NEXAFS INVESTIGATIONS ON HIGHLY-ORDERED ULTRATHIN FILMS OF DME-DCNQI ON SINGLE-CRYSTAL SURFACES

DMe-DCNQI forms highly-ordered ultrathin films on various single cryst al surfaces. NEXAFS reveals flat lying molecules for all investigated film thicknesses (up to 40 layers) on nearly all substrates under inve stigation (Ag(111), Ag(100), Cu(100), Cu(111)). The C1s and N1s NEXAFS spectra of these condensed layers show several very sharp resonances. The comparison with the quinoide molecules TCNQ and DMe-BQ shows simi larities, but the electronic structure is too complicated to be interp reted in terms of a building block scheme. NEXAFS data of related char ge transfer salts consist of fewer and much broader resonances in acco rdance with the more delocalized electronic structure of the 'quasimet allic' salts.