Surface-enhanced Raman spectroscopy of self-assembled monolayers: Sandwich architecture and nanoparticle shape dependence

Christopher J. Orendorff, Anand Gole, Tapan K. Sau, Catherine Jones Murphy

Research output: Contribution to journalArticle

Abstract

Surface enhanced Raman scattering (SERS) spectra of 4-mercaptobenzoic acid (4-MBA) self-assembled monolayers (SAMs) on gold substrates is presented for SAMs onto which gold nanoparticles of various shapes have been electrostatically immobilized. SERS spectra of 4-MBA SAMs are enhanced in the presence of immobilized gold nanocrystals by a factor of 107-109 relative to 4-MBA in solution. Large enhancement factors are a likely result of plasmon coupling between the nanoparticles (localized surface plasmon) and the smooth gold substrate (surface plasmon polariton), creating large localized electromagnetic fields at their interface, where 4-MBA molecules reside in this sandwich architecture. Moreover, enhancement factors depend on nanoparticle shape and vary by a factor of 102. This SERS geometry offers large surface enhancements for molecules adsorbed onto planar substrates and could be quite useful for determining chemical information for poor Raman scatterers from assays on 2-D substrates.

Original languageEnglish (US)
Pages (from-to)3261-3266
Number of pages6
JournalAnalytical chemistry
Volume77
Issue number10
DOIs
StatePublished - May 15 2005
Externally publishedYes

ASJC Scopus subject areas

  • Analytical Chemistry

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