Molecular orbital imaging of cobalt phthalocyanine on native oxidized copper layers using STM

To observe molecular orbitals using scanning tunneling microscopy, well-ordered oxidized layers on Cu(001) were fabricated to screen the individual adsorbed cobalt phthalocyanine (CoPc) molecules from the electronic influence of the metal surface. Scanning tunneling microscope images of the molecule on this oxidized layer show similarities to the orbital distribution of the free molecule. The good match between the differential conductance mapping images and the calculated charge distribution at energy levels corresponding to the frontier orbitals of CoPc provides more evidence of the screening of the oxidized layer from interactions between the metal surface and supported molecules. -- Highlights: ► STM is a powerful tool to depict molecular orbitals, a basic concept of chemistry. ► Native copper oxide layer was fabricated for adsorption of cobalt phthalocyanine. ► Detailed orbitals of CoPc were successfully observed for the 1st time by STM. ► The effect of the layer is explained by DFT quantum mechanical computations.