BRIGE: Nanocrystal Probes for Tip-Enhanced Raman Spectroscopy

智力优势：纳米级金属尖端的行为像光学天线，促进散射光的近场放大，并且正在探索作为超灵敏振动光谱学的高分辨率扫描探针。为了从每个探头获得最高的信号增益，金属尖端必须设计成高度调节的尺寸和形状。目前的制造方法生产的尖端具有一系列纳米级特征，难以表征，并且在使用时遭受机械和热损伤。这个bridge项目的研究目标是通过将胶体金属纳米晶体组装在原子力显微镜尖端上来制造金属尖端。本提案将评估基于纳米晶体的尖端的光学响应作为纳米晶体形状，尺寸和组装几何形状的函数。纳米晶体组件将被设计用于实现特定的近场电磁特性，包括可调谐等离子激元激发波长，多个纳米晶体之间的电磁耦合以及最佳的倏逝场衰减长度。最后，该项目将寻求将这些纳米晶体组件与扫描探针仪器集成，并演示尖端增强拉曼光谱用于化学鉴定、检测和绘图等应用。更广泛的影响：拟议的研究将导致强大的、定制的、超灵敏的纳米级探针尖端的发展，用于尖端增强拉曼光谱和其他近场光学测量。一种能够将定量化学分析与超过衍射极限的空间分辨率相结合的光学技术，将在需要表面表征的广泛领域产生巨大影响，包括：化学传感和分子鉴定、多相催化、纳米结构表征、生物材料开发和基础生命科学研究。该研究项目将研究与指导、教育和社会推广相结合，将产生广泛的影响。这项提案的研究成果将在加州大学圣地亚哥分校的纳米工程课程中介绍给本科生，作为纳米工程基础研究如何推动技术创新的一个例子。将与以社区为基础的组织一起开展工作，促进大学前一级的纳米科学教育，特别注意通过纳入代表性不足的少数民族和妇女来扩大参与。此外，提议的努力包括开发在线维基，以便在纳米材料社区之外传播研究成果。这些不同的教育组成部分将被设计用于参与各级教育的工程师，鼓励他们与同龄人、导师和社区进行开放的科学讨论。

Intellectual Merit: Nanoscale metal tips behave like optical antenna to facilitate near-field amplification of scattered light and are being explored as high-resolution scanning probes for ultrasensitive vibrational spectroscopy. To obtain the highest signal gain from each probe, the metal tip must be designed with highly regulated size and shape. Current fabrication methods produce tips with a range of nanoscopic features that are difficult to characterize and suffer from both mechanical and thermal damage upon use. The research objective of this BRIGE project is to fabricate metal tips by assembling colloidal metal nanocrystals onto an atomic force microscope tip. This proposal will evaluate the optical response of nanocrystal-based tips as a function of nanocrystal shape, size, and assembly geometry. Nanocrystal assemblies will be engineered to achieve specific near-field electromagnetic properties, including tunable plasmon excitation wavelengths, electromagnetic coupling between multiple nanocrystals, and optimal evanescent field decay lengths. Finally, this project will seek to integrate these nanocrystal assemblies with scanning probe instrumentation and to demonstrate tip-enhanced Raman spectroscopy for applications such as chemical identification, detection, and mapping. Broader Impacts: The proposed research will lead to the development of robust, tailored, and ultrasensitive nanoscale probe tips for tip-enhanced Raman spectroscopy and other near-field optical measurements. An optical technique that is able to pair quantitative chemical analysis with spatial resolution beyond the diffraction limit would have a tremendous impact in a broad range of fields that require surface characterization, including: chemical sensing and molecular identification, heterogeneous catalysis, nanostructure characterization, biomaterials development, and basic life sciences research. This research project will make broad impacts by integrating research with mentoring, education, and social outreach. The research outcomes of this proposal will be introduced to undergraduates within the NanoEngineering curriculum at UC San Diego as an example of how basic research in nanoengineering can drive technological innovation. Work will be conducted with community-based organizations to promote nanoscience education at the precollege level, with particular attention given toward broadening participation through the inclusion of underrepresented minorities and women. In addition, the proposed efforts include the development of online wikis for the dissemination of research results beyond the nanomaterials community. These different educational components will be designed to engage engineers at all levels of education, encouraging open lines of scientific discussion with their peers, mentors, and community.