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，布朗大学的王来生教授和他的学生正在使用复杂的激光光谱技术来研究硼和金属硼化物的团簇。正在研究的团簇是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。王的研究小组能够连续改变星团中的原子数量，这意味着他们可以详细地探索原子是如何相互结合的。硼团簇中的化学键非常强，这可能意味着这些团簇可能会使具有新的有用性质的新材料成为可能。王教授和他的研究团队对创建和表征新型的硼原子簇结构很感兴趣，其中包括含有一些金属原子的原子簇，如铋(Bi)、钴(Co)、铑(Rh)和铱(Ir)。除了实验工作中使用的激光，王的研究团队还进行理论计算，帮助解释实验数据并预测新的、前所未有的结构(例如，包含50个以上原子的团簇是什么样子的？)。该项目的长期目标是发现新的基于硼的分子和新形式的硼材料。该项目集中在三个子主题上：1)大尺寸选择的硼团簇的结构演变，2)中性硼团簇和硼球烯(笼状硼团簇)，以及3)金属掺杂的硼团簇。这些团簇是由激光蒸发超音速团体源产生的，并用各种实验和理论技术进行了研究。光电子能谱被用来探测40个以上带负电荷的大团簇的结构和成键。利用带负电荷的硼团簇的高分辨率光电子成像为相关的中性团簇提供振动和结构信息。作为高分辨率光电子成像实验的补充技术，红外和紫外双谐振法被用来直接探测中性硼团簇。用光电子能谱和高分辨光电子成象研究了金属掺杂的硼原子团簇的结构和成键。这些实验提供了振动和电子结构指纹，并结合计算化学来解释硼和金属掺杂的硼原子簇的结构、稳定性和化学键。这项工作的更广泛影响是为发现可能具有潜在技术应用和社会效益的新型硼基纳米材料奠定基础和知识基础。这个项目被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智力优势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.