title: Pentacene on Au(1 1 1), Ag(1 1 1) and Cu(1 1 1): From physisorption to chemisorption.
abstract: We measured the electronic and the molecular surface structure of pentacene deposited on the (1 1 1)-surfaces of coinage metals by means of ultraviolet photoelectron spectroscopy (UPS) and low-energy electron diffraction (LEED). Pentacene is almost flat-lying in monolayers on all three substrates and highly ordered on Au(1 1 1) and on Cu(1 1 1). On Ag(1 1 1), however, weak chemisorption leads to almost disordered monolayers, both, at room temperature and at 78 K. On Cu(1 1 1) pentacene is strongly chemisorbed and the lowest unoccupied molecular orbital becomes observable in UPS by a charge transfer from the substrate. On Ag(1 1 1) and Cu(1 1 1) multilayers adopt a tilted orientation and a high degree of crystallinity. On Au(1 1 1), most likely, also in multilayers the molecular short and long axes are parallel to the substrate, leading to a distinctively different electronic structure than on Ag(1 1 1) and Cu(1 1 1). Overall, it could be demonstrated that the substrate not only determines the geometric and electronic characteristics of molecular monolayer films but also plays a crucial role for multilayer film growth.
authors: Institute of Functional Nano & Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, People's Republic of China.
authors: Meng-Chao
authors: MC
authors: Lu
authors: Rong-Bin
authors: RB
authors: Wang
authors: Ao
authors: A
authors: Yang
authors: Steffen
authors: S
authors: Duhm