甘氨酸在Cu(111)表面吸附的扫描隧道显微镜研究

ADSORPTION OF GLYCINE ON Cu(111) INVESTIGATED BY SCANNING TUNNELING MICROSCOPY

用超高真空扫描隧道显微镜 (UHV -STM)研究了室温下甘氨酸在Cu( 111)表面的吸附行为 .实验发现 ,在低覆盖度下甘氨酸分子在表面表现为二维气体 .当覆盖度足够高时 ,甘氨酸分子最终会形成二维固相结构 ,为 ( 4× 8)超结构 .针对这种结构提出了两种可能的结构模型 ,模型能够很好地解释STM图 .当覆盖度介于气相和固相之间时 ,根据蒸镀条件和退火条件的不同 ,表面可能出现两种不同的中间相 ,一种为条纹结构 ,另一种为六角结构 。

The adsorption behaviours of glycine on Cu(111) have been investigated under ultra-high vacuum conditions at room temperature using scanning tunneling microscopy(STM). At lower coverage, it has been found that glycine can form only a two-dimensional gas phase on the Cu ( 111) surface. When the coverage is high enough, glycine will form a two-dimensional solid phase, i.e., the (4 x 8) superstructure. Two possible models have been proposed for the (4 x 8) superstructure. The models can explain STM images well. In addition, in a coverage range between those of the gas and solid phases, two intermediate phases are formed depending on different conditions of deposition and annealing. One is a stripe structure; the other is a hexagonal structure. To understand these intermediate phases further investigations are needed.