Som Tyagi Group – Drexel University

The molecular level specificity provided by Raman spectroscopy (RS) has made it a widely used spectroscopic tool for the determination of molecular structure and compound identification. Dr. Tyagi’s group has been studying Surface Enhanced Raman Scattering (SERS) in fractal aggregates fabricated from nano-particle printing inks. Fractal aggregates of metallic colloidal particles can provide hyper- enhancement for various linear and nonlinear optical responses, including RS. Such enhancement results from the localization of optical plasmon excitations within small parts (“hot-spots” a few to tens of nm in size) of a fractal aggregate. Since fractals are scale-invariant they, unlike translationally-invariant media, do not support propagating waves and hence can ‘trap’ electromagnetic field in very small volumes. When sufficiently concentrated, the large electromagnetic fields in the hot spots can result in very large SERS enhancement.

NTI: Signs of Success

NTI research programs have been extremely successful at publishing in peer-reviewed journals, resulting in more than 820 articles.

In addition, NTI researchers have been awarded more than 200 federal grants totaling more than $150 million.

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