Auger spectroscopy and low-energy electron diffraction studies of the chemisorption of unsaturated molecules by the (100) surface of platinum

High resolution Auger emission studies of a clean (100) surface of platinum and its chemisorption of carbon monoxide, ethylene, vinyl chloride, vinyl fluoride, 1,1-difluoroethylene, butadiene, propene and hexafluoropropene are described. The Auger transition energies provide no general evidence for ‘chemical shifts’ but chemisorption leads to a significant modification of some Auger transition probabilities involving platinum-valence electrons. X-ray-induced electron emission spectroscopy shows that adsorption of carbon monoxide leads to a net electron transfer from the platinum to the ligand. The surface configuration of adsorbed carbon monoxide is defined by a Fourier analysis of l. e. e. d. data. There are both terminal and bridging carbonyl groups; the platinum-carbon (terminal) bond length is 0⋅16 nm while the bridging carbonyl ligand has four equal Pt-C distances of 0.24 nm.