Photon Emission Spectroscopy of Single Oxide-Supported Ag-Au Alloy Clusters

Abstract

The alloying of Ag and Au has been investigated on the level of individual clusters by analyzing the light emission excited by electron injection from an STM tip. Different Ag-Au alloy and shell-core clusters have been prepared at room temperature on a thin Al 2 O 3 film on NiAl͑110͒ by simultaneous and successive deposition of both noble metals. For simultaneous deposition, one Mie-plasmon resonance has been detected with a wavelength position shifting from the pure Au to the Ag value with increasing Ag content. The results are in agreement with calculations based on Mie theory indicating a complete mixing of both materials. For successive deposition, two Mie resonances have been observed, attributed to plasmon excitations in the shell and core of the clusters. Comparing these results to model calculations, a considerable intermixing of the core and shell materials is concluded, which is especially strong in Au shell-Ag core clusters.

Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

“…Further experiments have been performed for Ag and Ag-Au alloy particles on alumina thin films, putting special emphasis on the interrelation between the plasmon-mediated emission behavior and the geometry and chemical composition of the individual particles. 119,137 For Ag clusters, for example, a blue-shift of the plasmon resonance was revealed with decreasing particle diameter, 119 reflecting the diminishing influence of the Ag d-electrons on the plasmon energy in aggregates with large surface-to-volume ratio. STM-induced light emission has also been observed for individual Zn-Etiol molecules deposited on alumina/NiAl(110), as shown in .2.13.…”

Real-Time Ab Initio KMC Simulation of the Self-Assembly and Sintering of Bimetallic Epitaxial Nanoclusters: Au + Ag on Ag(100)

“…We restrict attention to a model for 2D Ag−Au NCs on an Ag(100) surface, a choice motivated by extensive interest in the formation of 3D core−shell and more complex Ag−Au NCs structures. 1,8,14,15,26 Contrasting previous studies of 3D Ag−Au NCs, we will provide precise atomistic-level modeling of selfassembly on the appropriate time scale and also precisely describe post-assembly sintering. See Figure 1 for a schematic of the model.…”

“…Self-assembly of such threedimensional (3D) NCs can be achieved via liquid-phase synthesis 1−3 and of either 2D 4−6 or 3D 7,8 NCs by deposition onto smooth surfaces. In either case, these processes generally occur far from equilibrium, and the resultant structures are usually highly sensitive to the thermally activated kinetics of relaxation (via periphery diffusion, attachment-detachment, and/or intermixing) for the aggregated atoms.…”

Size Selected Clusters on Surfaces

“…This underscores the need for means that allow one to control the size of deposited clusters as a way of tailoring the properties and functions of these nanostructures. Amongst the various methods of cluster deposition, which include conventional molecular beam [6] and wet-chemistry [7] techniques, the soft-landing of size selected gas phase clusters onto supported surfaces is a promising 1 To whom any correspondence should be addressed. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence.…”