Investigation of Boron and Boride Nanoclusters: Laying the Foundation for New Boron Nanostructures and Nanomaterials

在这个由化学系化学结构、动力学和机理（CSDM-A）项目资助的项目中，布朗大学的王来胜教授和他的学生们正在使用先进的激光光谱技术来研究硼和金属硼化物的团簇。所研究的团簇是3-40个原子的聚集体。 这些团簇的化学和物理性质取决于它们的大小。 Wang研究小组能够连续改变团簇中原子的数量，这意味着他们可以详细探索原子如何相互结合。 硼簇中的化学键非常强，这可能意味着这些簇可能使新材料具有新的和有用的特性。Wang教授和他的研究团队对创造和表征新型硼簇结构感兴趣，包括含有一些金属原子的簇，如铋（Bi），钴（Co），铑（Rh）和铱（Ir）。 除了实验工作中使用的激光器外，Wang研究团队还进行理论计算，帮助解释实验数据并预测新的、以前从未见过的结构（例如，包含50个以上原子的簇是什么样子的？）。该项目的长期目标是发现新的硼基分子和新形式的硼材料，重点研究三个子课题：1）大尺寸硼团簇的结构演化; 2）中性硼团簇和硼球烯（笼状硼团簇）; 3）金属掺杂硼团簇。这些团簇是由激光蒸发超音速团簇源产生的，并通过各种实验和理论技术进行了研究。光电子能谱被用来探测大于40个原子的大的带负电荷的硼团簇的结构和成键。高分辨率光电子成像的负电荷的硼团簇，以提供相关的中性团簇的振动和结构信息。作为高分辨光电子成像实验的补充技术，本文采用红外和紫外双共振方法直接探测中性硼团簇。利用光电子能谱和高分辨光电子像研究了金属掺杂硼团簇的结构和成键。这些实验提供了振动和电子结构指纹，结合计算化学来阐明硼和金属掺杂硼簇的结构，稳定性和化学键合。这项工作的更广泛影响是建立基础和知识库，以发现新的硼基纳米材料，这可能具有潜在的技术应用和社会效益。该项目由PI整合到物理化学教学中，并为研究生和本科生提供研究培训机会。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

In this project funded by the Chemical Structure, Dynamics and Mechanism (CSDM-A) program of the Chemistry Division, Professor Lai-Sheng Wang of Brown University and his students are using sophisticated laser spectroscopy techniques to study clusters of boron and metal borides. The clusters being studied are aggregates of 3-40 atoms. The chemical and physical properties of these clusters depend on their size. The Wang research group is able to continuously vary the number of atoms in a cluster, which means that they can explore in detail how the atoms are bonded to each other. The chemical bonds in boron clusters are very strong, which might mean that these clusters may make possible new materials with new and useful properties. Prof. Wang and his research team are interested in creating and characterizing novel boron cluster structures including clusters containing a few metal atoms such as bismuth (Bi) cobalt (Co), rhodium (Rh), and iridium (Ir). In addition to the lasers used in the experimental work, the Wang research team also do theoretical calculations that help interpret experimental data and predict new, never before seen structures (for example, what to clusters containing more than 50 atoms look like?). The long-term goal of the project is to discover new boron-based molecules and new forms of boron materials.The project focuses on three sub-topics: 1) structural evolution of large size-selected boron clusters, 2) neutral boron clusters and borospherenes (cage-like boron clusters), and 3) metal-doped boron clusters. These clusters are produced by a laser-vaporization supersonic cluster source and studied by a variety of experimental and theoretical techniques. Photoelectron spectroscopy is used to probe the structures and bonding of large negatively-charged boron clusters with more than 40 atoms. High-resolution photoelectron imaging of negatively-charged boron clusters is employed to provide vibrational and structural information for the associated neutral clusters. An infrared and ultraviolet double-resonant approach is used to directly probe neutral boron clusters, as a complementary technique to the high-resolution photoelectron imaging experiment. The structures and bonding of metal-doped boron clusters are studied by both photoelectron spectroscopy and high-resolution photoelectron imaging. These experiments provide vibrational and electronic structure fingerprints, which are combined with computational chemistry to elucidate the structure, stability, and chemical bonding of boron and metal-doped boron clusters. The broader impact of this work is to build the foundation and knowledge base to discover new boron-based nanomaterials, which can have potential technological applications and societal benefits. This project is integrated to the teaching of physical chemistry by the PI, as well as providing research-training opportunities for graduate and undergraduate students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.