Structural and Electronic Properties of AuSin- (n=4-12) Clusters: Photoelectron Spectroscopy and Ab Initio Calculations

AuSin- (n = 4-12) clusters were produced with a laser vaporization source and investigated by photoelectron spectroscopy. The swarm-intelligence-based CALYPSO structure search method and ab initio calculations were employed to determine their ground-state structures. The results revealed that the most stable isomers of AuSin- (n = 4-12) cluster anions are all exohedral structures, in which the Au atom caps the vertex, edge, or surface of the bare Si clusters. The endohedral and exohedral structures of neutral AuSi11 are nearly degenerate in energy. The most stable structure of neutral AuSi12 is endohedral. The growth mechanism of AuSin- cluster anions is compared with those of AuGen-, AgSin-, and CuSin- clusters. It implies that the bond strengths of Au-Si and Au-Ge play important roles in the formation of cage structures for AuSi12- and AuGen-, while the different atomic radii of coinage metals, different bond strengths, and the strong relativistic effect in Au atom are responsible for the different growth mechanisms of Si clusters doped with different coinage metals.