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利用超高真空扫描隧道显微镜(UHV-STM)和有机分子束沉积(OMBD)方法研究了全氟并五苯(perfluoropentancene,PFP)分子在半金属Ga表面的吸附和两维自组装.在低覆盖度下单个PFP分子在Ga表面上表现出很高的迁移性.在1分子单层(monolayer,ML)时PFP分子发生二聚化并在Ga表面上无序排列.轻度热退火可导致PFP两维自组装:二聚体排列为高度有序的一维分子带阵列,带中PFP二聚体排列为砖墙(brickwall)结构.在高分辨STM图中,PFP分子两端出现亮暗相反的圆形突起,并且相邻分子的亮暗极性相反,表明PFP分子带有电偶极矩,PFP二聚体带有电四极矩.因此,PFP分子二聚体的形成机制可唯像解释为反向电偶极矩之间的静电吸引作用;二聚体的砖墙排列结构可归结为同向电四极矩之间的静电排斥作用.
The adsorption and two-dimensional self-assembly of perfluoropentancene (PFP) molecules on semimetallic Ga surface were investigated by UHV-STM and OMBD methods. The individual PFP molecules exhibit a high mobility on the Ga surface. The PFP molecules dimerize and disorganize on the Ga surface in a monolayer (ML) .Mild thermal annealing can lead to PFP Two-dimensional self-assembly: dimers are arranged in a highly ordered one-dimensional molecular band array with PFP dimers arranged in a brickwall structure. In high-resolution STM images, both ends of the PFP molecule appear bright and dark Of the circular protrusions, and the adjacent molecules of the light and dark polarity opposite, indicating that PFP molecules with electric dipole moment, PFP dimer with electric quadrupole moment.Therefore, PFP molecular dimer formation mechanism can be like It is interpreted as the electrostatic attraction between the opposite electric dipole moments. The structure of the dimer’s brick wall can be attributed to the electrostatic repulsion between the quadrupole moments.