The Adsorption Behaviors of Perfluoropentacene Molecules on Metallic Surfaces

• Main Authors: Yuan-Yen Lo, 羅元彥
• Other Authors: Chih-I Wu
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/25768979688446913635

博士 === 國立臺灣大學 === 光電工程學研究所 === 101 === We use scanning tunneling microscopy (STM) and X-ray and ultraviolet photoemission spectroscopy (XPS and UPS) to study the adsorption behaviors of perfluoropentacene (PFP) on metallic surfaces. At first, the comparison study of different adsorption behaviors of pentacene (PEN) and PFP molecules on Au(111) surfaces is presented. PEN molecules are mobile underneath the scanning probe tip at elevated positive sample bias and the surface reconstruction of Au(111) is changed by the moving PEN molecules as well. However, PFP molecules are self-assembled and form compact islands on Au(111). Furthermore, strong intermolecular and intramolecular interactions of monolayer PFP are verified by UPS and XPS. Additionally, we compare the different adsorption behaviors of PFP on Au(111), Ag(111) and Cu(111) surfaces. The arrangements of PFP islands on these three surfaces are different and the islands are firmest on Cu(111). The adsorbate-substrate interaction is verified to aid the assembly process. Finally, two different methods, UPS and high order Gundlach oscillation are demonstrated for measuring the work function difference of PFP islands and metallic surfaces. The work function shift measured by high order Gundlach oscillation is not consistent with that measured by UPS at low coverage but is close to that measured by UPS at high coverage. The reason could be UPS reflects the surface dipole but high order Gundlach oscillation reflects the local vacuum level shift and the shift is similar to the vacuum level shift at high coverage with the influence by the arrangement at monolayers.