Probing the Electronic Structure and Chemical Bonding of Cryogenically-Cooled Boron and Metal-Boride Nanoclusters

在化学系化学结构、动力学和机理A(CSDM-A)项目的支持下，布朗大学的王来生教授和他的研究小组将使用高分辨率光电子成像和光电子能谱研究尺寸选定的硼和金属硼化物纳米团簇。与碳中的四个价电子相比，硼只有三个价电子，因此被认为是缺电子的。硼的电子缺乏导致了含硼分子中复杂的结构和独特的化学键，这是具有挑战性的研究。王教授和他的学生将使用自制的激光蒸发团簇光源产生硼和金属硼化物纳米团簇，并利用光电子能谱和成像结合理论计算来提供对它们的稳定性、结构和化学键的见解。他们的研究可能导致发现新型的基于硼和硼化物的纳米结构，并提供关于硼化学和化学键的基础知识。该项目的研究将融入物理化学教学，并将为本科生和研究生提供设计和建造先进的实验仪器和计算化学的培训机会。本项目重点研究了硼团簇的结构和成键，以期深入了解金属-硼键的性质和大的硼团簇的结构演变，为开发新型的硼基纳米材料奠定基础。为了实现这些研究目标，王来胜教授和他的学生们建造了两种不同类型的光电子能谱装置。一种装置包括磁瓶光电子分析器，目的是提供具有广泛光子能量的光电子谱。分辨良好的光电子光谱提供了电子指纹，这对于与理论计算进行比较以阐明尺寸选择的硼纳米团簇的结构和成键是至关重要的。第二种设备包括高分辨率光电子成像，目的是获得振动信息。正在开发一种低温冷却离子陷阱，以从激光汽化源产生冷硼团簇；这是获得硼和金属-硼化物团簇的振动分辨光电子光谱所必需的。该项目的更广泛影响包括发现具有作为纳米技术新平台的潜力的新型硼基纳米材料。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。

With support from the Chemical Structure, Dynamics, and Mechanisms A (CSDM-A) program in the Division of Chemistry, Professor Lai-Sheng Wang and his research group at Brown University will investigate size-selected boron and metal-boride nanoclusters using high-resolution photoelectron imaging and photoelectron spectroscopy. Boron has only three valence electrons compared to four in carbon and is thus considered to be electron deficient. The electron deficiency of boron results in complicated structures and unique chemical bonds in boron-containing molecules, which are challenging to investigate. Professor Wang and his students will generate boron and metal-boride nanoclusters using a home-built laser-vaporization cluster source and utilize photoelectron spectroscopy and imaging in conjunction with theoretical calculations to provide insights into their stabilities, structures, and chemical bonding. Their studies could lead to the discovery of novel boron- and boride-based nanostructures, as well as provide fundamental knowledge about boron chemistry and chemical bonding. The research in this project will be integrated into the teaching of physical chemistry, and will provide training opportunities for undergraduate and graduate students in the design and construction of advanced experimental instrumentation and computational chemistry. This project focuses on the structure and bonding of boron clusters to provide insight into the nature of the metal-boron bonds and structural evolution of large boron clusters to lay the foundation for new boron-based nanomaterials. To achieve these research goals, Professor Lai-Sheng Wang and his students have built two different types of apparatus for photoelectron spectroscopy. One apparatus involves a magnetic-bottle photoelectron analyzer and is aimed at providing photoelectron spectra with a wide range of photon energies. Well-resolved photoelectron spectra provide electronic fingerprints, which are crucial for comparison with theoretical calculations to elucidate the structures and bonding of size-selected boron nanoclusters. The second apparatus involves high-resolution photoelectron imaging, which is aimed at obtaining vibrational information. A cryogenically cooled ion trap is being developed to create cold boron clusters from the laser-vaporization source; this is needed to obtain vibrationally resolved photoelectron spectra for boron and metal-boride clusters. The broader impact of this project includes the discovery of novel boron-based nanomaterials with potential as new platforms for nanotechnology.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.