Nanochemistry of sp3 Quantum Defects

碳纳米管是一种细小的管，其壁厚只有一个原子，直径可以比一根头发丝小十万倍。在完美的纳米管中，每个碳原子与其他3个原子结合，形成六边形晶格。缺陷可以通过将小的有机分子附着到管的外部来引入晶格中，使得晶格中的一些原子与4个碳原子结合，而不是3个。 这些量子缺陷吸引电荷载流子沿管沿着移动，使它们发出明亮的荧光。 在化学系大分子、超分子和纳米化学项目的支持下，马里兰州大学帕克分校的王宇煌教授和他的学生正在使用超分辨率显微镜技术研究单个荧光缺陷。 他们的发现可能对化学传感和量子信息科学的新兴技术产生重要影响。了解量子缺陷的纳米化学可以精确合成一个全新的量子发射体家族，并使实验探测单个缺陷极限的缺陷以及难以捕获的化学事件成为可能。这项研究有可能在纳米化学，量子物理学，量子理论，材料工程，光电子学，生物成像和量子科学与工程领域扩展应用，为美国提供更高的全球和经济竞争力。这项研究提供了一个独特的机会，以发展参与外展演示，并涉及来自代表性不足的群体在尖端研究的本科生。王教授和他的学生通过将选定的烷基或芳基官能团共价连接到半导体碳纳米管模型系统来设计和合成sp3量子缺陷。激子--电子-空穴对，每个都携带一个量子的激发能--被缺陷有效地收集，产生明亮的发射，在缺陷部位编码化学信息。该团队正在利用这一有趣的特性，并在短波红外线中推进超分辨率高光谱成像技术，以研究这些合成缺陷在单一缺陷极限下的光谱特性。此外，发射光谱对化学缺陷性质的依赖性被用来观察涉及氨基芳基取代基的模型化学反应中键的断裂和形成。 该团队还在表征高密度极限下sp3量子缺陷的功能化模式，并研究sp3缺陷化学如何在低维碳材料的sp2晶格上传播。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。

Carbon nanotubes are small tubes with walls that are a single atom thick and diameters that can be a hundred thousand times smaller than a strand of hair. In a perfect nanotube, each carbon atom is bound to 3 other atoms, forming a hexagonal lattice. Defects can be introduced in the lattice by attaching small organic molecules to the outside of the tube such that a few atoms in the lattice are bound to 4 carbons, instead of 3. These quantum defects attract charge carriers moving along the tube, enabling them to fluoresce brightly. With support from the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor YuHuang Wang at the University of Maryland College Park and his students are using super-resolution microscopy techniques to study individual fluorescent defects. Their discoveries could have important implications for emerging technologies in chemical sensing and quantum information science. Understanding the nanochemistry of quantum defects may enable the precise synthesis of a whole new family of quantum emitters, and make it possible to experimentally probe defects at the single defect limit as well as chemical events that are otherwise difficult to capture. This research has potential for extending applications in nanochemistry, photophysics, quantum theory, materials engineering, optoelectronics, biological imaging, and quantum science and engineering offering increased global and economic competitiveness for the United States. The research provides a unique opportunity to develop engaging outreach demos and involve undergraduate students from under-represented groups in cutting-edge research. Professor Wang and his students design and synthesize sp3 quantum defects by covalently attaching selected alkyl or aryl functional groups to semiconducting carbon nanotube model systems. Excitons -- electron-hole pairs each carrying a quantum of excitation energy -- are efficiently harvested by the defects producing bright emission that encodes chemical information at the defect site. The team is exploiting this intriguing property and advancing a super-resolution hyperspectral imaging technique in the shortwave infrared to study the spectroscopic properties of these synthetic defects at the single defect limit. Furthermore, the dependence of the emission spectrum on the nature of the chemical defect is being used to watch the breaking and formation of bonds in model chemical reactions involving aminoaryl substituents. The team is also characterizing functionalization patterns of sp3 quantum defects at the high-density limit and studying how sp3 defect chemistry may propagate on the sp2 lattice of low-dimensional carbon materials.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.