Physical Review Letters · 1998 · 85 citations · 14 references
Natural SciencesChemistryPhysicsSpectroscopySurface ChemistrySurface ScienceAdsorption At InterfacesInfrared SpectroscopySurface AdsorptionSurface CrystallographySurface PhysicsSurface SpectroscopyAdsorbate CharacterizationAdsorbate OrderingAdsorption On Metal SurfacesAzimuthal AnisotropyMolecular Orientation At SurfacesReflectance SpectroscopySurface Adsorbate OrderingSurface Reflectance Spectroscopy
We have determined the azimuthal orientation of an adsorbate on a metal surface from an intramolecular-transition-derived feature in reflectance anisotropy spectroscopy (RAS). Adsorption of 9-anthracene carboxylic acid onto $p(2\ifmmode\times\else\texttimes\fi{}1)\mathrm{O}/\mathrm{Cu}\left(110\right)$ led to an ordered structure with a strong (2%), derivativelike feature at 4.5 eV. Fresnel theory predicts the measured intensity, functional behavior, and sense of the RAS signal for the molecule aligned along [110]. IR measurements confirm that the molecular plane is perpendicular to the surface and STM measurements support the azimuthal orientation. We reassign the sense of the clean Cu(110) surface RA spectrum.
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