Raman enhancements in coupled nanostructures for TERS imaging

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With this award, the Chemical Measurement and Imaging program of the Division of Chemistry is funding Professor Zachary D. Schultz of the University of Notre Dame to explore ways to enhance the signal from molecular samples being imaged by a scanning probe microscope. A type of light scattering (Raman scattering) can reveal information about the structure of molecules. In a scanning probe experiment, the probe tip can enhance the Raman scattering signal (this is called tip-enhanced Raman scattering, or 'TERS'). Professor Schultz is investigating the origin of Raman signal enhancements observed from nanostructures coupled with tip enhanced Raman scattering (TERS) imaging. The instrumentation and methodology is being used in collaboration with Snite Museum of Art to identify pigments in medieval artwork and aid conservation studies. The incorporation of graduate and undergraduate students in this research provides a platform for promoting measurement science and a training opportunity for the students to gain research skills relevant to academic research and commercial interests.The project focuses on understanding the plasmonic effects that give rise to chemical specific signals in TERS experiments. TERS imaging combined with hyperspectral dark-field microscopy determines the plasmon modes and Raman scattering arising from the interaction of a TERS-tip with various sized and shaped nanoparticles (NPs). The electric fields experienced by molecules around the nanostructures are being studied by vibrational frequency shifts rather than signal intensity. Chemical functionalization of the TERS tip and the surface is being used to study the location of the molecules that give rise to the observed TERS signals. The sensitivity of the TERS measurements is being investigated to determine the possibility of single protein studies. This project has the potential to enable chemical characterization of protein receptors in intact cell membranes.