标题：Pits and adatoms at the interface of 1-ML C84/Ag (111)
作者机构：Department of Physics, Zhejiang University, Hangzhou 310027, China;Department of Applied Physics, Shandong University of Science
通讯作者地址：[Li, HN]Zhejiang Univ, Dept Phys, Hangzhou 310027, Zhejiang, Peoples R China.
摘要：We prepare a well-defined C-84 monolayer on the surface of Ag (111) and study the geometric structure by scanning tunneling microscopy (STM). The C-84 molecules form a nearly close-packed incommensurate R30 degrees lattice. The lattice is long-distance ordered with numerous local disorders. The monolayer exhibits complex bright/dim contrast; the largest height difference between the molecules can be greater than 0.4 nm. Annealing the monolayer at 380 degrees C can desorb part of the molecules, but more than sixty percent molecules stay on the Ag (111) surface even after the sample has been annealed at 650 degrees C. Our analyses reveal that the 7-atom pits form beneath many molecules. Some other molecules sit at the 1-atom pits. Ag adatoms (those removed substrate atoms, accompanying the pit formation) play a very important role in this system. The adatoms can either stabilize or destabilize the monolayer, depending on the distribution manner of the adatoms at the interface. The distribution manner is determined by the co-play of the following factors: the dimension of the interstitial regions of the C-84 overlayer, the number of the adatoms, and the long-distance migration of part adatoms.