Collaborative Research: A Mechanistic Study of Chemical Enhancement in Surface Enhanced Raman Spectroscopy and Graphene Enhanced Raman Spectroscopy

合作研究：表面增强拉曼光谱和石墨烯增强拉曼光谱化学增强的机理研究

• 批准号: 1707657
• 负责人: Lasse Jensen
• 金额: $ 19.48万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-15 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1707657&HistoricalAwards=false
• 关键词: Collaborative; Research; Mechanistic; Study; Chemical

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Cronin at University of Southern California and Professor Jensen at Pennsylvania State University investigate the use of Raman spectroscopy as a powerful tool that measures the energies of specific bond stretches. This technique provide the unique fingerprint for chemical identification. As such, Raman spectroscopy is extremely useful for a number of applications in chemical, environmental and threat detection monitoring. While a highly useful technique, the Raman scattering cross-section of most molecules is extremely small, and this generally limits its potential uses. Surface Enhanced Raman Scattering (SERS) and Graphene Enhanced Raman Scattering (GERS), the techniques investigated in this research project, can be used to improve the small signal intensities, thus making Raman spectroscopy-related applications more practical. In terms of broader impacts Dr. Cronin creates workshops for Los Angeles high school chemistry teachers. He leverages existing relationships between USC and its neighboring high schools (e.g., USC's Good Neighbors Campaign, Joint Education Project, and the Service Learning Program) to increase the attendance from disadvantaged schools (i.e., central Los Angeles inner city schools) serving underrepresented minority groups. The content of the workshop is reformulated to expose underrepresented students to the results and, more importantly, the excitement of research. Research projects for undergraduate students introduce them to fundamental scientific research and give them confidence to pursue careers in science and engineering. A new module devoted to SERS is developed for a new course at USC on nanoscience and nanotechnology, and their research accomplishments are discussed in class and integrated into the curriculum. Professor Jansen uses a website, nanoHub.org, to share their computational tools with scientists outside of his labs. In this collaboration, Professors Cronin and Jensen investigate the mechanism behind the strong spectroscopic responses observed in two surface-based spectroscopic techniques: Surface Enhanced Raman Scattering (SERS) and Graphene Enhanced Raman Scattering (GERS). They use both experimental and computational tools to carefully isolate the enhanced Raman signals caused by Chemical Enhancement (CE) from those signals caused by ElectroMagnetic Enhancement (EM) in order to understand the CE mechanism. Specifically, Professor Cronin's group at USC performs Raman spectroscopy of single molecules on various SERS substrates, which enables a direct comparison with the theoretical calculations preformed at the Jensen's group at PSU. The Raman spectra are collected under various electrochemical conditions in order to explore the role of the molecule-metal energy level alignment and decouple the vibrational-mode-specific chemical enhancement from the uniform chemical enhancement. Professor Jensen's first principles calculations provide a detailed theoretical framework for interpreting chemical enhancement in SERS and GERS spectra to facilitate a better understanding of the chemical enhancement mechanism. Students in both groups experience the interdisciplinary training opportunities. Both groups' are actively engaged in outreach activities to local high school teachers and general public.

在化学系化学测量和成像项目的支持下，南加州大学的Cronin教授和宾夕法尼亚州立大学的詹森教授研究了使用拉曼光谱作为测量特定键拉伸能量的强大工具。 该技术为化学鉴别提供了唯一的指纹图谱。因此，拉曼光谱对于化学、环境和威胁检测监控中的许多应用是非常有用的。 虽然是一种非常有用的技术，但大多数分子的拉曼散射截面非常小，这通常限制了其潜在的应用。表面增强拉曼散射（Sers）和石墨烯增强拉曼散射（GERS），在本研究项目中研究的技术，可以用来提高小信号强度，从而使拉曼光谱相关的应用更实用。在更广泛的影响方面，克罗宁博士为洛杉矶高中化学教师开设了讲习班。他利用南加州大学与邻近高中之间的现有关系（例如，南加州大学的好邻居运动，联合教育项目，和服务学习计划），以增加弱势学校的出勤率（即，洛杉矶市中心的学校）为代表性不足的少数群体服务。研讨会的内容被重新制定，以暴露代表性不足的学生的结果，更重要的是，研究的兴奋。本科生的研究项目向他们介绍基础科学研究，并让他们有信心从事科学和工程职业。一个新的模块，致力于表面增强拉曼光谱在南加州大学纳米科学和纳米技术的新课程开发，他们的研究成果在课堂上讨论，并融入课程。 詹森教授使用一个网站nanoHub.org与实验室外的科学家分享他们的计算工具。 在这项合作中，Cronin教授和詹森教授研究了在两种基于表面的光谱技术中观察到的强光谱响应背后的机制：表面增强拉曼散射（Sers）和石墨烯增强拉曼散射（GERS）。 他们使用实验和计算工具来仔细地将化学增强（CE）引起的增强拉曼信号与电磁增强（EM）引起的那些信号分离，以便理解CE机制。 具体来说，南加州大学的克罗宁教授小组在各种Sers基底上进行了单分子的拉曼光谱分析，这使得可以与PSU的詹森小组进行的理论计算进行直接比较。 在各种电化学条件下收集拉曼光谱，以探索分子-金属能级对准的作用，并将振动模式特定的化学增强与均匀的化学增强解耦。 詹森教授的第一性原理计算为解释Sers和GERS光谱中的化学增强提供了详细的理论框架，以促进对化学增强机制的更好理解。两组学生都有跨学科培训的机会。 这两个团体都积极参与对当地高中教师和公众的外联活动。

项目成果

Interpreting the chemical mechanism in SERS using a Raman bond model

• DOI: 10.1063/1.5138204
• 发表时间: 2020-01-14
• 期刊: JOURNAL OF CHEMICAL PHYSICS
• 影响因子: 4.4
• 作者: Chen, Ran;Jensen, Lasse
• 通讯作者: Jensen, Lasse