PNNL

Abstract

Among the large Aun – clusters for n > 20, the photoelectron spectra of Au34 – exhibit the largest energy gap (0.94 eV) with well-resolved spectral features, making it a good candidate for structural consideration in conjunction with theoretical studies. Extensive structural searches at several levels of theory revealed that the low-lying isomers of Au34 – can be characterized as fluxional core-shell type structures with 4 or 3 inner atoms and 30 or 31 outer atoms, i.e., Au4@Au30 – and Au3@Au31 –, respectively. Detailed comparisons between theoretical and photoelectron results suggest that the most probable ground state structures of Au34 – are of the Au4@Au30 – type. The 30 outer atoms seem to be disordered or fluxional, giving rise to a number of low-lying isomers with very close energies and simulated photoelectron spectra. The fluxional nature of the outer layer in large gold clusters or nanoparticles may have important implications for their remarkable catalytic activities.