Probing the Structural Evolution of Medium-Sized Gold Clusters: Au_n⁻ (n = 27−35)

Abstract

The structural evolution of negatively charged gold clusters (Au(n)(-)) in the medium size range for n = 27-35 has been investigated using photoelectron spectroscopy (PES) and theoretical calculations. New PES data are obtained using Ar-seeded He supersonic beams to achieve better cluster cooling, resulting in well-resolved spectra and revealing the presence of low-lying isomers in a number of systems. Density-functional theory calculations are used for global minimum searches. For each cluster anion, more than 200 low-lying isomers are generated using the basin-hopping global minimum search algorithm. The most viable structures and low-lying isomers are obtained using both the relative energies and comparisons between the simulated spectra and experimental PES data. The global minimum structures of Au(n)(-) (n = 27, 28, 30, and 32-35) are found to exhibit low-symmetry core-shell structures with the number of core atoms increasing with cluster size: Au(27)(-), Au(28)(-), and Au(30)(-) possess a one-atom core; Au(32)(-) features a three-atom triangular core; and Au(33)(-) to Au(35)(-) all contain a four-atom tetrahedral core. The global searches reveal that the tetrahedral core is a popular motif for low-lying structures of Au(33)(-) to Au(35)(-). The structural information forms the basis for future chemisorption studies to unravel the catalytic effects of gold nanoparticles.

Formation and Stability of Low‐Dimensional Structures for Group VIIIB and IB Transition Metals: The Role of sd4 Hybridization

“…We are aware that many theoretical and experimental studies have already been conducted for Au nanoclusters and concluded that Au nanoclusters undergo evolution with respect to size: the most stable structure of Au n clusters is planar for n < 14,22 cage for 16 ≦ n ≦ 20,11, 16 and filled structures for n > 20 21. In the present work, we placed our attention on the 1D Au nanostructures.…”

Investigating the structural evolution of thiolate protected gold clusters from first-principles

“…[2][3][4][5][6][7][8][9][10] Moreover, comparison with experimental data such as a photoelectron spectrum of anionic clusters is a key step to determine the structures of the most stable clusters. For medium-sized thiolate-protected gold clusters, the generation of low-lying structures from DFT calculations is computationally very expensive.…”

“…87 Gao et al provided an alternative view of the multi-layer structure of Au 102 (p-MBA) 44 . From their structural analysis, the embedded Au 102 cluster was decomposed into a multi-layered structure described as Au 54 (penta-star)@Au 38 (ten wings) @Au 10 (two pentagon caps) as shown in Fig. 2.…”

“…For gas-phase gold clusters (Au N q , q ¼ 0, AE1, N # 60), significant advances have been made through combined experimental and theoretical efforts over the past two decades, which provide deeper insights into their size-dependent atomic structures, and thereby the critical information needed for understanding the structure-size-property relationship. [1][2][3][4][5][6][7][8][9][10] The combination of global optimization algorithms and density functional theory 11,12 (DFT) calculation has been proven to be a powerful tool to generate structures of low-energy gold clusters, as well as for the determination of the lowest-energy structure by comparing computed photoelectron spectra with the experimental spectra. For example, unique structural transitions for gold cluster anions in the size range of N ¼ 14-20 have been revealed, e.g., from the flat cage to hollow cage and to tetrahedral pyramid.…”

Au40: A large tetrahedral magic cluster

“…What is unique about the two structures is that they both have a sizable HOMO-LUMO gap, indicating their The two Au 38 minima are also interesting in that they have two adatoms on the Au 4 @Au 32 core shell. This construction shares some similarity with the Au 35 structure where one adatom is on the Au 4 @Au 30 core shell 21 . What Au 38 's structure suggested to us is that Au 40 's structure can build upon the Au 4 @Au 32 core-shell framework but with four adatoms placed in tetrahedral symmetry.…”