Chemical Applications of Floquet State Spectroscopy

在化学系化学测量和成像（CMI）项目的支持下，威斯康星州大学的John Wright教授和他的研究小组正在开发一种名为Floquet状态光谱的新技术。Floquet态光谱学是核磁共振（NMR）光谱学的完全相干光学模拟。核磁共振光谱学利用无线电波与原子和分子相互作用，由于其能够表征复杂样品，因此在科学和技术中得到广泛应用。Floquet态光谱学承诺使用光而不是无线电波与分子相互作用的类似能力。该项目的目标是将Floquet态光谱应用于一系列化学系统，这些系统在化学的实际应用中非常重要。例如，Wright教授和他的团队使用该技术来确定分子内的原子必须如何弯曲、扭曲和拉伸，以改变将分子结合在一起的键。这些信息构成了合成化学的核心，因为它确定了反应的机制。该团队还与来自学术，工业和政府实验室的合作者合作，展示Floquet状态光谱用于表征复杂材料的独特能力，并展示该技术如何应用于许多科学和技术领域。该项目的广泛影响包括广泛传播这项新技术，学生培训机会，以及与斯佩尔曼学院的合作，使少数民族学生参与Floquet态光谱的夏季研究项目。Floquet态光谱测量基于同时驱动的多个振动和电子分子状态的系统的响应。由此产生的量子力学纠缠叠加态根据Floquet态的波矢组合发光。在分子的共振上扫描驱动频率导致输出光束的倍增增强，从而提供了一种测量多维光谱的方法。该研究项目的主要重点是使用Floquet态光谱来探测化学反应的机制。创建一个Floquet状态，它包含与混沌热运动驱动的振动和电子状态相同的振动和电子状态，可以直接观察和控制反应。钴胺素和钌-钌金属络合物是两种模型化合物，该团队正在使用它们来测试Floquet态光谱探测反应机制的能力。在钴胺素中，挑战在于了解与底物结合后C-Co键的断裂速率发生12个数量级变化的因素。在钌络合物中，挑战在于理解C-H键胺化的机制。该技术的传播包括与合作者合作，将Floquet态光谱应用于复杂聚合物材料的表征，在玻璃中处理锕系元素核废料，飞秒激发的光化学反应拉曼研究，以及胰腺癌医学诊断的发展。其他更广泛的影响包括对研究生的高级培训以及通过与斯佩尔曼学院的合作扩大参与的努力。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 (CMI) Program in the Division of Chemistry, Professor John Wright and his research group at the University of Wisconsin are developing a new technique called Floquet state spectroscopy. Floquet state spectroscopy is the fully coherent optical analogue of nuclear magnetic resonance (NMR) spectroscopy. NMR spectroscopy, which uses radio waves to interact with atoms and molecules, is used extensively in science and technology because of its ability to characterize complex samples. Floquet state spectroscopy promises similar capabilities using light, rather than radio waves, to interact with molecules. The goal of this project is to apply Floquet state spectroscopy to a range of chemical systems that are important in practical applications of chemistry. For example, Professor Wright and his team use the technique to determine how the atoms within a molecule must bend, twist, and stretch in order to change the bonds that hold the molecule together. This information forms the heart of synthetic chemistry because it identifies the mechanisms responsible for a reaction. The team also works with collaborators from academic, industrial, and government laboratories to demonstrate the unique capabilities of Floquet state spectroscopy for characterizing complex materials and to show how the technique can be applied in many fields of science and technology. The broader impacts of the project include wide dissemination of this new technology, student training opportunities, and a collaboration with Spelman College that engages minority students in summer research projects on Floquet state spectroscopy.Floquet state spectroscopy measures the response of a system based on simultaneously driven multiple vibrational and electronic molecular states. The resulting quantum mechanically entangled superposition state emits light according to the wavevector combinations of the Floquet states. Scanning the driving frequencies across resonances of a molecule results in multiplicative enhancements of the output light beams and thus provides a way to measure multidimensional spectra. A primary focus of this research project is using Floquet state spectroscopy to probe the mechanisms of chemical reactions. Creating a Floquet state that contains the same vibrational and electronic states as those driven by chaotic thermal motions allows direct observation and control of a reaction. Cobalamin and a Ru-Ru metal-metal complex are two model compounds that the team is using to test the ability of Floquet state spectroscopy to probe reaction mechanisms. In cobalamin, the challenge is to understand the factors responsible for the 12-orders of magnitude change in the scission rate of the C-Co bond upon binding with a substrate. In the ruthenium complex, the challenge is understanding the mechanism for the amination of C-H bonds. Dissemination of the technology includes working with collaborators to apply Floquet state spectroscopy for complex polymeric materials characterization, disposal of actinide nuclear waste in glasses, femtosecond stimulated Raman studies of photochemical reactions, and development of medical diagnostics for pancreatic cancer. Additional broader impacts include advanced training for graduate students as well as the efforts to broaden participation through the collaboration with Spelman College.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.