On the interpretation of valence band photoemission spectra at   organic-metal interfaces
  Adsorption of organic molecules on well-oriented single crystal coinage metal surfaces fundamentally affects the energy distribution curve of ultra-violet photoelectron spectroscopy spectra. New features not present in the spectrum of the pristine metal can be assigned as "interface states" having some degree of molecule-substrate hybridization. Here it is shown that interface states having molecular orbital character can easily be identified at low binding energy as isolated features above the featureless substrate sp-plateau. On the other hand much care must be taken in assigning adsorbate-induced features when these lie within the d-band spectral region of the substrate. In fact, features often interpreted as characteristic of the molecule-substrate interaction may actually arise from substrate photoelectrons scattered by the adsorbates. This phenomenon is illustrated through a series of examples of noble-metal single-crystal surfaces covered by monolayers of large pi-conjugated organic molecules. 
L. Giovanelli, F. C. Bocquet, P. Amsalem, H.-L. Lee, M. Abel, S.   Clair, M. Koudia, T. Faury, L. Petaccia, D. Topwal, E. Sa...
cond-mat.mtrl-sci cond-mat.mes-hall physics.chem-ph