Here we present detailed investigations of UV-photoinduced dimerization of anthracene substructures without solvent environment at the level of molecular monolayers prepared on a surface. Monolayers prepared on silicon(100) substrates were analyzed by means of X-ray photoelectron spectroscopy (XPS) in the valence band region revealing significant changes in the carbon C 2s region (11-20 eV). SVWN DFT calculations were performed to understand the influence of the structural changes by dimerization. The geometric structure of the functionality was retrieved through B3LYP DFT calculations, which were performed ahead of the SVWN DFT ones, and the result of these calculations matches with the measured vibration signature. FTIR investigations of polybutadiene (PBD) volume backboned functionality were performed before and after irradiation.