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

了解表面发生的化学过程对于环境科学、材料研究、分子电子学和纳米技术等许多科学和技术领域都是至关重要的。这项拟议的工作旨在研究越来越复杂的衬底上的表面化学和物理，从单晶硅表面，到凝聚的多晶和非晶态分子薄膜，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，并跟踪其中间体在吸附以及与热、低能电子和离子相互作用时的结构和电子性质的演变。我们还将利用脉冲激光沉积和分子束外延等专门工具，开发新型功能纳米材料，这些材料不仅将为研究复杂表面的基本过程提供重要的试验台，而且还将成为在新兴纳米技术领域开发新应用的基础平台。提出了三个具体的计划：(A)涉及硅悬键的有机硅表面化学：重点是研究含有多个官能团的有机酸的表面生物化学，有机半导体低聚物的演变，DNA碱基的表面反应，以及低能电子/离子诱导的过程。(B)冰面化学：简单氨基酸和DNA碱基团在冰上的吸附可能是原始世界生命形成的关键。随着温度的变化，在冰上形成多肽键的表面化学过程将引起人们极大的兴趣。(C)纳米结构材料：新型金属核壳纳米粒子的开发提供了许多最近在催化和电子方面的商业应用。磁性纳米颗粒为在外加磁场中的场定向生长、自组装和图案化提供了新的前景。制备半金属铁磁纳米薄膜(包括CrO2、Sr2FeMoO6、Fe3O4和金属掺杂的氧化锌)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.