Expanding the Capabilities of SERS via Electronic Raman Spectroscopy

在化学系化学测量和成像（CMI）项目的支持下，德克萨斯州A M大学的Matthew谢尔顿和他的团队正在学习如何使用一种特定类型的分子传感器来获得有关化学系统与金属表面的光相互作用时化学系统变化的新信息;即表面增强拉曼散射（Sers）。这些信息对于了解太阳光如何转化为其他形式的能量（如化学燃料）非常重要。分子传感器基于在纳米尺度上精确构造的金属表面。当分子在传感器表面上时，这些金属表面对光的反射被强烈地改变，从而提供关于分子的唯一识别信息。研究小组正在检查由表面反射光引起的背景信号。该背景信号通常被忽略，但可以提供关于当用光照射时在表面处的分子的能量转移的新信息，以及关于分子的身份的附加信息。该项目将为在谢尔顿实验室工作的研究生和本科生提供支持，该团队将从大一开始招募来自代表性不足群体的第一代大学生。谢尔顿和他的小组正在开发光谱技术，以了解金属基底的光化学行为，用于通过表面增强拉曼散射（Sers）进行分子传感。Sers光谱通常测量分子的振动光谱，但金属Sers基底的电子拉曼（eR）响应也会产生传统上被忽略的强“背景”信号。eR信号是金属中电子能量分布的特征，与分子Sers信号相比，可以提供额外的，独特的化学见解。谢尔顿小组的这项研究考察了eR信号如何能够对电子激发和电荷转移的动力学提供详细的光谱见解，即使可能存在有限或模糊的分子信号（例如没有拉曼活性物质）。这些实验将为Sers方法提供基础，该方法可以在低通量连续波（CW）照明（类似于太阳能转换的相关条件）期间提供对光化学和光化学的定量洞察。该奖项反映了NSF的法定使命，并被认为值得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来支持。

With support from the Chemical Measurement and Imaging (CMI) Program in the Division of Chemistry, Matthew Sheldon and his group at Texas A&M University are learning how to use a specific type of molecular sensor to obtain new information about the changes in chemical systems when they interact with light at a metal surface; namely, surface enhanced Raman scattering (SERS). This information is important for understanding how light from the sun can be converted into other forms of energy, such as chemical fuels. The molecular sensors are based on metal surfaces that are precisely structured at the nanometer scale. The reflection of light by these metal surfaces is strongly modified when molecules are on the sensor surface in a way that provides unique, identifying information about the molecules. The research team is examining a background signal caused by the reflection of light from the surface. This background signal is often ignored, but may provide new information about the transfer of energy into or out of molecules at the surface when irradiated with light, as well as additional information about the identity of the molecules. The project will provide support for graduate and undergraduate research students working in the Sheldon laboratory, and the team will work to recruit first-generation college students from underrepresented groups starting in their freshman year.In this work, Matthew T. Sheldon and his group are developing spectroscopic techniques to understand the photochemical behavior of metal substrates that are used for molecular sensing via surface enhanced Raman scattering (SERS). SERS spectroscopy typically measures the vibrational spectrum of a molecule, but the electronic Raman (eR) response of the metal SERS substrate also gives a strong “background” signal that has traditionally been ignored. The eR signal is characteristic of the energy distribution of electrons in the metal and can provide additional, unique chemical insights compared with the molecular SERS signal. This research by the Sheldon group examines how the eR signal can give detailed spectroscopic insights into the dynamics of electron excitation and charge transfer, even when there may be limited or ambiguous molecular signals (e.g. no Raman-active species). The experiments will provide a foundation for SERS methodologies that can provide quantitative insight into photochemistry and photocatalysis during low fluence, continuous wave (CW) illumination that is similar to the conditions that are relevant for solar energy conversion.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.