Surface science of silicon dangling bonds, condensed molecular films and nanostructured materials

了解表面发生的化学过程对许多科学和技术领域至关重要，包括环境科学、材料研究、分子电子学和纳米技术。提出的工作旨在研究越来越复杂的衬底上的表面化学和物理，从单晶Si表面，到凝聚态多晶和非晶分子薄膜，再到纳米结构材料。我们的研究将集中在具有生物化学兴趣的吸附物上，并遵循它们的中间体在吸附和与热、低能电子和离子相互作用时的结构和电子性质的演变。利用脉冲激光沉积和分子束外延等专门工具，我们还将开发新型功能纳米材料，这不仅将为研究复杂表面的基本过程提供重要的测试平台，而且还将为开发新兴纳米技术领域的新应用提供基础平台。(1)涉及Si悬空键的有机硅表面化学：重点研究含多个官能团的有机酸的表面化学，有机半导体低聚物的演化，DNA核碱基的表面反应，以及低能电子/离子诱导的过程。(b)冰表面化学：简单氨基酸和DNA核碱基在冰上的吸附可能是原始世界生命形成的关键。研究导致冰上肽键形成的表面化学反应与温度的关系将会引起极大的兴趣。(c)纳米结构材料：新型金属核壳纳米粒子的发展为催化和电子学提供了许多最近的商业应用。磁性纳米粒子为磁场定向生长、自组装和在外加磁场中成图化提供了新的前景。制备半金属铁磁纳米薄膜（包括CrO2， Sr2FeMoO6， Fe3O4和金属掺杂ZnO）为自旋电子学，光伏和光子学提供了基本的材料平台。

Understanding the chemical processes occurring on surfaces is fundamentally important to many areas of science and technology including environmental science, materials research, molecular electronics and nanotechnology. The proposed work seeks to study the surface chemistry and physics on increasingly more complex substrates, from single-crystal Si surfaces, to condensed polycrystalline and amorphous molecular thin films, to nanostructured materials. Our study will focus on adsorbates with biochemical interest, and to follow the evolution of the structures and electronic properties of their intermediates upon adsorption and interactions with heat, low-energy electrons and ions. Using specialized tools such as pulsed laser deposition and molecular beam epitaxy, we will also develop new classes of functional nanomaterials, which would not only provide important test beds for investigating fundamental processes on complex surfaces, but also serve as basic platforms for developing new applications in the emerging field of nanotechnology. Three specific programs are proposed: (a) Organosilicon surface chemistry involving the Si dangling bonds: Special emphasis will be placed on studying the surface biochemistry of organic acids containing multiple functional groups, evolution of organic semiconductor oligomers, surface reactions of DNA nucleobase groups, and processes induced by low-energy electrons/ions. (b) Ice surface chemistry: Adsorption of simple amino acids and DNA nucleobase groups on ice may hold the key to life formation in the primordial world. Following the surface chemistry leading to the formation of peptide bonds on ice as a function of temperature would be of great interest. (c) Nanostructured materials: The development of novel metallic core-shell nanoparticles has provided much of the recent commercial applications in catalysis and electronics. Magnetic nanoparticles offer new prospects for field-directed growth, self-assembly and patterning in an external magnetic field. Fabricating half-metallic ferromagnetic nano-films (including CrO2, Sr2FeMoO6, Fe3O4, and metal-doped ZnO) provides the basic material platforms for spintronics, photovoltaics and photonics.