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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.

The Promise of Nanotechnology

“The use of nanotechnology in consumer products and industrial applications is growing rapidly, with the products listed in the inventory showing just the tip of the iceberg.  How consumers respond to these early products — in food, electronics, health care, clothing and cars — will be a litmus test for broader market acceptance of nanotechnologies in the future.”

–Andrew D. Maynard
Chief Science Advisor, Project on Emerging Nanotechnologies
Woodrow Wilson International Center for Scholars

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