XPS and STM studies of simple and complex molecules at Cu(110) and Ag(111) surfaces

Richards, Darran 2007. XPS and STM studies of simple and complex molecules at Cu(110) and Ag(111) surfaces. PhD Thesis, Cardiff University.

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Abstract

The adsorption of aniline at a clean and oxidised Cu(110) surface has been studied using STM and XPS at 295K. Adsorption at a partially oxidised surface results in formation of a phenyl imide. Co-adsorption of aniline and oxygen resulted in a closer packed surface. Concentrations calculated using XPS were twice that of concentrations calculated using unit cells determined by STM. Two models were proposed to account for this discrepancy. The first involved alternating parallel and perpendicular phenyl rings with respect to the surface. The favoured proposal on a basis of the steric hindrance involves parallel pi-stacking of the phenyl rings. The interaction of gaseous malonyl dichloride (C3H2CI2O2) with clean Cu(110) and partially oxidised Cu(110) surface has been studied. At low temperatures, malonyl dichloride physisorbed at the surface. Malonyl dichloride will only adsorb at a Cu(110) surface in the presence of oxygen at room temperature. This indicates that oxygen activates a reaction with malonyl dichloride at the Cu(110) surface. The interaction of melamine with clean and oxidised Cu(110) and clean Ag(111) has been studied. Melamine adsorption at a Cu(110) and Ag(111) surface resulted in molecular adsorption. Adsorption of melamine and malonyl dichloride at a Cu(110) surface resulted in a reaction occurring leading to CI adsorption but no effect on melamine. The binding energies do suggest that melamine is adsorbed molecularly at the surface but chlorine was also present. A co-adsorption of melamine and malonyl dichloride at an Ag(111) surface produced a surface with melamine molecularly adsorbed and also chlorine present. Pre-adsorbed melamine was exposed to cesium. Cesium atoms adsorbed on the supramolecular network created by melamine at an Ag(111) surface. The interaction of biphenyl dicarboxylic acid (BPDCA) with clean and oxidised Cu(110) and Ag(111) surfaces has been studied. Chemisorption occurred at a clean Cu(110) surface. Predominantly, the substrate-adsorbate interaction was too strong for any supramolecular structures to be formed. The adsorption of BPDC A at an Ag(111) surface resulted in various structures that were affected by concentration. Both the carboxylic groups and the phenyl rings played a part in the creation of the various supramolecular structures at the surface. The weaker substrate decreased the adsorbate-substrate interactions and allowed more freedom for intermolecular interactions.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Chemistry
Subjects:	Q Science > QD Chemistry
ISBN:	9781303215001
Date of First Compliant Deposit:	30 March 2016
Last Modified:	31 Jan 2020 05:06
URI:	https://orca.cardiff.ac.uk/id/eprint/54876

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