Effect of substrate on interfacial electronic properties of ferrocene thin films

Ferrocene molecular thin films on conducting substrates have potential for novel molecular electronic devices. Based on X-ray absorption spectroscopy and photoemission spectroscopic techniques, we have analyzed electronic properties of ferrocene thin films nano-junctions on layered highly oriented pyrolytic graphite (HOPG) and epitaxially grown graphene on Ni(111) substrates. Fe L edge analysis indicates that layered structure of HOPG has significant impact on room temperature desorption of ferrocene as compared to grapheme on Ni(111) substrate. C-K edge XAS spectrum reveal that ferrocene molecules do not have preferred orientation for adsorption on grapheme grown on Ni(111) substrate. In addition, X-ray absorption spectroscopy (XAS) reveals that there is no change in iron atom oxidation state suggesting that ferroence interaction is feeble with grapheme on Ni(111) substrate and HOPG.