Nanoclusters of Boron and Borides

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。技术摘要包含几个到几百个原子的原子团簇表现出与大小相关的化学和物理性质，并构成了纳米科学的基础。在这项由NSF材料研究部（DMR）和化学部（CHE）支持的提案中，王博士和他的学生计划研究元素硼和金属硼化物的纳米团簇。他们的实验主要涉及由激光汽化簇源产生的大小选择簇阴离子的光电子能谱研究。光电子能谱包含团簇的电子结构指纹，它与理论计算相结合，提供有关团簇的结构、稳定性和化学键的信息。本研究的目的是阐明硼纳米团簇的结构转变与尺寸的关系，为硼纳米结构的新形式奠定基础。此外，提出了利用高分辨率光电子成像技术获取硼团簇的振动信息。本研究将系统地阐明硼团簇的结构和结构转变，为了解硼纳米管和类富勒烯纳米结构的生存能力和稳定性奠定基础。在聚类研究的指导下，还计划进行探索性综合。过渡金属二硼化物最近被研究作为超硬材料的候选材料。然而，在分子水平上对金属-硼化学键所知甚少。Wang博士和他的学生还计划通过结合光电子能谱和理论计算来研究小型双金属硼化物簇MxBy （M = Re, Os, Ir， Ru和Fe）的结构和键合。有关M-B键强度以及MxBy硼化物簇的稳定性和键合的信息，将对设计和理解超硬二硼化物材料有价值。原子团簇的基础研究导致了纳米科学和材料科学的重大进展，如富勒烯和碳纳米管。本研究项目的重点是硼和金属硼化物簇。在气相团簇中发现的新的分子结构和化学键的概念有望在化学、纳米科学和材料科学中产生广泛的影响。对硼团簇的研究可能会导致硼纳米管和硼富勒烯的发现，从而开辟新的研究方向。金属硼化物簇工作将有助于设计和发现新的超硬硼化物材料，具有广泛的工业应用前景。该研究项目将涉及重要的国内和国际合作，为从事研究的学生提供一个充满活力的学习环境。该研究项目也被整合到研究生和本科生的教学中，并通过新的研究方法为研究基础设施的发展做出贡献。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).TECHNICAL SUMMARYAtomic clusters containing a few to few hundred atoms exhibit dramatic size-dependent chemical and physical properties and form the foundation for nano-science. In this proposal, supported by both the Divisions of Materials Research (DMR) and Chemisty (CHE) at NSF, Dr. Wang and his students plan to investigate nanoclusters of elemental boron and metal borides. Their experiment involves primarily photoelectron spectroscopy studies of size-selected cluster anions, produced by a laser vaporization cluster source. Photoelectron spectra contain electronic structure fingerprints for the clusters, which are combined with theoretical calculations to provide information about the structure, stability, and chemical bonding of the clusters. The objective of the research is to elucidate the structural transitions of boron nanoclusters as a function of size and lay the foundation for new forms of boron nanostructures. In addition, high resolution photoelectron imaging is proposed for boron clusters to obtain vibrational information. The proposed research will systematically elucidate the structures and structural transitions of boron clusters to build the knowledge base for understanding the viability and stability of boron nanotubes and fullerenelike nanostructures. Guided by the cluster studies, exploratory synthesis is also planned. Transition metal diborides have been recently investigated as candidates for superhard materials. However, very little is known about the metal-boron chemical bond at the molecular level. Dr. Wang and his students also plan to study the structures and bonding of small bimetallic boride clusters, MxBy (M = Re, Os, Ir, Ru, and Fe), by combining photoelectron spectroscopy and theoretical calculations. Information about the M-B bond strengths, and the stability and bonding in the MxBy boride clusters, will be valuable to design and understand superhard diboride materials. NON-TECHNICAL SUMMARYFundamental studies of atomic clusters have led to major advances in nanoscience and materials science, such as the fullerenes and carbon nanotubes. The focus of this research program is on clusters of boron and metal borides. The new molecular structures and concepts of chemical bonding discovered in the gas-phase clusters are expected to have broad impact in chemistry, as well as in nanoscience and materials science. The proposed work on boron clusters may lead to discoveries of boron nanotubes and boron fullerenes, which may open up new directions of research. The metal boride cluster work will help the design and discovery of new superhard boride materials, which have wide industrial applications. The research program will involve significant national and international collaborations, providing a dynamic learning environment for students engaged in the research. The research program is also integrated to the teaching of both graduate and undergraduate students and contribute to the development of research infrastructure through new research methodologies.