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.
作者利用扫描隧道显微镜 (STM)详细研究了室温下Na原子在Si(111) (7× 7)表面的吸附 .对STM图像及功函数变化的分析表明 ,当Na原子覆盖度小于临界覆盖度 (0 .0 8ML)时 ,Na原子具有类气态的性质并可以在一个吸附能阱中快速移动 .从STM图像可看出这种移动导致的对比度调制 .在临界覆盖度以上 ,Na原子自组装形成团簇阵列 .第一原理模拟计算的结果与作者的实验结论很好吻合 .
Quasicrystals and nano-quasicrystals were discovered in annealed Zr-Al-Ni-Cu-Ag bulk metallic glasses by systematic transmission electron microscopic (TEM) analysis. Selected area electron diffraction (SAED) and micro-beam diffraction patterns corresponding to five-, three-, and two-fold rotational symmetry were obtained. It demonstrates that the precipitated phases in the primarily devitrified bulk metallic glasses are icosahedral quasicrystalline phases. The formation of nano-quasicrystals is attributed to the high nucleation density and nucleation rate. Moreover, the addition of Ag benefits the formation of the nano-quasicrystalline phase. The discovery of icosahedral phases directly reflects an intrinsic relationship between the bulk metallic glasses and the icosahedral structure.
1 Theory of Scanning Probe Microscopy.- 1.1 Introduction.- 1.2 Scanning Tunneling Microscopy.- 1.3 Frictional Force Microscopy.- 1.4 Dynamic-Mode Atomic Force Microscopy.- 1.5 Non-Contact Mode Atomic Force Microscopy.- 1.6 Conclusion.- References.- 2 The Theoretical Basis of Scanning Tunneling Microscopy for Semiconductors - First-Principles Electronic Structure Theory for Semiconductor Surfaces.- 2.1 Introduction.- 2.2 Computational Methods.- 2.3 Surface Structures.- 2.4 Surface Dynamics.- References.- 3 Atomic Structure of 6H-SiC (0001) and (000$$\bar{1}$$).- 3.1 Introduction.- 3.2 Surface Preparation.- 3.3 Surface Structure of 6H-SiC (0001) and (000$$\bar{1}$$).- 3.4 Surface Phonons of 6H-SiC (0001).- 3.5 Effect of Surface Polarity for Gallium Adsorption onto 6H-SiC Surfaces.- 3.6 Conclusions.- References.- 4 Application of Atom Manipulation for Fabricating Nanoscale and Atomic-Scale Structures on Si Surfaces.- 4.1 Introduction.- 4.2 Experimental Aspects.- 4.3 Property Changes in the Si(111)?7x7 Surface.- 4.4 Properties of Dangling Bonds on the Si(100)?2x1?H Surface.- 4.5 Interaction of Adsorbates with Dangling Bonds on Si(100)?2x1?H Surfaces and Atomic Wire Fabrication.- 4.6 Conclusion.- References.- 5 Theoretical Insights into Fullerenes Adsorbed on Surfaces: Comparison with STM Studies.- 5.1 Introduction.- 5.2 Fullerene Research Background.- 5.3 Universal Features of C60 and C70 STM Images.- 5.4 Dipole Field Caused by Charge Transfer.- 5.5 Photo-Induced Excited States.- 5.6 Conclusion.- Appendix: All-Electron Mixed Basis Approach.- References.- 6 Apparent Barrier Height and Barrier-Height Imaging of Surfaces.- 6.1 Introduction.- 6.2 Properties of Barrier Height.- 6.3 Measurements of Barrier Height.- 6.4 Barrier-Height Imaging.- 6.5 Applications of BH Imaging.- References.- 7 Mesoscopic Work Function Measurement by Scanning Tunneling Microscopy.- 7.1 Introduction.- 7.2 Work Function.- 7.3 Experimental Techniques.- 7.4 Results.- 7.5 Conclusion.- References.- 8 Scanning Tunneling Microscopy of III-V Compound Semiconductor (001) Surfaces.- 8.1 Introduction.- 8.2 Semiconductor Surface Reconstruction.- 8.3 GaAs(001) As-Rich Surface.- 8.4 GaAs(001) Ga-Rich Surface.- 8.5 Other Arsenide (001) Surfaces.- 8.6 Phosphide, Antimonide and Nitride (001) Surfaces.- 8.7 Conclusions.- References.- 9 Adsorption of Fullerenes on Semiconductor and Metal Surfaces Investigated by Field-Ion Scanning Tunneling Microscopy.- 9.1 Introduction.- 9.2 Experiment.- 9.3 Results and Discussions on Semiconductor Substrates.- 9.4 Results and Discussions on Metal Substrates.- 9.5 Conclusions.- References.
利用场离子显微镜-原子探针,透射电镜及高分辨电镜研究了非晶合金Fe-7Zr-3B中α-Fe相的结晶过程,结果表明,α-Fe相是以形核-生长方式结晶的.在制备态非晶样品中观察到了中程有序畴,结晶前,中程有序畴得到进一步发展;在α-Fe相的形核生长阶段,观察到Zr原子在α-Fe相/非晶相的界面上富集,说明α-Fe晶粒的生长是由Zr原子的扩散所控制的.