Molecular orientation of 2-mercaptobenzoxazole adsorbed on Cu(1 0 0) surface

• Published in: Surface science 2005-03, Vol.578 (1), p.136-141
• Main Authors: Bussolotti, F., D’Addato, S., Allegretti, F., Dhanak, V., Mariani, Carlo
• Format: Article
• Language: English
• Subjects: Chemisorption; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Copper; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Low index single crystal surfaces; Near edge X-ray adsorption fine structure (NEXAFS); Physics; Self-assembly
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2005.01.023

The long range ordered p(2 × 2) self-assembled monolayer formed by dosing 2-mercaptobenzoxazole (MBO, C 7H 5NOS) on the Cu(1 0 0) surface at room temperature has been investigated by means of near edge X-ray adsorption fine structure (NEXAFS) technique at the sulphur K-edge. NEXAFS S–K-edge spectra have been recorded at different incident photon angles with respect to the Cu(1 0 0) surface, using linearly polarised synchrotron radiation. A clear spectral feature has been observed close to the absorption edge, with higher intensity at grazing incidence, assigned to the σ*(S–C) resonance, corresponding to the transition from the S 1s core level to the σ*(S–C) antibonding molecular state. The angular dependence of the σ*(S–C) resonance intensity clearly indicates that the S–C axis is nearly perpendicular to the surface (13° ± 13°), confirming the major role of S in bonding to the surface, and the influence of the π–π interaction between the molecules in driving the almost upright position at saturation coverage.