The optical absorption spectra of small Silver clusters (n=8–39) embedded in rare gas matrices

Harbich, W.; Fedrigo, S.; Buttet, J.

doi:10.1007/bf01429124

Cited by 86 publications

(81 citation statements)

References 7 publications

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“…This is the first unambiguous assignment of a fluorescence for a metallic cluster larger than n 4. Our results are compared to optical absorption [11] and recent two-photon ionization experiments in helium droplets [18].…”

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confidence: 94%

“…Wöste and co-workers have shown that, in the case of K 3 , the fragmentation of optically excited clusters occurs within a few hundred femtoseconds [10]. This is much shorter than the characteristic time scale necessary for a dipole transition and therefore no fluorescence can be observed in this case.Alternatively, optical absorption measurements of matrix isolated and mass-selected silver clusters have been performed for sizes up to n 39 [11]. No signal decrease has been observed over time, so it is clear that the matrix is effectively preventing the clusters from dissociating.…”

mentioning

confidence: 99%

“…Alternatively, optical absorption measurements of matrix isolated and mass-selected silver clusters have been performed for sizes up to n 39 [11]. No signal decrease has been observed over time, so it is clear that the matrix is effectively preventing the clusters from dissociating.…”

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confidence: 99%

“…Ag 7 1 Ag 1 [11]. The comparison between the absorption spectrum of Ag 8 and its excitation and fluorescence spectra (see Fig.…”

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confidence: 99%

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Ag8Fluorescence in Argon

et al. 2001

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The fluorescence of Ag 8 in an argon matrix and in argon droplets is reported. This is the first unambiguous assignment of the fluorescence of a metal cluster larger than the tetramer, indicating that the excited state lifetime is longer than previously thought. It is discussed as a possible result of a matrix cage effect. The excitation spectrum is compared with two-photon-ionization measurements of Ag 8 in helium droplets and to known absorption data. The agreement is excellent. We propose that the excited states relax rapidly through vibrational coupling to a long-lived state, from which the fluorescence occurs. DOI: 10.1103/PhysRevLett.86.2992 Optical spectroscopy has proven to be a powerful tool for understanding the electronic structure of atoms and molecules. Over the past decade these techniques have also been applied very successfully to metal clusters. Small metal clusters have been investigated in free beam experiments, using techniques such as resonant two-photon-ionization (R2PI) spectroscopy [1,2], laser-induced fluorescence [3], and pump-probe [4,5] techniques. Fragmentation becomes, however, more important as the cluster size increases and nondissociative electronic excitation processes have not been observed for free metal clusters larger than trimers [6]. Photodepletion spectroscopy was therefore used to measure optical absorption spectra of free metal clusters larger than three atoms [7][8][9].Also the fluorescence lines of free metal clusters are expected to be observed only for very small clusters. Wöste and co-workers have shown that, in the case of K 3 , the fragmentation of optically excited clusters occurs within a few hundred femtoseconds [10]. This is much shorter than the characteristic time scale necessary for a dipole transition and therefore no fluorescence can be observed in this case.Alternatively, optical absorption measurements of matrix isolated and mass-selected silver clusters have been performed for sizes up to n 39 [11]. No signal decrease has been observed over time, so it is clear that the matrix is effectively preventing the clusters from dissociating. This so-called cage effect is well known for molecules in a gas atmosphere or in a liquid. In the case of I 2 , for example, it has been shown that a single rare gas atom adsorbed on the molecule hinders the photofragmentation and allows the fluorescence [12].This opens the possibility of observing fluorescence for small metallic clusters if the excited state of the particle has a sufficient lifetime for a radiative transition to take place. However, with increasing size the competition between the different possible relaxation processes (vibrations, fluorescence, fragmentation) increases and, due to their shorter characteristic time, the radiationless relaxation processes are expected to quench the fluorescence [13][14][15].In the case of silver, fluorescence of Ag 3 and, more recently, Ag 4 has been unequivocally determined. A number of hitherto unidentified emission bands have been observed in the studies of non-mass-s...

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confidence: 94%

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confidence: 99%

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confidence: 99%

“…Ag 7 1 Ag 1 [11]. The comparison between the absorption spectrum of Ag 8 and its excitation and fluorescence spectra (see Fig.…”

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confidence: 99%

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Ag8Fluorescence in Argon

et al. 2001

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“…From the technological viewpoint, clusters can be regarded as the precursors to a new generation of nanostructured materials and devices [3]. From a fundamental perspective, deposition allows the whole range of surface physics techniques to be deployed to explore the properties of relatively numerous confined quantum systems [4]. The dynamics of the cluster-surface interaction is itself the subject of increasing attention [5][6][7].…”

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Energetic Impact of Size-Selected Metal Cluster Ions on Graphite

et al. 1998

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We have investigated the impact of size-selected metal cluster ions ͑Ag n 2 ͒ on a covalently bonded substrate (graphite) over the energy range 15 -1500 eV by a combination of scanning tunneling microscopy and molecular dynamics simulations. The key result is that the fate of the cluster (penetration into the surface versus diffusion and aggregation on the surface), at intermediate energies, depends on the lateral localization of the cluster kinetic energy at specific surface sites and thus, for small clusters, on the orientation of the cluster and the target substrate site. [S0031-9007(98)07519-X]

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