异金属（亚）单层原子与基底相互作用的SPM研究

By employing electrochemical method and in-situ scanning tunneling microscopic technique, underpotential deposition(UPD) of practically important Sn and Sb on Au(hkl) and Cu(hkl) electrode surfaces are investigated systematically in terms of crystallographic misfit, ionic adsorption, surface reconstruction and surface alloying. Interesting features are observed such as 1)Size-confined clustering and anisotropic growth of Sn on Au(111) and Au(100) and their reconstructed surfaces; 2)Sb adlayer induced relaxation of Au(111) （?3′22）under electrochemical control; 3)Competitive adsorption and restricted underpotential deposition of Sn on Sulfate covered Cu(111);4)Surface alloying and its suppression by coadsorption of ions and adatoms;5)Directed growth of Sb nano-strips on Cu(100). These results demonstrate that subtle electronic and geometric differences of the substrate such as surface reconstruction may leads to significantly different UPD behaviors. The substrate structures also influence the degree of surface alloying: Surface alloying proceeds by site exchange on (111) surfaces, but by forming surface alloy complex which is restricted to the topmost layer of the surface; Surface reconstruction with an expanded top most-layer may even favor surface alloying via strain relief. On the other hand, strong adatoms-substrate also induces the relaxation of the surface structure; With sufficiently large ion-ion interaction, UPD is hindered with the breakthrough sites at the periphery of the ionic adlayer, and proceeds by displacing the ions and releasing the bare surface sites for further deposition. In addition, the UPD behavior affects the growth behavior of overpotential deposition. In all systems that have been carried out in the present work, the metal monolayers are observed to be much less than its geometric height, implying strong adatoms-substrate interactions..The observed novel UPD features are in contrast to some of previously reported systems and may provide a new insight into the dynamics of UPD and related fundamental process such as surface reconstruction, competitive adsorption and surface alloying. Furthermore, the size-confined clustering, the anisotropic growth and nano-strip formation may serve as a new class of methods for surface nanostructuring, which is important in probing nano-scale phenomena as well as possible applications.

以扫描探针显微技术（SPM）为主要研究手段，以表面科学中的重要现象—金属欠电位沉积║PD）为研究对象，发展有关研究方法，从UPD层的收缩现象和UPD的合金化现象二方面进行系统研究，从原子水平和电子结构层次探讨异金属（亚）单层原子与基底原子相互作用的本质。为控制（超）薄膜有序生长和制备高性能的表面材料提供理论和实验依据。