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Enhanced Raman Scattering from Nanoparticle-Decorated Nanocone Substrates: A Practical Approach to Harness In-Plane Excitation

Hu, Ying S. and Jeon, Jaeseok and Seok, Tae J. and Lee, Seunghyun and Hafner, Jason H. and Drezek, Rebekah A. and Choo, Hyuck (2010) Enhanced Raman Scattering from Nanoparticle-Decorated Nanocone Substrates: A Practical Approach to Harness In-Plane Excitation. ACS Nano, 4 (10). pp. 5721-5730. ISSN 1936-0851.

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We investigate surface-enhanced Raman scattering (SERS) from gold-coated silicon-germanium nanocone substrates that are decorated with 30-nm spherical gold nanoparticles (AuNPs). Finite-element simulations suggest that individual nanocones generate stronger electromagnetic enhancement with axial polarization (i.e., polarization parallel to the vertical axis of the nanocones) than with transverse polarization (i.e., polarization in the plane of the nanocone substrate), whereas the excitation in a typical Raman microscope is mainly polarized in the transverse plane. We introduce a practical approach to improve the SERS performance of the substrate by filling the valleys between nanocones with AuNPs. Simulations reveal an enhanced electric field at the nanoscale junctions formed between AuNPs and nanocones, and we explain this lateral coupling with a hybridization model for a particle-film system. We further experimentally verify the added enhancement by measuring SERS from trans-1,2-bi-(4-pyridyl) ethylene molecules absorbed onto the substrates. We report over one order-of-magnitude increase in SERS activities with the AuNP decoration (compared to the nanocone substrate without AuNPs) and achieve a spatially averaged enhancement factor of 1.78 x 10^8 at 785-nm excitation. Understanding and implementing the enhancing mechanism of structured metallic surfaces decorated with plasmonic nanoparticles open possibilities to substantially improve the SERS performance of the existing processengineered substrates.

Item Type:Article
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Choo, Hyuck0000-0002-8903-7939
Additional Information:© 2010 American Chemical Society. Received for review June 15, 2010 and accepted August 31, 2010. Published online September 13, 2010. The authors would like to thank P. Nordlander for discussion on the plasmon hybridization in the particle-film system, J. Bokor for discussion on polarization effects in confocal setups, A. Zayak for discussion on the chemical enhancement, A. Schwartzberg for the Raman scan, and S. Noelck for the preparation of the manuscript. This work was financially supported by the Welch Foundation Grant C-1598, DOE DE-FG02-97ER25308 and DARPA SERS S&T Program. The computational work was supported by the Shared University Grid at Rice University funded by NSF Grant EIA-0216467. Y. Hu acknowledges support from the DOE CSGF program.
Funding AgencyGrant Number
Welch FoundationC-1598
Department of Energy (DOE)DE-FG02-97ER25308
Defense Advanced Research Projects Agency (DARPA)UNSPECIFIED
Subject Keywords:Raman scattering, SERS, nanocone substrate, gold nanoparticles, surface plasmon, plasmon hybridization, in-plane excitation
Issue or Number:10
Record Number:CaltechAUTHORS:20150804-112031009
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Official Citation:Enhanced Raman Scattering from Nanoparticle-Decorated Nanocone Substrates: A Practical Approach to Harness In-Plane Excitation Ying S. Hu, Jaeseok Jeon, Tae J. Seok, Seunghyun Lee, Jason H. Hafner, Rebekah A. Drezek, and Hyuck Choo ACS Nano 2010 4 (10), 5721-5730 DOI: 10.1021/nn101352h
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59180
Deposited By: Kristin Buxton
Deposited On:05 Aug 2015 22:48
Last Modified:03 Oct 2019 08:44

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