Surface Chemical Effects On Localized Surface Plasmon Resonance In Metal Oxide Nanocrystals

在化学系大分子、超分子和纳米化学项目（MSN）的支持下，德克萨斯大学奥斯汀分校的Delia Milliron教授将表面化学反应与先进的化学分析相结合，研究金属氧化物纳米晶体的光学和电子特性是如何受到其表面化学的影响的。在这些微小的晶体中，高度移动的电子在光的影响下移动，利用能量并将分散的红外光集中到单个分子大小的局部区域。然而，晶体非常小的尺寸意味着它们的表面对它们的移动电子和光的相互作用有很大的影响。millron教授和她的学生正在利用化学反应来改变纳米晶体表面的性质，以了解和控制表面化学的影响。他们的发现可能会改善光电子设备，如太阳能电池和显示器，以及更灵敏的化学传感器，以检测毒素或疾病的生化指标。该团队正在使用虚拟推广策略，特别是针对年轻受众，以扩大公众对科学的认识，并使科学更容易获得。本项目涉及掺杂金属氧化物纳米晶体的合成后表面化学修饰。在胶体合成过程中，在纳米晶体中加入了共价掺杂剂，引入了高浓度的自由电子，并导致红外光谱区域的局部表面等离子体共振（LSPR）。它们的局域表面等离子体共振（LSPR）吸收光谱和电磁场强度的近场增强受到引起能带弯曲的表面电子态存在的强烈影响。本项目采用合成后的表面化学反应来修饰纳米晶体表面的电子结构。偶极有机分子附着在表面以改变能级并修饰耗尽层。在胶体原子层沉积的绝缘金属氧化物壳的过度生长过程中，与负责带带的化学基团的反应会改变相关表面态的能级。光学分析将结合光发射光谱来分析表面化学影响LSPR的机制，目的是建立开发敏感和化学特异性探测器所需的基础认识，并指导能量流以调整和增强催化过程。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。

With support from the Macromolecular, Supramolecular and Nanochemistry Program (MSN) in the Division of Chemistry, Professor Delia Milliron of the University of Texas at Austin is combining surface chemical reactions and advanced chemical analysis to study how the optical and electronic properties of metal oxide nanocrystals are influenced by their surface chemistry. In these tiny crystals, highly mobile electrons move under the influence of light, harnessing energy and concentrating otherwise diffuse infrared light into local regions the size of individual molecules. However, the very small size of the crystals means that their surfaces have a big impact on their mobile electrons and their interaction with light. Professor Milliron and her students are using chemical reactions to change the properties of the nanocrystal surfaces to understand and control the influence of surface chemistry. Their discoveries could lead to improved optoelectronic devices, like solar cells and displays, and to more sensitive chemical sensors to detect toxins or biochemical indicators of disease. The team is using virtual outreach strategies, especially targeting younger audiences, to broaden public awareness of science and to make science more accessible.This project involves the post-synthetic surface chemical modification of doped metal oxide nanocrystals. Aliovalent dopants are incorporated in the nanocrystals during colloidal synthesis, introducing a high concentration of free electrons and leading to localized surface plasmon resonance (LSPR) in the infrared spectral region. Their localized surface plasmon resonance (LSPR) absorption spectra and the near-field enhancement of electromagnetic field intensity are strongly influenced by the presence of surface electronic states that induce band bending. This project employs post-synthetic surface chemical reactions to modify the electronic structure of the nanocrystal surfaces. Dipolar organic molecules are attached to the surface to shift the energy levels and modify the depletion layer. During overgrowth of insulating metal oxide shells by colloidal atomic layer deposition, reactions with the chemical groups responsible for band banding shift the energy levels of the associated surface states. Optical analysis will be combined with photoemission spectroscopy to analyze the mechanisms by which surface chemistry influences LSPR, with the aim of establishing the foundational understanding needed to develop sensitive and chemically specific detectors, and to direct the flow of energy to tune and enhance catalytic processes.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.