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Surface Plasmon Structures for Surface-Enhanced Raman Scattering

Published online by Cambridge University Press:  01 February 2011

Muhammad Ajmal Khan
Affiliation:
[email protected], Michigan State University, Electrical and Computer Engineering, 2120 Engineering Building, East Lansing, MI, 48824, United States, 517-432-3178
He Huang
Affiliation:
[email protected], Michigan State University, Department of Physics and Astronomy, East Lansing, MI, 48824, United States
B. Shanker
Affiliation:
[email protected], Michigan State University, Department of Electrical and Computer Engineering, East Lansing, MI, 48824, United States
Timothy P. Hogan
Affiliation:
[email protected], Michigan State University, Department of Electrical and Computer Engineering, East Lansing, MI, 48824, United States
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Abstract

Surface-enhanced Raman scattering (SERS) can enhance the intensity of Raman radiation by many orders of magnitude for molecules bound to metallic nanostructures. SERS is generally thought to have been a result of excitation of surface plasmons in nanostructured metal, which greatly enhances local electric field experienced by the molecule. Common SERS substrates fabricated using noble metal colloidal or electrochemically roughened thin films suffer from lack of homogeneity where only few hot spots yield high enhancement. We explore semiconducting nanowires and metallic nanorods as an economical, stable, and uniform SERS substrate for the detection of trace amount of chemicals and bio-species. We utilize bulk synthesized semiconducting nanowires as nano-scale structures that can be coated with noble metals or their colloidal forms to allow for excitation of surface plasmons over broad frequency range. The use of nanowires as SERS substrates has several advantages. The surface properties of these nanowires are highly reproducible and well defined as compared to other systems like colloidal aggregates, electrochemical roughening etc. The synthesized nanowires offer many unique features (sharp vertices, noncircular cross-sections, inter-wire coupling) that may lead to larger field enhancement factors. High density of nanowires means close interaction between adjacent nanowires, which enables SERS to manifest for a broad selection of excitation sources. We have synthesized germanium dioxide and zinc oxide nanowires using the vapor-liquid-solid growth mechanism utilizing a simple quartz tube furnace set up. The nanowires are grown either using thin gold film (5-15 nm) or colloidal gold (20 nm or 60 nm) as catalyst on substrates of silicon, quartz, and alumina. The resulting nanowires are dense (100-300 nm diameter, 10-40 μm long) and randomly distributed on the substrate. The nanowires are subsequently coated with thin films (10-15 nm) of gold that provide plasmons active surface. We have also investigated silver nanorods on glass formed by grazing angle deposition using e-beam evaporation. These nanorods have a diameter of ∼ 50-70 nm with lengths averaging 300-400 nm. These well aligned high aspect ratio and dense structures are ideal for excitation of surface plasmons. The synthesized structures have been characterized using SEM, TEM, and EDS. The SERS studies were conducted using EzRaman-L system from Enwave Optronics, Inc. Silver nanorods and gold-coated nanowires have been found to exhibit significant Raman enhancement for micro-molar concentrations of Rhodamine 6G and Nile blue, and are promising candidates for SERS applications.

