Structure Determination of Au on Pt(111) Surface: LEED, STM and DFT Study

Abstract

Low-energy electron diffraction (LEED), scanning tunneling microscopy (STM) and density functional theory (DFT) calculations have been used to investigate the atomic and electronic structure of gold deposited (between 0.8 and 1.0 monolayer) on the Pt(111) face in ultrahigh vacuum at room temperature. The analysis of LEED and STM measurements indicates two-dimensional growth of the first Au monolayer. Change of the measured surface lattice constant equal to 2.80 Å after Au adsorption was not observed. Based on DFT, the distance between the nearest atoms in the case of bare Pt(111) and Au/Pt(111) surface is equal to 2.83 Å, which gives 1% difference in comparison with STM values. The first and second interlayer spacing of the clean Pt(111) surface are expanded by +0.87% and contracted by −0.43%, respectively. The adsorption energy of the Au atom on the Pt(111) surface is dependent on the adsorption position, and there is a preference for a hollow fcc site. For the Au/Pt(111) surface, the top interlayer spacing is expanded by +2.16% with respect to the ideal bulk value. Changes in the electronic properties of the Au/Pt(111) system below the Fermi level connected to the interaction of Au atoms with Pt(111) surface are observed.

Materials for hot carrier plasmonics [Invited]

“…For the Al-Ga alloy (equiatomic composition) [26], the distributions are relatively flat but slightly favor hot hole collection. For Au-Pt alloy (Au atoms sitting in the most stable hollow FCC positions on the Pt (111) lattice) [22], the EDOS is close to the ideally modified profile for holes, where there is high density for occupied states below the Fermi level, but low density for vacant states above the Fermi level. This profile would best facilitate hot hole extraction regardless of the photon energy because the hot hole distribution peak will always be as far as possible from the Fermi energy.…”

“…Included are transition metals and rare-earth metals, which involve more complicated EDOS profiles due to their complex band structures. For Pt [22], due to the large number of occupied states below the Fermi level, the peak for hot holes is still much further from the Fermi level than that for hot electrons, making it better suited for hot hole collection than hot electron collection. For the other metals listed here, a high EDOS appears on both sides of the Fermi level.…”

“…Further, nearly perfect absorption has been experimentally achieved in a number of plasmonic and metamaterial structures [4,8,16,17]. Secondly, EDOS data are taken from the literature [18][19][20][21][22][23][24][25][26][27][28][29][30]. Combining the EDOS with the Fermi distribution function yields the transition probability and hence the resulting hot carrier distribution.…”

Indirect Detection of the Light Emission in the Local Tunnel Junction

“…Typical STM image of the sample surface after the annealing is shown in Figure a. The step height reads 0.2 nm, which corresponds to 1 monolayer of Au according to the literature …”

“…The step height reads 0.2 nm, which corresponds to 1 monolayer of Au according to the literature. [28] The parameters of the annealing procedure are of great importance for the studied structures. As reported previously, [29] heating of mica to the temperatures above 225 C is accompanied by diffusion of contaminants from the interlayer space, in particular, potassium.…”