IngentaConnect Aligned Silver Nanorod Arrays as Substrates for Surface-Enhanced ...

Authors: Leverette, C.L.¹; Jacobs, S.A.¹; Shanmukh, S.²; Chaney, S.B.³; Dluhy, R.A.²; Zhao, Y.P.³

Source: Applied Spectroscopy, Volume 60, Issue 8, Pages 196A-216A and 833-950 (August 2006) , pp. 906-913(8)

Publisher: Society for Applied Spectroscopy

Abstract:

Preferentially aligned silver nanorod arrays prepared by oblique angle vapor deposition were evaluated as substrates for surface-enhanced infrared absorption (SEIRA) spectroscopy. These nanorod arrays have an irregular surface lattice and are composed of tilted, cylindrically shaped nanorods that have an average length of 868 nm ± 95 nm and an average diameter of 99 nm ± 29 nm. The overall enhancement factor for chemisorbed organic films of para-nitrobenzoic acid (PNBA) deposited onto the Ag nanorod arrays analyzed by external reflection SEIRA was calculated to be 31 ± 9 compared to infrared reflection-absorption spectroscopy (IRRAS) obtained from a 500 nm Ag film substrate. This enhancement is attributed to the unique optical properties of the nanorod arrays as well as the increased surface area provided by the nanorod substrate. SEIRA reflection-absorbance intensity was observed with both p- and s-polarized incident radiation with angles of incidence ranging from 25° to 80°. The largest intensity was achieved with p-polarization and incident angles larger than 75°. Polarization-dependent ultraviolet/visible/near-infrared (UV/Vis/NIR) spectra of the nanorod arrays demonstrate that the red-shifted surface plasmon peaks of the elongated nanorods may be partially responsible for the observed SEIRA response. The SEIRA detection limit for the Ag nanorod arrays was estimated to be 0.08 ng/cm². Surface-enhanced Raman scattering (SERS) and SEIRA analysis of chemisorbed PNBA utilizing the same nanorod substrate is demonstrated.

Keywords: SURFACE-ENHANCED INFRARED ABSORPTION SPECTROSCOPY; SEIRA; EXTERNAL REFLECTION; P-NITROBENZOIC ACID; PNBA; NANOROD; NANOSTRUCTURE

Document Type: Research article

DOI: 10.1366/000370206778062084

Affiliations: 1: Department of Chemistry and Physics, University of South Carolina Aiken, Aiken, South Carolina 29801 2: Department of Chemistry and Nanoscale Science and Engineering Center, University of Georgia, Athens, Georgia 30602 3: Department of Physics and Astronomy, and Nanoscale Science and Engineering Center University of Georgia, Athens, Georgia 30602

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Aligned Silver Nanorod Arrays as Substrates for Surface-Enhanced Infrared Absorption Spectroscopy