The fabrication of hybrid organic/inorganic semiconductor structures is the subject of a worldwide research e ffort due to possible applications in the fi eld of organic electronics. In particular, the (001) oriented silicon, reconstructed 2 x1, can be used as a template to graft ordered organic arrays via the reaction of molecular functionalities ( π bonds, amines etc.) with the surface silicon dangling bonds in ultra high vacuum (UHV) conditions. However, the most interesting molecular objects (dyes, molecular wires, actuators etc.) directly grafted on a semiconductor surface are multifunctional, which often leads to competitive reactions and subsequently to multiple adsorption geometries. The use of photoemission and X-ray absorption spectroscopy, combined with Density Functional Theory calculations of core excited states, has enabled the precise determination of adsorption geometries of four molecules, which display an amine function : ammonia, ethylenediamine, 1-4 diaminobutane and N,N,N',N' tetramethylethylenediamine (TMEDA). In the TMEDA case, an evolution of the adsorption modes, depending on the exposition and irradiation doses, has also been highlighted.
