Near-field coupling between molecular vibrations and plasmonic metal oxide nanocrystals

化学家可以培育极小的晶体。最小的晶体只有几纳米大小，大约比一张纸小10万倍。这些小晶体只包含几千个原子。一些纳米晶体可以聚光，聚光后的能量可以用于从太阳能转换到传感等各种应用。然而，单一类型的纳米晶体只能集中几种颜色的光。通过改变它的化学成分，人们可以为特定的应用调整这种颜色。在化学系大分子、超分子和纳米化学项目的支持下，德克萨斯大学奥斯汀分校的迪莉娅·米利伦教授正在培育能够集中红外光的纳米晶体。虽然我们看不见红外光，但我们感觉到它是来自阳光或热火的热量。密尔伦教授和她的学生一起研究纳米晶体的大小、形状和组成如何影响其聚焦红外光的能力。他们的发现可能会带来更好的检测特定化学物质的方法，并改进催化方法，这将对社会产生重要的好处。一个关于纳米科学和光物质相互作用的互动教育模块正在适应不同的受众，包括德克萨斯聋人学校的高中生和参观德克萨斯大学校园的女生节和探索德克萨斯大学的年轻学生，这两个都是面向社区的外展活动。本项目的目标是合成含有共价掺杂剂的胶体金属氧化物纳米晶体（NCs），这种掺杂剂可以诱导高浓度的自由电子，从而在中红外光谱区域产生局部表面等离子体共振（LSPR）。定量研究了LSPR模式与近端有机分子振动模式之间的耦合关系。大多数关于LSPR的研究都集中在贵金属上，为了达到中红外频率，贵金属必须被模式化成更大的微米级金属结构。这种方法的局限性激发了等离子体金属氧化物NCs的研究。这是定量地确定NC物理化学性质如何控制LSPR和振动模式之间耦合的性质和强度，最终导致开发敏感和化学特异性检测器所需的基础理解，并指导能量流以调整和增强催化过程。该团队正在创建交互式教育活动，以说明光与物质的相互作用如何在现代应用中使用，例如电子显示器和太阳能电池。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。

Chemists can grow extremely small crystals. The smallest crystals can be only a few nanometers in size, or about 100,000 times smaller than a sheet of paper. These small crystals contain just a few thousand atoms. Some nanocrystals can concentrate light and the focused energy can be used in applications ranging from solar energy conversion to sensing. However, a single type of nanocrystal can only concentrate a few colors of light. By changing its chemical composition, one can adjust this color for specific applications. With support from the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Professor Delia Milliron at the University of Texas at Austin is growing nanocrystals that concentrate infrared light. While we cannot see infrared light, we feel it as heat from sunlight or a hot fire. Working with her students, Professor Milliron is studying how the size, shape, and composition of a nanocrystal influences its ability to concentrate infrared light. Their discoveries could lead to better ways of detecting specific chemicals and improved catalytic methods, which would have important benefits to society. An interactive educational module regarding nanoscience and light-matter interactions is being adapted to reach diverse audiences, including high school students at Texas School for the Deaf and younger students who visit UT's campus for Girl Day and Explore UT, both are community-oriented outreach events.This project targets the synthetic development of colloidal metal oxide nanocrystals (NCs) containing aliovalent dopants that induce a high concentration of free electrons, leading to localized surface plasmon resonance (LSPR) in the mid-infrared spectral region. Coupling between LSPR modes and the vibrational modes of proximal organic molecules is studied quantitatively. Most research on LSPR has focused on noble metals, which must be patterned into larger, micron-scale metal structures to reach mid-infrared frequencies. The limitations of that approach motivate the investigation of plasmonic metal oxide NCs. This is quantitatively establishing how NC physiochemical properties control the nature and strength of coupling between LSPR and vibrational modes, ultimately leading to the foundational understanding needed to develop sensitive and chemically specific detectors, and to direct the flow of energy to tune and enhance catalytic processes. The team is creating interactive educational activities that illustrate how the interaction of light and matter is used in modern applications, such as electronic displays and solar cells.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.