Analytical Applications of Surface-Enhanced Hyper-Raman Scattering

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With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professors Camden and Svarovsky of the University of Notre Dame will undertake a study of the analytical applications of the surface-enhanced hyper-Raman scattering (SEHRS) effect and implement a student-driven program to monitor the concentration of uranium in ground water sources. SEHRS is a technique provide unique information about molecules adsorbed on a surface. The success of this work has the potential to impact a wide range of studies, especially the geometry of a molecule adsorbed on a surface differs in complex environments. It can also make a difference in deep-tissue imaging. Furthermore, Professors Camden and Svarovsky and their groups also work on ways to reduce the cost of SEHRS spectrometers, making SEHRS accessible to a wide range of researchers and analytical problems. Students working in these two labs have a great opportunity to learn different skills through collaboration. As a way to engage a new and national K-12 audience in outreach efforts, Professors Camden and Svarovsky also plan to work with the University of Notre Dame's Center for STEM Education together and launch a new Citizen Science project called U-Watch. The program will bring the benefits of surface-based spectroscopy research supported by this grant to a broad audience and could identify potentially dangerous levels of contamination, such as uranium, in ground water drinking sources.In this work, SEHRS is used to provide information that is not available via other techniques. New methods for single-molecule SEHRS are used to probe nanoparticle-adsorbate interactions at the level of single molecules in complex chemical environments. SEHRS nanoparticles also serve as a platform for near-infrared and short-wave-infrared (SWIR) (0.8-2.5 Pm) sensing, imaging, and authentication. The Notre Dame groups also plan to develop the characterization methods needed to pursue the rational design of SWIR tags and apply them to deep-tissue imaging studies. A comparison of SEHRS and surface-enhanced Raman spectroscopy (SERS) shows that SEHRS can be more sensitive than SERS in certain situations. Lastly, they explore the potential for hand-held, field-portable devices capable of recording SEHRS spectra with continuous-wave lasers. Through the supported research, the groups will demonstrate SEHRS as a powerful and practical analytical approach to ultrasensitive detection, imaging, and the elucidation of surface structure and environment.