The adsorption of amines and other small molecules on platinum surfaces

Abstract

This thesis presents an investigation of the adsorption and thermal decomposition of methylamine, dimethylamine, trimethylamine and s-triazine on Pt(110) and carbon monoxide, nitric oxide and nitrous oxide on Pt(331) using low energy electron diffraction, thermal desorption spectroscopy and angle resolved ultra-violet photoelectron spectroscopy. Thermal desorption experiments show that methylamine decomposes to H2, HCN and C2N2 following thermal treatment. A second minor pathway produces CH4 and N2. H2 and D2 co-adsorption studies reveal that HCN is the product of a decomposition pathway leaving intact H-CN bonds. No C2N2 is observed during the co-adsorption experiments proving that CN exists as individual CN fragments on the surface and not as a surface polymer. These fragments combine with H(a) in excess hydrogen forming a second HCN phase. s-Triazine thermal decomposition also releases HCN, C2N2 and H2. Co-adsorption of s-triazine with H2 and D2 reveal that the main low temperature HCN peak is the result of decomposition leaving intact H-CN bonds while the high temperature shoulder is the result of H(a) and CN(a> recombination. Cyanogen formed during C3H3N3 decomposition is the result of CN(a) recombination. The s-triazine ring has broken down by 500K.