Structure sensitivity of ethylene adsorption on Pt(100): Evidence for vinylidene formation on (1×1) Pt(100)

Electron energy loss spectroscopy (EELS) is used to study ethylene adsorption on the (5×20) and (1×1) reconstructions of Pt(100). It is found that the ethylene adsorbs molecularly on the Pt(100) sample at 120 K independent of whether the sample is in a (5×20) or (1×1) configuration. However, upon heating, the ethylene rearranges to form an ethylidyne intermediate when the sample starts in the (5×20) configuration and a mixture of vinylidene and an acetylenic intermediate when the sample starts in the (1×1) configuration. These results show that the nature of the intermediates which form when ethylene adsorbs on platinum is largely determined by the symmetry of the orbitals available for reaction, as predicted in a related paper.