CAREER: Tuning optical responses in artificial molecules of monovalent gold nanocrystals

加州大学河滨分校的唐明（Ming L. Tang）在大分子、超分子和纳米化学项目的支持下，以独特的定义明确的方式将纳米颗粒连接在一起，获得了CAREER奖。由金和其他贵金属制成的纳米粒子可以表现出表面等离子体模式，这种模式在吸收或散射可见光谱特定区域的光方面特别有效。这项研究是将它们以选择性的方式连接在一起，目标是扩大我们在纳米级控制光与物质相互作用的能力。该方法是通过化学手段，因此人们可以很容易地扩大这些组装的合成规模。这个CAREER项目的教育部分是向更多的公众传递等离子体纳米粒子迷人特性的兴奋。它包括为一年级本科生开设以纳米材料为重点、以发现为基础的实验课程“用等离子体和聚合物绘画”。这是加州大学河滨分校（UCR）学习社区项目的新成员，该项目已被证明可以提高STEM专业的保留率，并将四年制毕业率从24%提高到40%。该课程的第一年学生领袖将与当地的中学生和高中生一起进行科学演示，并以他们个人获得STEM学位的故事来激励他们。PI指导这些学校的学生和教师，为他们提供在她的研究实验室与研究生和本科生一起工作的机会。控制纳米粒子组件中纳米级光-物质相互作用的目标是通过诱导强电和强磁跃迁来实现的，特别是后者，在可见频率下特别弱。超分子化学和固相合成技术正被用于制造“单价金”构建块，即，每个金纳米颗粒都有一个单一的结合位点，作为目前基于dna的自组装技术的强大替代品。自组装方法旨在控制5-100纳米大小的粒子，并将粒子间距离控制在1-20纳米量级。首先，精确控制两个不同组成的纳米粒子之间的距离，产生异源二聚体，用于识别对称性论点所不允许的模式。其次，由于分子支架所决定的粒子间几何结构，电偶极子和磁偶极子都在人工分子内的循环电流中被诱导。强，可调谐磁偶极子允许引入范诺共振与高质量的因素是有用的传感。第三，三维四面体结构的核壳纳米粒子预计具有重叠的电偶极子和磁偶极子正在研究中。

Ming L. Tang of the University of California Riverside is supported by the Macromolecular, Supramolecular and Nanochemistry program in a CAREER award to link nanoparticles together in uniquely well-defined ways. Nanoparticles made of gold and other noble metals can exhibit surface plasmon modes that are particularly effective at absorbing or scattering light in specific regions of the visible spectrum. This research is to hook them together in selective ways, the goal being to expand our ability to control interactions of light with matter at the nanoscale level. The approach is by chemical means, so that one can readily scale up the synthesis of these assemblies. The education component of this CAREER project is to deliver to the greater public the excitement of the fascinating properties of plasmonic nanoparticles. It includes the creation of a nanomaterials-focused, discovery-based laboratory course, "Painting with Plasmons and Polymers," for first year undergraduate students. This represents a new addition to the University of California Riverside's (UCR's) Learning Community program, which has been shown to increase retention rates of STEM majors and push 4-year graduation rates from 24% to 40%. First year student leaders from this class are expected to engage local middle and high school students with scientific demonstrations and to inspire them with stories about their personal path towards a STEM degree. The PI mentors students and teachers from these schools by providing them an opportunity to work in her research laboratory along with graduate students and undergraduates.The goal of controlling nanoscale light-matter interactions in nanoparticle assemblies is achieved by inducing strong electric and magnetic transitions, particularly the latter, which are especially weak in the visible frequencies. Supra-molecular chemistry and solid phase synthesis is being used to create "monovalent gold" building blocks, i.e., gold nanoparticles each with a single binding site, as a powerful alternative to the current state of the art DNA-based self-assembly. The self-assembly method aims to control particles from 5-100 nm in size and to engineer inter-particle distances on the order of 1-20 nm. First, precise control over the distance between two nanoparticles of different composition creates heterodimers employed to identify modes disallowed by symmetry arguments. Second, by virtue of an inter-particle geometry dictated by a molecular scaffold, both electric and magnetic dipoles are induced in the circulating currents within the artificial molecule. Strong, tunable magnetic dipoles allow introduction of Fano resonances with high quality factors that are useful for sensing. And third, 3-D tetrahedral constructs with core-shell nanoparticles predicted to have overlapping electric and magnetic dipoles are being investigated.