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报告人： Dr. Piero Ferrari（比利时鲁汶大学） 邀请人：李新奇 Email: xinqi.li@tju.edu.cn Abstract: Ever since the discoveryof “magic” sizes in mass spectra of gas-phase sodium clusters, the search forclusters with enhanced stability has been an important item in the study ofmetallic clusters. Not only is high thermodynamic stability an important conditionfor possible applications using size-selected clusters, understanding of thecompetition between localization and delocalization of valence electrons inmetallic clusters also is of fundamental interest. Nowadays, it is well knownthat those “magic” clusters have closed electronic shells of delocalizedvalence electrons, but the interplay between electronic shell structure andcluster geometry as well as the modification of this shell structure by dopantatoms in bimetallic clusters is not fully understood. In this presentation, acombination of mass spectrometry experiments with density functional theorycalculations will be discussed, in the investigation of the size dependentstability of palladium doped gold clusters. Pd doping affects both the electronicstructure and the geometry of atomic gold clusters. The stability of theclusters is studied experimentally by photofragmentation and decay channelanalysis and computationally by density functional theory. The correspondencebetween experiments and computations is excellent. Depending on cluster sizethe Pd dopant delocalizes one valence electron, explaining the enhancedstability to the PdAu6+ cluster, or remains with all 4d electrons localized,which is the case for the particularly stable PdAu9+ cluster. In the formercase six electrons are delocalized, closing an electronic shell in atwo-dimensional system, whereas in the latter case there are eight delocalizedelectrons, corresponding to a three-dimensional shell closure. |
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