Type
Research Article
Copyright
Copyright © Materials Research Society 2008

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References

REFERENCES

[1] Liu, G. L. and Lee, L. P., “Nanowell surface enhanced Raman scattering arrays fabricated by soft-lithography for label-free biomolecular detections in integrated microfluidics,” Applied Physics Letters, vol. 87, pp. 047101, 2005.Google Scholar
[2] Stevenson, C. L. and Vo-Dinh, T., Signal expressions in Raman Spectroscopy, in Modern Techniques in Raman Spectroscopy, Laserna, J. J., Ed. West Sussex: John Wiley and Sons, 1996, pp. 139.Google Scholar
[3] Fleischman, M., Hendra, P. J., and Mcquillan, A. J., Raman-Spectra of Pyridine Adsorbed at a Silver Electrode, Chemical Physics Letters, vol. 26, pp. 163166, 1974.Google Scholar
[4] Moskovits, M., “Surface-enhanced spectroscopy,” Reviews of Modern Physics, vol. 57, pp. 783 LP826, 1985.Google Scholar
[5] Campion, A., Ivanecky, J. E., Child, C. M., and Foster, M., “On the Mechanism of Chemical Enhancement in Surface-Enhanced Raman-Scattering,” Journal of the American Chemical Society, vol. 117, pp. 1180711808, 1995.Google Scholar
[6] Kneipp, K., Kneipp, H., Kartha, V. B., Manoharan, R., Deinum, G., Itzkan, I., Dasari, R. R., and Feld, M. S., “Detection and identification of a single DNA base molecule using surface-enhanced Raman scattering (SERS),” Physical Review E, vol. 57, pp. R6281–R6284, 1998.Google Scholar
[7] Kneipp, K., Kneipp, H., Deinum, G., Itzkan, I., Dasari, R. R., and Feld, M. S., “Single-molecule detection of a cyanine dye in silver colloidal solution using near-infrared surface-enhanced Raman scattering,” Applied Spectroscopy, vol. 52, pp. 175178, 1998.Google Scholar
[8] Kneipp, K., Kneipp, H., Itzkan, I., Dasari, R. R., and Feld, M. S., “Surface-enhanced nonlinear Raman scattering at the single-molecule level,” Chemical Physics, vol. 247, pp. 155162, 1999.Google Scholar
[9] Kneipp, K., Kneipp, H., Manoharan, R., Itzkan, I., Dasari, R. R., and Feld, M. S., “Near-infrared surface-enhanced Raman scattering can detect single molecules and observe ‘hot’ vibrational transitions,” Journal of Raman Spectroscopy, vol. 29, pp. 743747, 1998.Google Scholar
[10] Kneipp, K., Wang, Y., Kneipp, H., Perelman, L. T., Itzkan, I., Dasari, R., and Feld, M. S., “Single molecule detection using surface-enhanced Raman scattering (SERS),” Physical Review Letters, vol. 78, pp. 16671670, 1997.Google Scholar
[11] Nie, S. and Emory, S. R., “Probing Single Molecules and Single Nanoparticles by Surface-Enhanced Raman Scattering,” Science, vol. 275, pp. 11021106, 1997.Google Scholar
[12] Nie, S. M. and Emory, S. R., “Single-molecule detection and spectroscopy by surface-enhanced Raman scattering.,” Abstracts of Papers of the American Chemical Society, vol. 213, pp. 177-Phys, 1997.Google Scholar
[13] Maxwell, D. J., Emory, S. R., and Nie, S. M., “Nanostructured thin-film materials with surface-enhanced optical properties,” Chemistry of Materials, vol. 13, pp. 10821088, 2001.Google Scholar
[14] Lyon, W. A. and Nie, S. M., “Confinement and detection of single molecules in submicrometer channels,” Analytical Chemistry, vol. 69, pp. 34003405, 1997.Google Scholar
[15] Krug, J. T., Wang, G. D., Emory, S. R., and Nie, S. M., “Efficient Raman enhancement and intermittent light emission observed in single gold nanocrystals,” Journal of the American Chemical Society, vol. 121, pp. 92089214, 1999.Google Scholar
[16] Moskovits, M., “Surface-enhanced Raman spectroscopy: a brief retrospective,” Journal of Raman Spectroscopy, vol. 36, pp. 485496, 2005.Google Scholar
[17] Jiang, J., Bosnick, K., Maillard, M., and Brus, L., “Single molecule Raman spectroscopy at the junctions of large Ag nanocrystals,” Journal of Physical Chemistry B, vol. 107, pp. 99649972, 2003.Google Scholar
[18] Prokes, S. M., Glembocki, O. J., Rendell, R. W., and Ancona, M. G., “Enhanced plasmon coupling in crossed dielectric/metal nanowire composite geometries and applications to surface-enhanced Raman spectroscopy,” Applied Physics Letters, vol. 90, pp. 093105–1, 2007.Google Scholar
[19] Yang, J., Wang, W. Z., Ma, Y., Wang, D. Z., Steeves, D., Kimball, B., and Ren, Z. F., “High throughput growth of zinc oxide nanowires from zinc powder with the assistance of sodium chloride,” Journal of Nanoscience and Nanotechnology, vol. 6, pp. 21962199, 2006.Google Scholar
[20] Chaney, S. B., Shanmukh, S., Dluhy, R. A., and Zhao, Y. P., “Aligned silver nanorod arrays produce high sensitivity surface-enhanced Raman spectroscopy substrates,” Applied Physics Letters, vol. 87, pp. 031908–1, 2005.Google Scholar
[21] Micoulaut, M., Cormier, L., and Henderson, G. S., “The structure of amorphous, crystalline and liquid GeO2 ,” Journal of Physics-Condensed Matter, vol. 18, pp. R753–R784, 2006.Google Scholar
[22] Miller, S. K., Baiker, A., Meier, M., and Wokaun, A., “Surface-Enhanced Raman-Scattering and the Preparation of Copper Substrates for Catalytic Studies,” Journal of the Chemical Society-Faraday Transactions I, vol. 80, pp. 1305-&, 1984.Google Scholar