Cooperative Action of Light and Surfactants in Plasmon-Driven Anisotropic Growth of Silver Nanostructures

金属纳米颗粒可以制成各种不同的形状。这些小粒子中的松散电子可以被光推动，像池子里的波浪一样晃动。随着光强度的增加，这些波（称为等离子激元）变得更大，有了足够的能量，它们可以引起化学反应。粒子的形状也会影响等离子体激元波的大小，粒子的角比粒子的其他部分产生更大的波。因此，需要具有尖锐特征的颗粒。创造这些复杂结构的一个策略是利用光来促进生长。问题是，这些尖锐特征形成的机制尚不清楚，因此难以控制。在化学系大分子、超分子和纳米化学（MSN）项目的支持下，佛罗里达大学的Wei教授正在探索棱镜形银纳米结构的光驱动生长。从该项目中获得的见解可能会产生新的材料，推动从癌症治疗到太阳能转换的各种技术的发展。该项目还为下一代科学家提供培训机会，并为高中生、教师和公众提供有关等离子体纳米材料的教育。魏教授还计划开发西班牙语的无线电模块，将普通科学带给佛罗里达州科学界历史上代表性不足的群体。魏教授与他的学生一起探索表面等离子体共振（SPR）在推动银纳米棱镜生长中的作用。这个过程从球形银纳米颗粒开始，然后将其暴露在强光源下。然后，研究小组使用透射电子显微镜（TEM）方法和电子能量损失光谱（EELS）观察粒子的生长，并用计算机模拟帮助解释实验数据。在单纳米粒子水平上的观察提供了调控等离子体驱动的银纳米棱镜合成的潜在光物理和化学过程的详细视图。该项目正在探索表面活性剂和金属SPR之间合作相互作用的重要性，以有效地利用等离子体驱动的光化学来合成纳米材料。在这个项目中获得的分子水平的见解不仅为设计和构建其他类型的形状控制等离子体纳米结构奠定了基础，更重要的是，它们的意义有益于等离子体光化学的更广泛领域，而不仅仅是纳米材料的合成。该奖项反映了美国国家科学基金会的法定使命，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。

Metallic nanoparticles can be created in a variety of different shapes. The loosely held electrons in these small particles, which can be pushed around by light, slosh around like waves in a pool. As the light intensity increases, these waves (called plasmons) become bigger, and with enough energy they can cause chemical reactions. The particle's shape can also affect the size of the plasmon waves, with corners creating bigger waves than other parts of the particle. As a result, particles with sharp features are desired. One strategy for creating these complicated structures is to use light to promote the growth. The problem is that the mechanism by which these sharp features form is not understood, and therefore difficult to control. With support from the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program in the Division of Chemistry, Professor Wei David Wei at the University of Florida is exploring the light-driven growth of Ag nanostructures with prismatic shapes. Insights gained from the project could lead to new materials, advancing technologies that range from cancer therapies to solar energy conversion. The project is also providing training opportunities for the next generation of scientists, as well as educating high school students, teachers, and the general public on plasmonic nanomaterials. Professor Wei also plans to develop radio modules in Spanish to bring general science to groups historically underrepresented in the scientific community in Florida. Working with his students, Professor Wei is exploring the role of the surface plasmon resonance (SPR) in driving the growth of Ag nanoprisms. The process starts with spherical Ag nanoparticles, which are then exposed to an intense light source. The team then watches the particle grow using transmission electron microscopy (TEM) methods and electron energy loss spectroscopy (EELS), and computer simulations aid in the interpretation of the experimental data. Observations at the single-nanoparticle level provide a detailed view of the underlying photophysical and chemical processes regulating the plasmon-driven synthesis of the Ag nanoprisms. The project is exploring the importance of a cooperative interplay between surfactants and metal SPR to effectively harness plasmon-driven photochemistry for nanomaterials synthesis. The molecular-level insights obtained in this project not only lay the groundwork for the design and construction of other types of shape-controlled plasmonic nanostructures, but more importantly, their implications benefit a broader field of plasmonic photochemistry beyond nanomaterials synthesis.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.