Wavelength-scanned surface-enhanced Raman excitation spectroscopy

Adam D. McFarland, Matthew A. Young, Jon A. Dieringer, Richard P Van Duyne*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

772 Scopus citations

Abstract

A detailed wavelength-scanned surface-enhanced Raman excitation spectroscopy (WS SERES) study of benzenethiol adsorbed on Ag nanoparticle arrays, fabricated by nanosphere lithography (NSL), is presented. These NSL-derived Ag nanoparticle array surfaces are both structurally well-characterized and extremely uniform in size. The WS SERES spectra are correlated, both spatially and spectrally, with the corresponding localized surface plasmon resonance (LSPR) spectra of the nanoparticle arrays. The surface-enhanced Raman scattering (SERS) spectra were measured in two excitation wavelength ranges: (1) 425-505 nm, and (2) 610-800 nm, as well as with the 532-nm line from a solid-state diode-pumped laser. The WS SERES spectra have line shapes similar to those of the LSPR spectra. The maximum SERS enhancement factor is shown to occur for excitation wavelengths that are blue-shifted with respect to the LSPR λ max of adsorbate-covered nanoparticle arrays. Three vibrational modes of benzenethiol (1575, 1081, and 1009 cm -1) are studied simultaneously on one substrate, and it is demonstrated that the smaller Raman shifted peak shows a maximum enhancement closer to the LSPR λ max than that of a larger Raman shifted peak. This is in agreement with the predictions of the electromagnetic (EM) enhancement mechanism of SERS. Enhancement factors of up to ∼10 8 are achieved, which is also in good agreement with our previous SERES studies.

Original languageEnglish (US)
Pages (from-to)11279-11285
Number of pages7
JournalJournal of Physical Chemistry B
Volume109
Issue number22
DOIs
StatePublished - Jun 9 2005

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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