Collaborative Research: Excited State Dynamics of Structurally Precise Metal Nanoclusters

这些奖项由化学部的大分子/超分子/纳米化学项目授予克莉丝汀·艾肯斯（堪萨斯州立大学）、肯·纳彭伯格（佛罗里达州立大学）和克里斯·埃克森（科罗拉多州立大学），他们开发了预测尺寸为十亿分之一米（即，纳米颗粒）与光相互作用。从长远来看，这种金属纳米颗粒可能成为太阳能-电能转换设备、光学传感器、医疗诊断和治疗等领域的功能组件。目前，缺乏了解光如何激发能量流经这些材料限制了它们的应用。该合作团队将尖端的理论和实验光谱学沿着与精确的纳米颗粒合成和表征相结合。他们通过开发研究生培训课程来促进他们的多学科研究项目，这些课程专注于结构精确的光子纳米粒子的建模，测量和制备。该团队还积极参与K-12学生和教育工作者的外联活动;积极参与将研究纳入各自大学的本科课程;，并致力于让代表性不足的学生参与科学研究和教育。这一努力的主要目标是确定电子能量弛豫如何影响结构精确的金属纳米颗粒的纳米光子性质在1- 2nm尺寸域中。这项研究的特点是新兴的一类纳米光子材料：单层保护簇（MPC），它可以以原子精度合成和分离。这些材料代表了介于块状金属材料和较小的光激发分子之间的中间类材料。 该研究计划为所涉及的基本过程提供了纳米粒子特定的描述，例如电子-声子耦合，这对于确定纳米光子材料的功能特性至关重要。研究了MPC结构参数与电子弛豫之间的相互作用。具体目标是：1）确定电子-声子和电子-振动耦合的机制以及它们对Au 25（SR）18 MPC的电子弛豫动力学的影响，其中SR是烷醇; 2）理解金属掺杂对MPC动力学的影响; 3）描述电子-声子耦合如何随着MPC尺寸的增加而变化;以及4）研究MPC配体能带结构对电子动力学的影响。

These awards by the Macromolecular/Supramolecular/Nanochemistry Program in the Division of Chemistry to Christine Aikens (Kansas State University), Ken Knappenberger (Florida State University), and Chris Ackerson (Colorado State University) develop the ability to predict how metal particles with dimensions on the order of one-billionth of a meter (i.e., nanoparticles) interact with light. Such metal nanoparticles may, in the long term, become functional components in solar-to-electric energy conversion devices, optical sensors, and medical diagnostics and therapeutics, among others. Currently, the lack of understanding how light provokes energy flow through these materials limits their applications. The collaborative team combines cutting-edge theoretical and experimental spectroscopy along with precision nanoparticle synthesis and characterization. They facilitate their multi-disciplinary research project by developing graduate student training courses focused on modeling, measurement, and preparation of structurally precise photonic nanoparticles. The team is also strongly engaged in outreach to K-12 students and educators; is actively involved in incorporating research into the undergraduate curricula at each of their respective universitie;, and is committed to the involvement of underrepresented students in scientific research and education.The primary thrusts of this effort are to determine how electronic energy relaxation affects the nanophotonic properties of structurally precise metal nanoparticles in the 1-2 nm size domain. The research features an emergent class of nanophotonic materials: monolayer-protected clusters (MPCs), which can be synthesized and isolated with atomic precision. These materials represent an intermediate class of materials between bulk metallic materials and smaller photo-excited molecules. The program of study provides nanoparticle-specific descriptions for fundamental processes involved such as electron-phonon coupling, which are critical for determining the functional properties of nanophotonic materials. The research investigates the interplay between MPC structural parameters and electronic relaxation. The specific objectives are: 1) to determine the mechanisms of electron-phonon and electron-vibrational coupling and their influence on the electronic relaxation dynamics of Au25(SR)18 MPCs, where SR is an alkanethiol; 2) to understand the effects of metal doping on MPC dynamics; 3) to describe how electron-phonon coupling changes with increasing MPC dimensions; and 4) to investigate the influence of MPC ligand band structure on electron dynamics.