The scattering of surface state electrons at Lander-type molecules on Cu(111) was investigated, using scanning tunneling microscope (STM) at low temperature. Specific information concerning the electronic interation of the different internal groups of the molecule with the surface was obtained. The molecules were sublimed from a Knudsen cell and the dosage was checked via a quartz-crystal microbalance. The central moleculare wire of the molecule, although decoupled from the surface by spacer groups and therefore not visible in the a STM images, was found to be the main one responsible for scattering of surface state electrons.