RESUMO
Large-sized gold Aun- anion clusters exhibit structural characteristics drastically different from other coinage metals. Typically, coinage metal nanoclusters exhibit a 13-atom icosahedral core at the cluster size of 55. Gold clusters, contrarily, do not entail this core until the size reaches 60. Here, we investigated the robustness of the icosahedral core within the large-sized Aun- anion clusters. We found that the icosahedral core persists over the size of range of n = 61-66. To adapt the exceptional robustness of the icosahedral core, the shells of the clusters tend to undergo notable structural deformations with polygonal defects. As the cluster size increases from 61 to 66, the core starts to become distorted at n = 64 and the space between the core and shell becomes enlarged. To our knowledge, this is the first theoretical study that provides the simulated photoelectron spectra of the two largest sized gold clusters: Au65- and Au66-.
RESUMO
We report the first joint anion photoelectron spectroscopy and theoretical study on how O2-binding affects the structures of medium even-sized gold clusters, Aun- (n = 20-34), a special size region that entails a variety of distinct structures. Under the temperature conditions in the current photoelectron spectroscopy experiment, O2-bound gold clusters were observed only for n = 22-24 and 34. Nevertheless, O2 binding with the clusters in the size range of n = 20-34 can be still predicted based on the obtained global-minimum structures. Consequently, a series of structural transitions, from the pyramidal to fused-planar to core-shell structures, are either identified or predicted for the AunO2- clusters, where the O2-binding is in either superoxo or peroxo fashion. The identified global-minimum structures of AunO2- (n = 20-34) also allow us to gain improved understanding of why the clusters Aun- (n = 26-32) are less reactive with O2 in comparison to others.
