Geometrical characterization of pyrimidine base molecules adsorbed on Cu(110) surfaces: XPS and NEXAFS studies

The structures of pyrimidine base molecules of thymine and cytosine adsorbed onto Cu(110) surfaces (theta much less than 1.0 ML and much greater than1.0 ML) have been discussed based on the results of X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). The NEXAFS analysis for azimuthal orientation of molecules on surfaces indicates that the adsorbed molecules are in an upright configuration with their pi plane parallel to the row structure ([1 (1) over bar0] direction), well below saturation coverage (theta similar to 0.2 ML). Based on the chemical shifts observed in XP spectra (N1s, O1s region), the molecules have been determined to interact with surfaces through their nitrogen atom (lone-pair) next to the carbonyl group (C=O). (C) 2003 Elsevier Science B.V. All rights reserved.