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。技术和技术包含几百到几百个原子的原子团簇表现出显著的大小相关的化学和物理性质，并构成纳米科学的基础。在这项由美国国家科学基金会材料研究部(DMR)和化学部(CHE)共同支持的计划中，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激光蒸发团簇光源产生的大小选定的团簇阴离子的光电子能谱研究。光电子光谱包含团簇的电子结构指纹，这些指纹与理论计算相结合，提供关于团簇的结构、稳定性和化学键的信息。这项研究的目的是阐明硼纳米团簇的结构转变随尺寸的变化，并为新形式的硼纳米结构奠定基础。此外，还提出了用高分辨率光电子成像来获取B团簇的振动信息。这项研究将系统地阐明硼原子簇的结构和结构转变，为理解硼纳米管和富勒烯类纳米结构的活性和稳定性奠定基础。在集群研究的指导下，还计划进行探索性合成。过渡金属二硼化物最近被作为超硬材料的候选材料进行了研究。然而，人们对分子水平上的金属-硼化学键知之甚少。王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双金属硼化物小团簇MxBy(M=Re、Os、Ir、Ru和Fe)的结构和成键。关于M-B键强度以及MxBy硼化物团簇的稳定性和成键的信息，对于设计和理解超硬二硼化物材料将是有价值的。对原子团簇的基础研究在纳米科学和材料科学方面取得了重大进展，例如富勒烯和碳纳米管。这项研究计划的重点是硼和金属硼化物的簇合物。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以及纳米科学和材料科学中产生广泛的影响。提出的关于硼团簇的工作可能会导致发现硼纳米管和硼富勒烯，这可能会开辟新的研究方向。金属硼化物团簇的工作将有助于设计和发现具有广泛工业应用的新型超硬硼化物材料。该研究计划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。该研究计划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促进研究基础设施的发展。

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.