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Benzene ; Chemisorption ; Near edge extended X-ray absorption fine structure (NEXAFS) ; Platinum ; PMDA
Abstract:
Dipole selection rules require the π*-resonances, which dominate X-ray absorption spectra for planar aromatic molecules, to have zero intensity for X-ray photons linearly polarized in the molecular plane. For molecules adsorbed in a flat geometry on metal surfaces, however, very often considerable intensities are observed for s-polarized light. We will present experimental and theoretical evidence that for two molecules, benzene and pyromellitic dianhydride (PMDA) adsorbed on Pt(111), this anomalously weak linear dichroism is not due to molecular disorder as assumed previously but arises from molecular rehybridisation caused by out-of-plane molecular distortions.
