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Surface chemistry of alanine on Cu{111}: Adsorption geometry and temperature dependence

DOI: 10.1016/j.susc.2014.04.016 DOI Help

Authors: Silvia Baldanza (University of Reading) , Alix Cornish (University of Reading) , Richard E. J. Nicklin (University of Reading) , Zhasmina Zheleva (University of Reading) , Georg Held (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Surface Science , VOL 629 , PAGES 114 - 122

State: Published (Approved)
Published: November 2014

Abstract: Adsorption of l-alanine on the Cu{111} single crystal surface was investigated as a model system for interactions between small chiral modifier molecules and close-packed metal surfaces. Synchrotron-based X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy are used to determine the chemical state, bond coordination and out-of-plane orientation of the molecule on the surface. Alanine adsorbs in its anionic form at room temperature, whilst at low temperature the overlayer consists of anionic and zwitterionic molecules. NEXAFS spectra exhibit a strong angular dependence of the π⁎ resonance associated with the carboxylate group, which allows determining the tilt angle of this group with respect to the surface plane (48° ± 2°) at room temperature. Low-energy electron diffraction (LEED) shows a View the MathML source superstructure with only one domain, which breaks the mirror symmetry of the substrate and, thus, induces global chirality to the surface. Temperature-programmed XPS (TP-XPS) and temperature-programmed desorption (TPD) experiments indicate that the zwitterionic form converts into the anionic species (alaninate) at 293 K. The latter desorbs/decomposes between 435 K and 445 K.

Journal Keywords: Chiral surfaces; Alanine; Copper; Photoelectron spectroscopy; NEXAFS;TPD

Subject Areas: Chemistry

Facility: MAXlab

Added On: 01/02/2016 14:24

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