Interaction of size-selected Ag-clusters on Au-thin films: a composition study with in-situ XPS analysis at an elevated temperature

Abstract

In this paper, we describe a novel method of synthesis of bimetallic Ag–Au alloy nanoparticles with an estimated Ag to Au concentration ratio of ∼3:1 by using a gas-aggregation cluster source. The real time chemical changes occurred on the surface of the alloy film during different stages of annealing at an elevated temperature are observed by in-situ x-ray photoelectron spectroscopy analysis. It is found that the concentration of both Ag and Au of the alloy film simultaneously decreases with the increase of the annealing time. The chemical states of the elements present on the surface are analyzed from the HR-XPS data, which are recorded for the dominant elements present on the surface. From the analyses, it is found that a small part of metallic Ag gets oxidized for higher annealing time whereas no trace of oxidation of Au is observed. The surface morphology of the as-deposited and post-annealed alloy films are characterised by FESEM and AFM measurements. Due to thermal diffusion of Ag and Au, resultant narrow size distributions of the bimetallic Ag–Au nanoparticles are observed on the surface. The film morphologies suggest that the evolutions of bimetallic Ag–Au nanoparticles are nearly spherical in shape with an average aspect ratio value of ∼1.5.

Wettability Transition on the Fractal Surface Developed by Size-Selected Ag Nanoclusters

“…From these HR-XPS spectra of core level Ag 3d, the positions of the doublet peaks, that is, Ag 3d 5/2 and Ag 3d 3/2 , are observed at BE values 368.1 and 374.1 eV, respectively. These assigned BE values of Ag cluster aggregates agree with the previously reported values for metallic Ag NPs. − From the literature reports, it is found that the formation of silver oxides causes BE shifts of Ag 3d peak toward a lower value. However, in the present case, we have not noticed any significant BE shifts of Ag 3d peaks which confirms that oxidation of Ag nanostructures does not occur during their deposition.…”

Structure and Reactivity of Active Oxygen Species on Silver Surfaces for Ethylene Epoxidation

“…The three oxygen species represented by peaks with BE lower than 531.5 eV gradually form on the surface as the temperature increases. Based on assignments from previous literature, O 1s having BE values above 532.1 eV are mainly attributed to carbon-containing intermediates. − Therefore, we denote them as O C1 , O C2 , and O C3 , respectively. Because the scope of this work is to discuss oxygen reaction intermediates formed on silver during the oxidation of ethylene, we will not discuss in detail these species.…”

Polynitrogen clusters interaction with water: experimental and theoretical perspectives

“…One common way for generating clusters is to bombard of substrates with laser pulses, electrons and so on [14][15][16][17][18][19][20], which have also been employed to produce nitrogen clusters [21][22][23][24][25][26][27][28][29][30][31][32]. For example, the nitrogen discharges have been used to generate the linear centrosymmetric ground state of the N 4…”