Structure evolution of gold cluster anions between the planar and cage structures by isoelectronic substitution: Au(n)- (n = 13-15) and MAu(n)- (n = 12-14; M = Ag, Cu)

The structural and electronic effects of isoelectronic substitution by Ag and Cu atoms on gold cluster anions in the size range between 13 and 15 atoms are studied using a combination of photoelectron spectroscopy and first-principles density functional calculations. The most stable structures of the doped clusters are compared with those of the undoped Au clusters in the same size range. The joint experimental and theoretical study reveals a new C(3v) symmetric isomer for Au(13)(-), which is present in the experiment, but has hitherto not been recognized. The global minima of Au(14)(-) and Au(15)(-) are resolved on the basis of comparison between experiment and newly computed photoelectron spectra that include spin-orbit effects. The coexistence of two isomers for Au(15)(-) is firmly established with convincing experimental evidence and theoretical calculations. The overall effect of the isoelectronic substitution is minor on the structures relative to those of the undoped clusters, except that the dopant atoms tend to lower the symmetries of the doped clusters.