Using photon impinging effect to study the disparate anchoring stabilities of polar-organic molecules adsorbed on bulk and thin-film metal surfaces
Kowsalya Arumugam1*, Hong-Ming Chen1, Jing-Huan Dai1, Mau-Fu Gao1, Abhishake Goyal1, Meng-Kai Lin1, Yasuo Nakayama3, Tun-Wen Pi2, Sebastian Metz7, Theodoros A. Papadopoulos8, S-J Tang1,2
1Department of Physics and Astronomy, National Tsing Hua University, Hsinchu, Taiwan
2National Synchrotron Radiation Research Center, Hsinchu, Taiwan
3Department of Pure and Applied Chemistry, Tokyo University of Science, Chiba, Japan
4Department of Physics, University of Illinois, Illinois, USA
5Center for Frontier Science, Chiba University, Inage-ku, Japan
6Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Japan
7Scientific Computing Department, STFC Daresbury Laboratory, Warrington, UK
8Department of Natural Sciences, University of Chester, Chester, UK
* Presenter:Kowsalya Arumugam,
The behaviors of polar organic molecules, chloroaluminum phthalocyanine (ClAlPc), upon photon-irradiation effects were investigated to realize their adsorption stabilities on the Ag(111) thin film and crystal. Angle-resolved photoelectron spectroscopy (ARPES) was mainly employed to measure the photon-flux dependence of molecular energy states (MES) and vacuum level shift (VLS) for 1-ML ClAlPc in Cl-down configurations, indicating a consistent trend that ClAlPc in Cl-down configuration is evidently more stable on the Ag thin-film surface than on the corresponding surface of the Ag bulk crystal. The intermediate adsorption state, tilted configuration, during the photon impinging, is identified by the large positive VL shifts and broad line shapes to infer the flipping mechanism from Cl-down to Cl-up configuration. The strained effect on Ag thin films from the underlying, 30% lattice mismatched, Ge(111) substrate is considered to cause the enlarged vacancy sites of Ag-film surfaces, that help anchor Cl-down configuration more tightly, as confirmed by the first-principles calculations.

Keywords: Chloroaluminium phthalocyanine, photon irradiation effect, ARPES, Flipping Mechanism