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

在化学系大分子、超分子和纳米化学计划(MSN)的支持下，德克萨斯大学奥斯汀分校的Delia Milliron教授正在将表面化学反应和先进的化学分析相结合，研究金属氧化物纳米晶体的表面化学如何影响其光学和电子性质。在这些微小的晶体中，高度可移动的电子在光的影响下运动，利用能量并将原本漫射的红外光集中到单个分子大小的局部区域。然而，晶体的尺寸非常小，这意味着它们的表面对它们的移动电子和它们与光的相互作用有很大的影响。Milliron教授和她的学生正在使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进光电子设备，如太阳能电池和显示器，并产生更灵敏的化学传感器来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，以扩大公众的科学意识，使科学更容易获得。该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，异价掺杂被引入到纳米晶体中，引入了高浓度的自由电子，导致了红外光谱区的局域表面等离子体共振(LSPR)。它们的局域表面等离子体共振(LSPR)吸收光谱和近场电磁场强度的增强受表面电子态的影响很大，表面电子态的存在会引起能带弯曲。该项目利用合成后的表面化学反应来改变纳米晶体表面的电子结构。偶极有机分子附着在表面上，以改变能级和修饰耗尽层。在胶体原子层沉积金属氧化物绝缘壳层的过度生长过程中，与负责带带的化学基团的反应改变了相关表面态的能级。光学分析将与光电子能谱相结合，以分析表面化学影响LSPR的机制，目的是建立开发灵敏和化学特定的探测器所需的基础性理解，并引导能量流动来调整和增强催化过程。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.