Alkali metal adsorption on Al(111)

Growth and electronic structure of alkali-metal adlayers on icosahedralAl70.5Pd21Mn8.5

“…25 So, in the present case, the absence of plasmons below 1 ML indicates that indeed the formation of a dispersed phase occurs. Although the atomic density of the i-Al-Pd-Mn surface is similar to Al͑111͒, where condensed phase formation is reported, 22 the formation of a dispersed phase for i-Al-Pd -Mn might be related to the characteristic quasicrystalline surface morphology. It has been reported that the i-Al-Pd -Mn surface is characterized by terraces of two types; voidrich and void-free.…”

“…At higher coverages, a condensed island formation occurs in most cases. 22 Formation of islands on the Al͑111͒ for such coverages at 140 K is supported by the change in work function and observation of plasmon loss features at submonolayer coverages. 19,25 Based on density functional theory calculations, Neugebauer and Scheffler showed that below 0.1 ML, the Na atoms on Al͑111͒ are homogeneously dispersed, and the adsorbatesubstrate interaction dominates.…”

“…The i-Al-Pd-Mn surface consists of a topmost dense Alrich layer followed by a layer with 50% Al and 50% Pd, and the lateral density of these two layers together is similar to that of Al͑111͒. 26 The adsorption of Na, K, Rb, and Cs on the Al͑111͒ surface at 100 K has been investigated by high resolution core-level spectroscopy by Andersen et al 22 It was found that initially the alkali atoms adsorb at surface defect sites. At higher coverages up to about one third of the maximum submonolayer coverage, the adsorbed alkali metal atoms exist as a dispersed phase.…”

“…Since the adsorbate dipole moment decreases with increasing coverage, the surface corrugation potential primarily dictates the formation of the dispersed phase. 22 The XPS data ͑Figs. 1-3͒ indicate that the formation of a dispersed phase occurs for alkali metals on i-Al-Pd-Mn below 1 ML.…”

“…[15][16][17][18] Different studies on metal substrates have shown that alkali metals grow as a dispersed phase or as condensed islands for the first monolayer ͑ML͒. 15,[19][20][21][22][23][24][25] In this paper, we report on the growth and electronic structure of alkali metal adlayers on the fivefold surface of an i-Al-Pd-Mn quasicrystal using x-ray photoelectron spectroscopy ͑XPS͒, since the core-level BE shift and line shape depend sensitively on the local surroundings and charge transfer. We find a decrease in the BE of the alkali metal core levels and an absence of any plasmon related loss feature until 1 ML saturation coverage.…”