The presentation will provide examples of modulating the optical properties of nanomaterials by integrating them into higher order assemblies using electrostatic, supramolecular and covalent approaches.1-7 Various approaches to organize metal nanoparticles by varying the distance and geometry will be discussed in the first part of the presentation, highlighting the role of plasmon coupling and SERS.1-6 Raman signal enhancement of different analyte molecules, when placed at various locations of these assemblies (such as junctions and edges) will be presented.5 Enhancement of Raman signals of pyrene molecule due to the enhanced electric fields on the surface of silver nanoparticles, by controlling the thickness of silica shell, will be discussed.6 Dimeric nanostructures having well defined gap between two silver nanoparticles were prepared and the gap size (d) was varied from 1.5 – 40 nm.6 The experimental Raman enhancement factors at the hot spot follow a 1/dn dependence with n = 1.5, in agreement with the recent theoretical studies by Schatz and co-workers.8 In the second part of the presentation, a novel strategy for inducing chirality to metal nanoparticles, by growing them on peptide nanotube surfaces will be discussed.7 The surface plasmon coupled circular dichroism in these systems originates from the asymmetric organization of Au nanoparticles, resulting in bisignated CD signals. The chiral information and asymmetry at the molecular level on the D- and L-isomers of peptide nanotubes are transferred to gold nanoparticles.

Dr. K. George Thomas, a Scientist of the Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM), had his early schooling in Kerala, India. He received his Masters degree in Chemistry from the University of Pune in 1983 and Ph.D. in Chemistry from the University of Kerala in 1989. He was a Postdoctoral Research Associate at the Photosciences and Photonics Group of the National Institute for Interdisciplinary Science & Technology, Trivandrum during 1989-1994. Subsequently, he joined NIIST, Trivandrum as a Scientist (1994). He has published around sixty five peer-reviewed original research articles, two review articles and contributed three chapters in books. His research interests are in the areas of photochemistry, photophysics and nanomaterials. He is a recipient of the Shanti Swarup Bhatnagar Prize in Chemical Sciences (2006), the MRSI Medal (2005) of the Materials Research Society of India and the CRSI Bronze Medal (2004) of the Chemical Research Society of India. He is a fellow of Indian Academy of Sciences and Honorary Faculty Member of the Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore.

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Jawaharlal Nehru Centre for Advanced Scientific Research
Indo-US Science & Technology Forum
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1. P. K. Sudeep, S. T. S. Joseph and K. George Thomas, J. Am. Chem. Soc., 2005, 127, 6517.
2. S. T. S. Joseph, B. I. Ipe, P. Pramod and K. George Thomas, J. Phys. Chem. B 2006, 110, 150.
3. P. Pramod, S. T. S. Joseph and K. George Thomas, J. Am. Chem. Soc., 2007, 129, 6712.
4. P. Pramod and K. George Thomas, Adv. Mater., 2008, 20, 4300.
5. Jatish Kumar and K. George Thomas, J. Phys. Chem. Lett., 2011, 2, 610.
6. M. Shanthil, Reshmi Thomas, R. S. Swathi and K. George Thomas (J. Phys. Chem. Lett., 2012 submitted)
7. Jino George and K. George Thomas, J. Am. Chem. Soc., 2010, 132, 2502. 8. J. M. McMahon, K. G. Gray, G. C. Schatz, Phys. Rev.B 2011, 83, 115428.

Researchers should cite this work as follows:

• K. George Thomas (2015), "Symposium on Nanomaterials for Energy: Coupled and Chiral Surface Plasmons in Metal Nanostructures," https://nanohub.org/resources/13982.

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