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Electronic structure transformation in small bare Au clusters as seen by x-ray photoelectron spectroscopy

Andersson, T.; Zhang, C.; Björneholm, O. LU ; Mikkelä, M. H. LU ; Jänkälä, K.; Anin, D.; Urpelainen, S. LU ; Huttula, M. and Tchaplyguine, M. LU (2017) In Journal of Physics B: Atomic, Molecular and Optical Physics 50(1).
Abstract

Free bare gold clusters in the size range from few tens to few hundred atoms (≤1 nm dimensions) have been produced in a beam, and the size-dependent development of their full valence band including the 5d and 6s parts has been mapped 'on the fly' by synchrotron-based photoelectron spectroscopy. The Au 4f core level has been also probed, and the cluster-specific Au 4f ionization energies have been used to estimate the cluster size. The recorded in the present work valence spectra of the small clusters are compared with the spectra of the large clusters ( N ∼ 103) created by us using a magnetron-based gas aggregation source. The comparison shows a substantially narrower 5d valence band and the decrease in its splitting for gold... (More)

Free bare gold clusters in the size range from few tens to few hundred atoms (≤1 nm dimensions) have been produced in a beam, and the size-dependent development of their full valence band including the 5d and 6s parts has been mapped 'on the fly' by synchrotron-based photoelectron spectroscopy. The Au 4f core level has been also probed, and the cluster-specific Au 4f ionization energies have been used to estimate the cluster size. The recorded in the present work valence spectra of the small clusters are compared with the spectra of the large clusters ( N ∼ 103) created by us using a magnetron-based gas aggregation source. The comparison shows a substantially narrower 5d valence band and the decrease in its splitting for gold clusters in the size range of few hundred atoms and below. Our DFT calculations involving the pseudopotential method show that the 5d band width of the ground state increases with the cluster size and by the size N = 20 becomes comparable with the experimental width of the valence photoelectron spectrum. Similar to the earlier observations on supported clusters we interpret our experimental and theoretical results as due to the undercoordination of a large fraction of atoms in the clusters with N ∼ 102 and below. The consequences of such electronic structure of small gold clusters are discussed in connection with their specific physical and chemical properties related to nanoplasmonics and nanocatalysis.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Au 4f core level, Au 5d valence band, free bare clusters, size-dependent electronic structure, synchrotron radiation, x-ray photoelectron spectroscopy
in
Journal of Physics B: Atomic, Molecular and Optical Physics
volume
50
issue
1
publisher
IOP Publishing
external identifiers
  • scopus:85009062764
  • wos:000391492400001
ISSN
0953-4075
DOI
10.1088/1361-6455/50/1/015102
language
English
LU publication?
yes
id
2134d46b-b677-46b2-926e-78fc80119b06
date added to LUP
2017-02-28 12:00:10
date last changed
2018-02-18 04:57:37
@article{2134d46b-b677-46b2-926e-78fc80119b06,
  abstract     = {<p>Free bare gold clusters in the size range from few tens to few hundred atoms (≤1 nm dimensions) have been produced in a beam, and the size-dependent development of their full valence band including the 5d and 6s parts has been mapped 'on the fly' by synchrotron-based photoelectron spectroscopy. The Au 4f core level has been also probed, and the cluster-specific Au 4f ionization energies have been used to estimate the cluster size. The recorded in the present work valence spectra of the small clusters are compared with the spectra of the large clusters ( N ∼ 10<sup>3</sup>) created by us using a magnetron-based gas aggregation source. The comparison shows a substantially narrower 5d valence band and the decrease in its splitting for gold clusters in the size range of few hundred atoms and below. Our DFT calculations involving the pseudopotential method show that the 5d band width of the ground state increases with the cluster size and by the size N = 20 becomes comparable with the experimental width of the valence photoelectron spectrum. Similar to the earlier observations on supported clusters we interpret our experimental and theoretical results as due to the undercoordination of a large fraction of atoms in the clusters with N ∼ 10<sup>2</sup> and below. The consequences of such electronic structure of small gold clusters are discussed in connection with their specific physical and chemical properties related to nanoplasmonics and nanocatalysis.</p>},
  articleno    = {015102},
  author       = {Andersson, T. and Zhang, C. and Björneholm, O. and Mikkelä, M. H. and Jänkälä, K. and Anin, D. and Urpelainen, S. and Huttula, M. and Tchaplyguine, M.},
  issn         = {0953-4075},
  keyword      = {Au 4f core level,Au 5d valence band,free bare clusters,size-dependent electronic structure,synchrotron radiation,x-ray photoelectron spectroscopy},
  language     = {eng},
  month        = {01},
  number       = {1},
  publisher    = {IOP Publishing},
  series       = {Journal of Physics B: Atomic, Molecular and Optical Physics},
  title        = {Electronic structure transformation in small bare Au clusters as seen by x-ray photoelectron spectroscopy},
  url          = {http://dx.doi.org/10.1088/1361-6455/50/1/015102},
  volume       = {50},
  year         = {2017},
}