Study on the interaction between tetracene and Cu(110) surface.

The electronic structure of tetracene on Cu (110) surface has been studied by using ultraviolet photoemission spectroscopy (UPS). The emission features from the organic molecule are located from 1 to 10 eV below the Fermi level, and they shift in binding energy with increasing the coverage of the organic material. For the surface with multilayer of tetracene, six well-resolved features were found at 1.90, 3.40, 4.70, 5.95, 6.95, and 9.15 eV below the Fermi level, respectively. On the surface with a lower coverage of tetracene, angle-resolved UPS measurements suggest that the molecular plane is parallel to the substrate. Density functional theory calculation confirms the flat-lying adsorption mode and shows that the tetracene molecule prefers to be adsorbed on the long bridge site with its long axis in the [110] azimuth.