Polyaniline and their molecular models are used to analyze electronic modifications of chains caused by the metal surface vicinity. The adsorption of these molecules and their orientation oil platinum surfaces is here characterized by High Resolution Electron Energy Loss Spectroscopy (HREELS) using the selection rules for dipole mechanisms. Adsorbed layers of polyaniline tetramer also exhibit an electronic loss detected around 2.3 eV and here assigned to an intrachain exciton. Adhesion on metallic surfaces mainly involves an effective chemical bond to the surface, where the nitrogen doublet and the quinoïc group play a major role.