Optimum massthickness of Ag-nanoparticle film for surface enhanced raman scattering

K. C. Lee, S. T. Pai, Y. C. Chang, M. C. Chen, W. H. Li

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19 Scopus citations

Abstract

Raman scattering from a few monolayers of benzole acid (BA) enhanced by a thin layer of Ag-nanoparticles (AGNs) was studied, using a series of AGN films having different massthickness covering a range from 5 to 50 nm. Surface images taken using an atomic force microscope clearly reveal each individual AGN of average size ∼25 nm. Extinction spectra of the AGN films exhibit a surface-plasma resonance peak at ∼380 nm with a long tail extending to the visible region. When emphasizing the electromagnetic effect, the attenuated total reflection configuration was adopted to obtain an enhanced Raman spectrum. An optimum massthickness for enhancing Raman signal was found to be ∼15 nm. A semi-empirical formula was also developed to estimate the Raman signals from a few monolayers of BA, hence the enhancement factor. The estimated enhancement factor is in the order of 104 for the optimum case. The enhancement is believed to originate from the excitation of surface plasmons (SPs).

Original languageEnglish
Pages (from-to)189-194
Number of pages6
JournalMaterials Science and Engineering B: Solid-State Materials for Advanced Technology
Volume52 B52
Issue number2-3
DOIs
StatePublished - 3 Apr 1998

Keywords

  • Ag nanoparticles
  • Massthickness
  • Raman

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