The here presented thesis has two focus points: a)the interaction of pi-conjugated organic molecules with selected substrates and b) writing a program for the output and visualization of photo emission data obtained with the SES 200 analyzer. The A1 control program of the group's SES 200 electron energy analyzer has a data file structure, making further data evaluation difficult. In the course of this thesis a program has been developed that allows for a simple and versatile output of obtained ARUPS and XPS data. It allows to normalize and export the spectra and to correct for the analyzer transmission. In addition three different styles for a first data visualization have been included.In the second part the tuning of the interaction strength between Perylenetetracarboxylic dianhydride (PTCDA) and silver [Ag(100)] with potassium chloride (KCl) has here investigated with angle resolved ultraviolet photoelectron spectroscopy (ARUPS) and low energy electron diffraction (LEED). For this KCl has been evaporated on the Ag(100) surface and characterised with LEED and ARUPS. After this, the PTCDA was evaporated on the known KCl films. Here we have tried to decouple the PTCDA molecules from the silver substrate by a KCl interlayer for increasing KCl thicknesses. This was monitored by the lowest unoccupied molecular orbital (LUMO) being filled or not. The third topic has been the basic charactaristics of zinc-phtalocyanine (ZnPc) on clean and (2x1)Oxygen reconstructed copper, with ARUPS under different growth conditions. The ZnPc was evaporated on the substrate at two substrate temperature conditions (room temperature and liquid nitrogen cooled). The valence band electron structure of the ZnPc films was studied for increasing ZnPc coverages. In addition heating series preformed subsequently gave information's on the thermal stability and the monolayers. The present data has been evaluated using the program written in the course of the thesis.