【摘要】 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.更多还原

【Abstract】 Utilizing UHV-STM and organic molecular beam deposition (OMBD), we have studied the adsorption and two-dimensional self-assembly of perfluoropentacene (PFP) on the semimetal Ga film. At low coeverage single PFP molecule exhibits very high mobility. When the coverage increased to 1 monolayer(ML),PFP dimerizaton takes place with disordered arrangement. Delicate annealing leads to the formation of two dimensional self-assembled monolayer: PFP dimers are organized into one-dimensional molecular ribbons arrays, in which PFP dimers have the brick-wall packing. In the high-resolution STM images, each PFP molecule exhibits two round protrusions with one brighter than the other,and the neighboring two PFP molecules have the opposite brightness polarization, indicating each PFP molecule has the net dipole moment, and each PFP dimer has the net quadrople moment. Therefore the formation mechanism of PFP dimers can be attributed phenomenally to the electrostatic attraction between the opposite dipole, and the brick-wall packing of PFP dimers can be attributed to the electrostatic repulsive force between the same quadrople moments.更多还原