中国物理B ›› 2002, Vol. 11 ›› Issue (8): 839-845.doi: 10.1088/1009-1963/11/8/317

• 8000 CROSSDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY • 上一篇    

Adsorption geometry of glycine on Cu(001) determined with low-energy electron diffraction and scanning tunnelling microscopy

葛四平, 赵学应, 盖峥, 赵汝光, 杨威生   

  1. The Mesoscopic Physics Laboratory and Department of Physics, Peking University, Beijing 100871, China
  • 收稿日期:2002-02-25 修回日期:2001-12-19 出版日期:2005-06-12 发布日期:2005-06-12
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 10134030).

Adsorption geometry of glycine on Cu(001) determined with low-energy electron diffraction and scanning tunnelling microscopy

Ge Si-Ping (葛四平), Zhao Xue-Ying (赵学应), Gai Zheng (盖峥), Zhao Ru-Guang (赵汝光), Yang Wei-Sheng (杨威生)   

  1. The Mesoscopic Physics Laboratory and Department of Physics, Peking University, Beijing 100871, China
  • Received:2002-02-25 Revised:2001-12-19 Online:2005-06-12 Published:2005-06-12
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 10134030).

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摘要： Using low-energy electron diffraction (LEED) and scanning tunnelling microscopy (STM) it has been found that glycine molecules adsorbed on Cu(001) can form but only the (2×4) and c(2×4) superstructures. On the basis of the missing LEED spots of the surface, it has been concluded that: each (2×4) unit cell consists of two molecules, one being the mirror image of the other; the C－C axis of both molecules lies in the mirror plane of the Cu substrate without a significant shift and twist from the plane; and the two O atoms of the carboxylate group of both molecules locate at the same height level without significant buckling. According to these conclusions, a structural model has been proposed for the (2×4) superstructure (a model for the c(2×4) superstructure already exists). We argue that the (2×4) and c(2×4) superstructures must have similar specific surface free energy, that their hydrogen bonds must be of N-H-OII type, and that their local adsorption geometry must be similar or even the same. The advantage of combining STM with LEED to determine surface structures is clearly demonstrated.

Abstract: Using low-energy electron diffraction (LEED) and scanning tunnelling microscopy (STM) it has been found that glycine molecules adsorbed on Cu(001) can form but only the (2×4) and c(2×4) superstructures. On the basis of the missing LEED spots of the surface, it has been concluded that: each (2×4) unit cell consists of two molecules, one being the mirror image of the other; the C－C axis of both molecules lies in the mirror plane of the Cu substrate without a significant shift and twist from the plane; and the two O atoms of the carboxylate group of both molecules locate at the same height level without significant buckling. According to these conclusions, a structural model has been proposed for the (2×4) superstructure (a model for the c(2×4) superstructure already exists). We argue that the (2×4) and c(2×4) superstructures must have similar specific surface free energy, that their hydrogen bonds must be of N-H-OII type, and that their local adsorption geometry must be similar or even the same. The advantage of combining STM with LEED to determine surface structures is clearly demonstrated.

Key words: amino acids, surface adsorption, low-energy electron diffraction, scanning tunnelling microscopy (STM)

中图分类号:  (Adsorption kinetics ?)

  • 68.43.Mn
68.37.Ef (Scanning tunneling microscopy (including chemistry induced with STM)) 68.43.Fg (Adsorbate structure (binding sites, geometry)) 68.47.De (Metallic surfaces)