Topologically Enhanced Raman Spectroscopy

各种生化传感技术都是由生化分子与传感器材料之间的界面耦合作用决定的，其中传感器材料的表面电子态和表面原子端基起着关键作用。传统材料易受悬挂键、空位或掺杂引起的表面态的破坏。相比之下，拓扑量子材料，一类材料，如拓扑绝缘体和Weyl半金属，具有独特的拓扑保护表面态，对表面修改、形状缺陷和缺陷具有健壮性。因此，拓扑绝缘体和Weyl半金属构成了传感应用中连接生化分子的理想平台。该项目将探索拓扑绝缘体和Weyl半金属的纳米结构作为与分子相互作用的敏感和低噪声平台，并产生前所未有的用于分子传感的拉曼增强信号。该项目跨越了拓扑量子物理和分子传感这两个科学学科的传统界限，将通过促进新方法和新材料的发明，开辟一条生化传感技术的新途径。该项目的研究将广泛影响多个学科，包括物理化学、量子材料、生物分子工程和光学。研究成果还将成为本科生和研究生以及K-12学生，特别是代表不足的少数民族和女性的优秀教材。教育和推广活动将培养新一代的劳动力，以处理涉及量子科学、新材料、光学和生化工程的多学科任务。该项目将开创拓扑量子材料在化学和生物医学中的应用，开发基于纳米结构拓扑绝缘体和Weyl半金属的新平台和方法，以实现高性能的表面增强拉曼光谱传感。中心假设是，纳米拓扑绝缘体和Weyl半金属由于其独特的拓扑保护表面电子态，可以产生超强、超稳定的表面等离子体，并与分子进行有效的界面耦合。纳米拓扑绝缘体和Weyl半金属具有高导电性和类自由电子的表面态，因此具有强而低损耗的表面等离子体。表面电子态是拓扑保护的，不受表面缺陷和形状缺陷的影响，因此拉曼增强将是超稳定的和低噪声的。此外，拓扑表面态诱导分子间的有效电子转移，通过化学增强机制进一步增强拉曼信号。该项目将开发基于拓扑绝缘体和Weyl半金属的拉曼增强平台，利用等离子体增强和化学增强。通过在拉曼增强装置中分别集成电化学反应和拓扑材料的磁场调谐，还将开发出多模和可调谐的拉曼传感平台。作为该项目的一部分，该项目中提出的教育计划将导致新的课堂和实验室教学模式，激发学生的创造力，并培养研究型课堂。研究生和本科生将通过参与该项目接受研究培训。K-12的学生将参加外展活动和实验室之旅，这些活动将根据这项研究的结果制定。这一奖项反映了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。

Various biochemical sensing techniques are governed by the interface coupling between biochemical molecules and sensor materials, in which the surface electronic states and surface atomic termination of the sensor materials play a key role. Conventional materials suffer from easily destroyable surface states derived from dangling bonds, vacancies, or doping. In contrast, topological quantum materials, a class of materials such as topological insulators and Weyl semimetals, possess unique topologically protected surface states that are robust against surface modifications, shape imperfections, and defects. Therefore, topological insulators and Weyl semimetals constitute ideal platforms to interface biochemical molecules for sensing applications. This project will explore nanostructures of topological insulators and Weyl semimetals as sensitive and low-noise platforms to interact with molecules and to produce unprecedented Raman enhancement signals for molecule sensing. This project cuts across traditional boundaries of two scientific disciplines, topological quantum physics and molecule sensing, and will open a new avenue of biochemical sensing technologies by fostering the invention of new methods and materials. The research of this project will broadly impact multiple disciplines including physical chemistry, quantum materials, biomolecular engineering, and optics. The research outcome will also constitute excellent educational materials for undergraduate and graduate students, and K-12 students, especially under-represented minorities and females. The educational and outreach activities will prepare the new generations of workforce to handle multidisciplinary tasks involving quantum science, new materials, optics, and biochemical engineering.This project will pioneer the usage of topological quantum materials in chemistry and biomedicine, develop new platforms and methods based on nanostructured topological insulators and Weyl semimetals to enable high-performance surface enhanced Raman spectroscopy sensing. The central hypothesis is that nanostructured topological insulators and Weyl semimetals can generate ultra-strong and ultra-stable surface plasmons and efficient interface coupling with molecules due to their topologically protected surface electronic states, unique to conventional materials. Nanostructured topological insulators and Weyl semimetals have highly conductive and free electron-like surface states, thus possess strong and low-loss surface plasmons. The surface electronic states are topologically protected and immune to surface defects and shape imperfection; thus Raman enhancement will be ultra-stable and low-noise. In addition, the topological surface states induce effective electronic transfer with molecules, further boosting Raman signals through chemical enhancement mechanisms. This project will develop the Raman enhancement platforms based on topological insulators and Weyl semimetals utilizing both plasmonic enhancement and chemical enhancement. Multimodal and tunable Raman sensing platforms will also be developed by integrating the electrochemical reactions and magnetic tuning of topological materials, respectively, in the Raman enhancement device. As part of the project, the educational programs proposed in this project will lead to new classroom and laboratory instructional modes, stimulate student creativity, and foster research-like classes. Graduate and undergraduate students will receive research training by participating in this project. K-12 students will participate in the outreach activities and lab tours which will be developed from the outcome of this research.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.