In this project the physical and chemical properties of ultra-thin films of a new class of functionalized organic molecules with photosensitive end groups will be investigated. In particular we will focus on the structure, stability and reactivity of these layers and explore the possibility to form well ordered self-assembled monolayers (SAMs). The reactivity of the self organized films and the possibility to change their reactivity by UV irradiation will be investigated for three different cases: a) Adsorption of gaseous molecules like water, small hydrocarbons and amines on the SAM, which is important for the application of such films for sensors and photolithography. b) Evaporation and film formation of metals, like gold and aluminum, on the SAM surface because of its relevance for the fabrication of contact electrodes in organo-electronic devices. c) Formation of organic heterolayers by evaporation of aromatic organic molecules, e.g. oligo-phenylenes, onto the SAM, which is important for the realization of sandwich layers in organic electronics. We will perform these investigations under well defined ultra-high vacuum conditions and a variety of surface science techniques will be applied, which allows the in-situ study of the growth kinetics, film structure and reactivity under controlled conditions. The films will be mainly prepared by physical vapour deposition (PVD), but surface science studies on films which are grown ex-situ by the traditional route from solution will also be performed. Surface analytical techniques like X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), thermal desorption spectroscopy (TDS) and infra-red absorption spectroscopy (RAIRS) will be the main tools to study the chemical composition, structure, chemical reactivity and UV sensitivity of the SAMs. In collaboration with partners we will utilize scanning electron microscopy (SEM), atomic force microcopy (AFM), scanning tunneling microscopy (STM) and X-ray diffraction (XRD) to get further information on the structure and morphology of the functionalized organic films. From these investigations we expect to obtain a deeper understanding of the underlying principles of SAM formation for this specific class of photosensitive organic molecules, which will open new perspectives in the application of such films, e.g., for selective sensing devices, patterning by photo lithography, protective coatings and for organo-electronic device fabrication in general.