XPS, NEXAFS and theoretical study of phenylacetylene adsorbed on Cu(100)

The adsorption dynamics and geometry of phenylacetylene (PA) on Cu(1 0 0) was investigated by means of X-ray photoemission (XPS), near edge X-ray absorption (NEXAFS) spectroscopies and by quantum chemical calculations. The clean metal surface was exposed to PA vapors and the C1s core level spectrum evolution was monitored by means of time-resolved XPS measurements. Photoemission (C1s) and absorption (C K-edge) spectra were recorded both in monolayer and multilayer regimes; polarization-dependent NEXAFS investigations were carried out on the PA monolayer at room temperature. The experimental results have been interpreted with the help of quantum chemical calculations: density functional theory (DFT) plane-wave based calculations for the optimization of the interaction geometry of PA on a two layered (1 0 0)-slab of Cu atoms using periodic boundary conditions and ab initio simulation of the XPS spectrum for a small cluster including PA in the optimized adsorbate geometry and the two Cu atoms more directly involved in the adsorption. (C) 2004 Elsevier B.V. All rights reserved.