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Show 83 college of science Few techniques are currently available that can provide information about the structure of a single layer of molecules on a surface. Using Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS), Raman scattering from surface immobilized molecules can be detected. The vibrational frequencies within the Raman spectrum provide insight into the composition and structure of the monolayer. This method involves the use of silica-coated metal nanoparticles to enhance Raman scattering (SERS). Shell-Isolated Nanoparticles (SHINs) can be deposited onto virtually any surface to obtain Raman spectra from surface molecules of interest. Silica-coated gold nanoparticles were syn-thesized having a maximum plasmon resonance at wavelengths between of 520nm and 540nm, close to the incident laser wavelength of 514.5nm. Several methods of applying the SHINs to surfaces have been tested. Preliminary results show that simple air drying of a concentrated suspension of SHINs on a surface is an effective, albeit slow approach to achieving uniform deposition of particles on the sur-face to provide effective Raman scattering enhancement. Test samples were prepared by depositing a thin polystyrene film onto a glass slide by dip-coating from a dilute solution. After evaporation of the solvent, Raman scattering from the polystyrene-coated slide without SHINs was measured and no measurable spectra could be obtained. SHINs were then deposited on the surface and Raman scatter-ing measured. The SHIN-coated surface produced a spectrum corresponding to that of a concentrated solution of polystyrene. Analysis of the Raman spectra from the SHIN-coated surface showed that SHINs with a smaller diameter (40nm) produced a stronger signal than that of larger SHINs (65nm). Further optimization of the method will involve varying the core metal (Au, Ag), the silica shell thick-ness, and the density of deposited particles, in order to optimize the enhancement of the Raman scat-tering from surface monolayers. SHELL-ISOLATED NANOPARTICLE-ENHANCED RAMAN SPECTROSCOPY AS A METHOD TO ANALYZE SURFACE CHEMISTRY Natascha Knowlton, Jay Kitt (Joel Harris) Department of Chemistry University of Utah UNDERGRADUATE RESEARCH ABSTRACTS Natascha Knowlton Jay Kitt Joel Harris |