Photodissociation and photoionization of sodium coated C60 clusters

• Published in: The European physical journal. D, Atomic, molecular, and optical physics Vol. 25; no. 1; pp. 31 - 40
• Main Authors: Pellarin, M., Cottancin, E., Lermé, J., Vialle, J.L., Broyer, M., Tournus, F., Masenelli, B., Mélinon, P.
• Format: Journal Article
• Language: English
• Published: EDP Sciences 01-07-2003
• ISSN: 1434-6060; 1434-6079
• DOI: 10.1140/epjd/e2003-00216-4

(C60)mNan clusters are produced in a tandem laser vaporization source and analyzed by photoionization and photofragmentation time-of-flight mass spectroscopy. At low sodium coverage, the special behavior of (C60)m=1,2Nan clusters is consistent with a significant electron transfer from the first six adsorbed atoms towards each of the C60 fullerenes and an ionic-like bonding in this size range. However, the stability of the (C60)Na3+ cation is found much more pronounced than the one of (C60)Na7+ predicted to be a magic size under the hypothesis of a full charge transfer from the metal atoms to the C60 molecule. When more sodium atoms are present, metal-metal bonds tend to become preponderant and control the cluster properties. Relative to the number of sodium atoms, an odd-even alternation in their stability is explained by the high dissociation rates for even-numbered clusters. The even clusters evaporate neutral sodium atoms whereas odd ones prefer to evaporate Na2 molecules. The hypotheses for the growth of a sodium droplet that does not wet the fullerene surface or for the formation of a concentric metallic layer are discussed in the light of this study.