tilo Döppner
- Institut für Physik, Universität Rostock, Universitätsplatz 3, 18051 Rostock, Germany
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Stiles PL, Miller RE. High-Resolution Infrared Spectroscopy of HCN−Agn (n = 1−4) Complexes Solvated in Superfluid Helium Droplets. J Phys Chem A 2007; 111:7382-90. [PMID: 17518451 DOI: 10.1021/jp0707945] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
High-resolution infrared spectroscopy has been used to determine the structures, C-H stretching frequencies, and dipole moments of the HCN-Agn (n = 1-3) complexes formed in superfluid helium droplets. The HCN-Ag4 cluster was tentatively assigned based upon pick-up cell pressure dependencies and harmonic vibrational shift calculations. Ab initio and density functional theory calculations were used in conjunction with the high-resolution spectra to analyze the bonding nature of each cluster. All monoligated species reported here are bound through the nitrogen end of the HCN molecule. The HCN-Agn complexes are structurally similar to the previously reported HCN-Cun clusters, with the exception of the HCN-Ag binary complex. Although the interaction between the HCN and the Agn clusters follows the same trends as the HCN-Cun clusters, the more diffuse nature of the electrons surrounding the silver atoms results in a much weaker interaction.
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Affiliation(s)
- Paul L Stiles
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Przystawik A, Radcliffe P, Diederich T, Döppner T, Tiggesbäumker J, Meiwes-Broer KH. Photoelectron studies of neutral Ag3 in helium droplets. J Chem Phys 2007; 126:184306. [PMID: 17508802 DOI: 10.1063/1.2723087] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Photoelectron spectra of neutral silver trimers, grown in ultracold helium nanodroplets, are recorded after ionization with laser pulses via a strong optical resonance of this species. Varying the photon energy reveals that direct vertical two-photon ionization is hindered by a rapid relaxation into the lower edge of a long-living excited state manifold. An analysis of the ionization threshold of the embedded trimer yields an ionization potential of 5.74+/-0.09 eV consistent with the value found in the gas phase. The asymmetrical form of the electron energy spectrum, which is broadened toward lower kinetic energies, is attributed to the influence of the matrix on the photoionization process. The lifetime of the excited state was measured in a two-color pump-probe experiment to be 5.7+/-0.6 ns.
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Tiggesbäumker J, Stienkemeier F. Formation and properties of metal clusters isolated in helium droplets. Phys Chem Chem Phys 2007; 9:4748-70. [PMID: 17712454 DOI: 10.1039/b703575f] [Citation(s) in RCA: 163] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The unique conditions forming atomic and molecular complexes and clusters using superfluid helium nanodroplets have opened up an innovative route for studying the physical and chemical properties of matter on the nanoscale. This review summarizes the specific characteristics of the formation of atomic clusters partly generated far from equilibrium in the helium environment. Special emphasis is on the optical response, electronic properties as well as dynamical processes which are mostly affected by the surrounding quantum matrix. Experiments include the optical induced response of isolated cluster systems in helium under quite different excitation conditions ranging from the linear regime up to the violent interaction with a strong laser field leading to Coulomb explosion and the generation of highly charged atomic fragments. The variety of results on the outstanding properties in the quantum size regime highlights the peculiar capabilities of helium nanodroplet isolation spectroscopy.
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Döppner T, Diederich T, Przystawik A, Truong NX, Fennel T, Tiggesbäumker J, Meiwes-Broer KH. Charging of metal clusters in helium droplets exposed to intense femtosecond laser pulses. Phys Chem Chem Phys 2007; 9:4639-52. [PMID: 17700865 DOI: 10.1039/b703707d] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We review the strong field (10(13)-10(16) W cm(-2)) laser excitation of metal clusters (Cd(N), Ag(N) and Pb(N)) embedded in He nanodroplets. Plasmon enhanced ionization obtained by stretching the laser pulses to several hundreds of femtoseconds or by using dual pulses with a suitable optical delay leads to a Coulomb explosion of highly charged atomic ions. The charging dynamics can be well described by corresponding semiclassical Vlasov simulations. The influence of the He environment on the ionization process and on the final charge distribution is discussed. Evidence is found that He(2+) is generated in collisions with highly charged metal ions. In contrast, singly and doubly charged ions with low recoil energies induce the formation of He snowballs with a distinct shell structure around the ion. Laser intensity thresholds for snowball formation and for the ionization of clusters are investigated by applying intensity selective scanning.
