Infrared Chiral Plasmons for Vibrational Circular Dichroism Spectroscopy

在化学系化学测量和成像项目的支持下，犹他州大学的Jennifer Shumaker-Parry教授和她的团队正在努力提高测量分子“手性”（手性）的能力。 当一个分子和它的镜像不能重叠时，手性就产生了。 手性在自然界和医学中至关重要-例如，通常药物的一种分子形式是有效的，而其镜像是无效的甚至有毒的。 Shumaker-Parry小组正在努力提高一种称为振动圆二色性（VCD）的手性敏感方法的实用性，该方法利用某些金属纳米结构的能力来选择性地增强手性分子对偏振红外光的吸收。 该研究融合了材料科学，物理学，表面化学和工程学的元素，从而为研究生和本科生提供了极好的跨学科培训机会，他们共同研究纳米纤维，材料表征，光学研究，模拟和计算。教授Shumaker-Parry和她的学生组织和参与科学教育和推广计划在校园和社区，以鼓励学生参与科学。Shumaker-Parry教授和她的小组正在研究等离子体纳米结构与可调红外（IR）等离子体和等离子体增强VCD光谱的方向依赖手性光学活性。VCD结合了红外光谱和圆二色性（CD），提供有关化学基团和局部环境的信息，从而能够对小分子、生物分子和高阶组装体进行基于手性的结构分析。 同时具有可调红外等离子体和手性光学行为的纳米结构构成了系统研究手性分子VCD光谱中局部电场和磁场影响的基础。通过使用结构和取向的控制来操纵等离子体纳米结构的手征光学行为，产生对称和不对称的局部电场和磁场。这些雕刻的本地化领域对手性分子的影响将通过IR和VCD光谱来探测，因为手性行为是打开和关闭的，以及更精细的操纵。这些研究的目的是提供一个了解如何纳米结构与红外等离子体和手性光学活性的影响分子振动光谱的手性分子的VCD光谱。这些研究结果将为等离子体增强VCD分析手性分子奠定基础。手性分子的增强检测将降低痕量杂质的检测限，并可能导致对不对称催化产物的高灵敏度实时监测。该奖项反映了NSF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 Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Jennifer Shumaker-Parry and her group at the University of Utah are working to improve capabilities for measuring the "handedness" (chirality) of molecules. Chirality arises when a molecule and its mirror image are not superimposable. Chirality is critically important in nature and medicine - for example, it is common for one molecular form of a drug to be effective while its mirror image is ineffective or even toxic. The Shumaker-Parry group is striving to enhance the utility of a chirality-sensitive method known as Vibrational Circular Dichroism (VCD) by utilizing the ability of certain metal nanostructures to selectively enhance the absorption of polarized infrared light by chiral molecules. The research incorporates elements of materials science, physics, surface chemistry, and engineering, thereby providing excellent interdisciplinary training opportunities for graduate and undergraduate students who work together on nanofabrication, materials characterization, optical studies, simulations, and calculations. Professor Shumaker-Parry and her students organize and participate in science education and outreach programs on campus and in the community to encourage students to participate in science. These hands-on nanoscience activities provide excellent opportunities for graduate and undergraduate students to mentor participants and learn to communicate their research to a broad audience.Professor Shumaker-Parry and her group are studying plasmonic nanostructures with tunable infrared (IR) plasmons and orientation-dependent chiroptical activity for plasmon-enhanced VCD spectroscopy. VCD combines IR spectroscopy and circular dichroism (CD) to provide information about chemical groups and local environment enabling chiral-based structural analysis of small molecules, biological molecules, and higher order assemblies. Nanostructures with both tunable IR plasmons and chiroptical behavior form the foundation of systematic studies of the impact of local electric and magnetic fields in VCD spectroscopy of chiral molecules. By manipulating chiroptical behavior of plasmonic nanostructures using control of structure and orientation, symmetric and asymmetric localized electric and magnetic fields are produced. The influence of these sculpted localized fields on chiral molecules will be probed through the IR and VCD spectra as the chiroptical behavior is turned on and off, as well as more finely manipulated. The studies aim to provide an understanding of how nanostructures with IR plasmonic and chiroptical activity impact molecular vibrational spectra of chiral molecules in VCD spectroscopy. The findings from these investigations will establish a foundation for plasmon-enhanced VCD for analysis of chiral molecules. Enhanced detection of chiral molecules would lower detection limits for trace impurities and could lead to highly sensitive real-time monitoring of products in asymmetric catalysis.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.