| Résumé | The electronic and geometric properties of gas-phase exohedral C60Na<sub>N</sub><sup>-</sup>, C70Na<sub>N</sub><sup>-</sup>, and C60Au<sub>N</sub><sup>-</sup> cluster anions are investigated. Time-of-flight mass spectrometry and photoelectron spectroscopy (PES) reveal complex-specific arrangements of the sodium and the gold atoms on the fullerene cage. The electron affinity of C60AuN clearly shows even�odd alternation with the number of Au atoms, which suggests a "dry" structure where Au atoms aggregate as a cluster on the C60. In contrast, C60NaN and C70NaN show a "wet" structure having the Na atoms packed into stable trimers on the surface. For C60NaN (N = 0 to 4), PES experiments at a high photodetachment energy (5.81 eV) allow us to deduce the net charge transferred from the sodium atoms to the lowest unoccupied molecular orbital of the fullerene. For larger C60NaN, moreover, a metallic transition is shown to occur at N~13, and analysis of the adiabatic electron affinity variations allows the identification of the first magic sizes corresponding to electronic shell closure in the sodium layer. |
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