Relative Stability of Small Silver, Platinum, and Palladium Doped Gold Cluster Cations

Piero Ferrari,Ewald Janssens

doi:10.3390/app9081666

Abstract

The stability patterns of single silver, platinum, and palladium atom doped gold cluster cations, MAuN−1+ (M = Ag, Pt, Pd; N = 3–6), are investigated by a combination of photofragmentation experiments and density functional theory calculations. The mass spectra of the photofragmented clusters reveal an odd-even pattern in the abundances of AgAuN−1+, with local maxima for clusters containing an even number of valence electrons, similarly to pure AuN+. The odd-even pattern, however, disappears upon Pt and Pd doping. Computed dissociation energies agree well with the experimental findings for the different doped clusters. The effect of Ag, Pt, and Pd doping is discussed on the basis of an analysis of the density of states of the N = 3–5 clusters. Whereas Ag delocalizes its 5s valence electron in all sizes, this process is size-specific for Pt and Pd.

Highlights

Small metal clusters in the gas phase, produced under conditions where cluster-cluster and cluster-environment interactions are absent, are ideal model systems for a fundamental understanding of the different physical and chemical properties of matter
Since here we focus on doped species, the favored channel may be size dependent
In many DFT studies, it is predicted that the 2D to 3D transition takes place at N = 8, the planar and 3D isomers of Au8 + are close in energy [35,55]. The source for this discrepancy can be related to the lack of implicit relativistic effects in most DFT studies on gold clusters, that question goes beyond the scope of this study

Summary

Introduction

Small metal clusters in the gas phase, produced under conditions where cluster-cluster and cluster-environment interactions are absent, are ideal model systems for a fundamental understanding of the different physical and chemical properties of matter. In a gas phase experiment, clusters are produced and characterized as a function of size, composition, and charge state with atomic precision, and their inherent small size allows for direct comparison with detailed quantum chemical calculations. Many examples in the literature can be found in which small clusters are used to elucidate intrinsic properties of matter, such as the stability of alloy complexes [1,2], the reactivity and catalytic properties of metals [3,4], the optical responses of matter [5,6], and the magnetic coupling of different elements and their evolution from the atom to the bulk [7,8]. Small gold clusters possess unique optical properties [6,14]

Methods

Results

Discussion

Conclusion