Surface-enhanced Raman spectral study of Au nano-particles/alkanethiol self-assembled monolayers/Au(1 1 1 ) heterostructures

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5 Citations (Scopus)

Abstract

This paper describes Raman spectroscopic investigations of octadecane-thiol (C18H37-SH; OD-mT) and octane-dithiol (HS-C8H16-SH; O-dT) self-assembled monolayers (SAMs) on an epitaxial Au(1 1 1 )/cleaved-mica substrate. The epitaxial Au(1 1 1 ) substrate having nanometer-scale domains increases the enhanced Raman signals of SAMs, whereas the Raman bands are much less intense on the micrometer-scale domains of Au(1 1 1 ). The Raman intensity of the νs(CH2) band is increased for depositions above 4 nm, and takes a maximum at a thickness of 9 nm when gold is vacuum-deposited on the OD-mT SAMs that are formed on micrometer-scale domains. For the O-dT SAMs, Raman band intensity profiles show two features at gold thicknesses of 2 and 9 nm; the latter intensity is about three times greater than that of the former. Atomic force microprobe (AFM) images reveal that 20-30-nanometer-scale islands are formed by 9 nm gold deposition for both SAMs. In contrast, 2 nm gold deposition onto the O-dT SAMs creates striped nanostructures (ca. 7 nm in spacing). The results suggest that the specific nanostructures formed by post-deposition of gold serve to enhance the SAMs Raman signals.

Original languageEnglish
Pages (from-to)4352-4356
Number of pages5
JournalSurface Science
Volume600
Issue number18
DOIs
Publication statusPublished - 2006 Sep 15

Keywords

  • Atomic force microprobe
  • Au(1 1 1 )
  • Gold nano-particles
  • Self-assembled monolayers
  • Surface enhanced Raman scattering

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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