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Affiliation(s)
- T Döppner
- Institut für Physik, Universität Rostock, Universitätsplatz 3, 18051, Rostock, Germany.
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Zhao GF, Zeng Z. Geometrical and electronic structures of AumAgn (2⩽m+n⩽8). J Chem Phys 2006; 125:014303. [PMID: 16863294 DOI: 10.1063/1.2210470] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The structural and electronic properties of Au(m)Ag(n) binary clusters (2 < or = m + n < or = 8) have been investigated by density functional theory with relativistic effective core potentials. The results indicate that Au atoms tend to occupy the surface of Au(m)Ag(n) clusters (n > or = 2 and m > or = 2). As a result, segregation of small or big bimetallic clusters can be explained according to the atomic mass. The binding energies of the most stable Au(m)Ag(n) clusters increase with increasing m+n. The vertical ionization potentials of the most stable Au(m)Ag(n) clusters show odd-even oscillations with changing m+n. The possible dissociation channels of the clusters considered are also discussed.
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Affiliation(s)
- G F Zhao
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
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Fielicke A, Rabin I, Meijer G. Far-Infrared Spectroscopy of Small Neutral Silver Clusters. J Phys Chem A 2006; 110:8060-3. [PMID: 16805491 DOI: 10.1021/jp062095i] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The vibrational spectra of Ag(3) and Ag(4) are recorded in the far-infrared between 100 and 220 cm(-1) using multiple photon dissociation spectroscopy of their complexes with Ar atoms. For Ag(3)-Ar two IR active bands are found at 113 and 183 cm(-1), for Ag(4)-Ar one band at 163 cm(-1) and very weak IR activity at 193 cm(-1) are observed. This, together with recent theoretical studies, allows for a reassignment of the controversial vibrational data reported earlier for the bare Ag(3) cluster. The influence of the number of Ar atoms in the complexes on the frequency of the IR active modes is found to be minor. However, the low-frequency IR-active band of Ag(3) shifts with increasing Ar coverage from 113 cm(-1) for Ag(3)-Ar to about 120 cm(-1) for Ag(3)-Ar(4), the value known for Ag(3) embedded in rare gas matrices.
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Affiliation(s)
- André Fielicke
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.
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Radcliffe P, Przystawik A, Diederich T, Döppner T, Tiggesbäumker J, Meiwes-Broer KH. Excited-state relaxation of Ag8 clusters embedded in helium droplets. PHYSICAL REVIEW LETTERS 2004; 92:173403. [PMID: 15169149 DOI: 10.1103/physrevlett.92.173403] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2003] [Indexed: 05/24/2023]
Abstract
Neutral silver clusters Ag(N) are grown in ultracold helium nanodroplets. By exploiting a strong absorption resonance recently found for Ag8, first photoelectron spectra of this neutral species are recorded. Variation of the laser photon energy reveals that direct vertical two-photon ionization is hindered by rapid relaxation into the lower edge of a long-living excited state manifold. The analysis of the dynamics gives a precise value of (6.89+/-0.09) eV for the vertical ionization potential of Ag8. The influence of the helium matrix on photoemission is discussed.
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Affiliation(s)
- Paul Radcliffe
- Fachbereich Physik, Universität Rostock, 18051 Rostock, Germany
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Schweizer A, Weber JM, Gilb S, Schneider H, Schooss D, Kappes MM. Electronic photodissociation spectroscopy of Au4+⋅Arn, n=0–4: Experiment and theory. J Chem Phys 2003. [DOI: 10.1063/1.1590752] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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