Electronic and geometric structure of doped rare-gas clusters: surface, site and size effects studied with luminescence spectroscopy

  • R. von Pietrowski
  • K. von Haeften
  • T. Laarmann
  • T. Möller
  • L. Museur
  • A. V. Kanaev
Clusters and Nanostructures

DOI: 10.1140/epjd/e2006-00033-3

Cite this article as:
von Pietrowski, R., von Haeften, K., Laarmann, T. et al. Eur. Phys. J. D (2006) 38: 323. doi:10.1140/epjd/e2006-00033-3

Abstract.

The electronic and geometric structure of rare gas clusters doped with rare-gas atoms Rg = Xe, Kr or Ar is investigated with fluorescence excitation spectroscopy in the VUV spectral range. Several absorption bands are observed in the region of the first electronic excitations of the impurity atoms, which are related to the lowest spin-orbit split atomic 3P1 and 1P1 states. Due to influence of surrounding atoms of the cluster, the atomic lines are shifted to the blue and broadened (“electronical cage effect”). From the known interaction potentials and the measured spectral shifts the coordination of the impurity atom in ArN, KrN, NeN and HeN could be studied in great detail. In the interior of KrN and ArN the Xe atoms are located in substitutional sites with 12 nearest neighbours and internuclear distances comparable to that of the host matrix. In NeN and HeN the cluster atoms (18 and 22, respectively) arrange themselves around the Xe impurity with a bondlength comparable to that of the heteronuclear dimer. The results confirm that He clusters are liquid while Ne clusters are solid for N≥ 300. Smaller Ne clusters exhibit a liquid like behaviour. When doping is strong, small Rgm-clusters (Rg = Xe, Kr, Ar, m≤10 2) are formed in the interior sites of the host cluster made of Ne or He. Specific electronically excited states, assigned to interface excitons are observed. Their absorption bands appear and shift towards lower energy when the cluster size m increases, according to the Frenkel exciton model. The characteristic bulk excitons appear in the spectra, only when the cluster radius exceeds the penetration depth of the interface exciton, which can be considerably larger than that in free Rgm clusters. This effect is sensitive to electron affinities of the guest and the host cluster.

PACS.

36.40.-c Atomic and molecular clusters 36.40.Mr Spectroscopy and geometrical structure of clusters 73.20.-r Electron states at surfaces and interfaces 

Copyright information

© EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2006

Authors and Affiliations

  • R. von Pietrowski
    • 1
  • K. von Haeften
    • 2
  • T. Laarmann
    • 3
  • T. Möller
    • 4
  • L. Museur
    • 5
  • A. V. Kanaev
    • 6
  1. 1.Hamburger Synchrotronstrahlungslabor HASYLAB at Deutsches Elektronen Synchrotron DESYHamburgGermany
  2. 2.Lehrstuhl für Physikalische Chemie II, Gebäude NC, Raum 7/33, Ruhr-Universität Bochum, Universitätsstr. 150BochumGermany
  3. 3.Max-Born InstituteBerlinGermany
  4. 4.Institut für Atomare Physik, Technische Universität BerlinBerlinGermany
  5. 5.Laboratoire de Physique des Lasers LPL, CNRS, Institut Galilée, Université Paris-13VilletaneuseFrance
  6. 6.Laboratoire d'Ingénierie des Matériaux et des Hautes Pressions LIMHP, CNRS, Institut Galilée, Université Paris-13VilletaneuseFrance

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