title: Cooperative modulation of electronic structures of aromatic molecules coupled to multiple metal contacts.
abstract: We use cryogenic scanning tunneling microscopy and spectroscopy and density-functional theory calculations to inspect the modulation of electronic states of aromatic molecules. The molecules are self-assembled on a Cu(111) surface forming molecular networks in which the molecules are in different contact configurations, including laterally coupled to different numbers of coordination bonds and vertically adsorbed at different heights above the substrate. We quantitatively analyze the molecular states and find that a delocalized empty molecular state is modulated by these multiple contacts in a cooperative manner: its energy is down shifted by ∼ 0.16 eV for each additional lateral contact and by ∼ 0.1 eV as the vertical molecule-surface distance is reduced by 0.1 Å in the physisorption regime. We also report that in a molecule-metal-molecule system the bridging metal can mediate the electronic states of the two molecules.
authors.affiliation: Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: Weihua
authors.initials: W
authors.lastname: Wang
authors.affiliation: Institute of Computational and Theoretical Studies and Department of Physics, Hong Kong Baptist University, Hong Kong, China.
authors.forename: Xingqiang
authors.initials: X
authors.lastname: Shi
authors.affiliation: Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: Shiyong
authors.initials: S
authors.lastname: Wang
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry and Institute of Fine Chemicals, East China University of Science and Technology, Meilong Road 130, Shanghai 200237, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Institute of Computational and Theoretical Studies and Department of Physics, Hong Kong Baptist University, Hong Kong, China.
authors.forename: Michel A
authors.initials: MA
authors.lastname: Van Hove
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry and Institute of Fine Chemicals, East China University of Science and Technology, Meilong Road 130, Shanghai 200237, China.
authors.forename: Pei Nian
authors.initials: PN
authors.lastname: Liu
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, China.
authors.forename: Rui-Qin
authors.initials: RQ
authors.lastname: Zhang
authors.affiliation: Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China.
authors.forename: Nian
authors.initials: N
authors.lastname: Lin