Abstract
This thesis investigates the interaction between the two-dimensional metal thin film and the adsorbed organic molecules to examine the various effects on the properties of organic thin film such as quantum size effect, deposition rate, and post annealing. The main experimental tool is angle-resolved photoelectron spectroscopy to map the electronic structures of the sample. Tetratetracontance (TTC) on Ag film is prepared to study the physisorption, and the interfacial properties such as dielectric constant of 1 monolayer TTC. The adsorption of TTC molecules changes the phase shift at the vacuum-Ag interface, resulting in the energy shift of the quantum-well states of the Ag film. The Ag thickness-dependent energy shift of quantum-well states directly reveals the influence of the quantum size effect, and helps the derivation of a model to also extract the dielectric properties of monolayer TTC. Chemisorption of CuPc on Ag film is studied also using Ag quantum well stat for probing. The thickness-dependent energy position of the gap state is explained by the mediation of the interaction from the bulk Ge to the top CuPc layer though the Ag quantum-well states. Consequently, tuning energy level alignment at the CuPc-Ag interface could be fulfilled by changing the thickness of Ag film. This work demonstrates that when the bulk metal crystal is replaced by a uniform metal thin film, the two-dimensional quantum-well state could modify the interfacial electronic structures, which have no counterparts at the organic-bulk crystal interface. Polar organic molecule, ClAlPc, on Ag film is examined to realize the effects that determine the adsorption configuration in the context of chemisorption. We find the deposition rate and the post annealing process lead two different molecular configurations, Cl-down or Cl-up, respectively. These two different configurations render the interfacial energy level alignment to differ for about 0.3 eV. Moreover, both experimental results and calculations based on realistic model of ClAlPc on Ag(111) suggest that two different charge-transfer channels corresponding to the two configurations are the key physical mechanism for the different behaviors of the two adsorption configurations.