Optical properties of Ag and Au nanoparticles dispersed within the pores of monolithic mesoporous silica

W. Cai, H. Hofmeister, T. Rainer, Wei Chen

Research output: Journal article publicationJournal articleAcademic researchpeer-review

51 Citations (Scopus)

Abstract

The optical absorption of silver and gold nanoparticles dispersed within the pores of monolithic mesoporous silica upon annealing at elevated temperatures has been investigated. With decreasing particle size, the surface plasmon resonance position of the particles blue-shifts first and then red-shifts for silver/silica samples, but only red-shifts for gold/silica samples. This size evolution of the resonance position is completely different from that previously reported for fully embedded particles. We assume a local porosity at the particle/matrix interface, such that free surface of particles within the pores may be in contact with ambient air, and present a two-layer core/shell model to calculate the optical properties. These calculations also consider deviations from the optical constants of bulk matter to account for corresponding effects below about 10 nm particle size. From the good agreement between experimental results and model calculations, we conclude a peculiar particle/ambience interaction dominating the size evolution of the resonance. Because of the difference of core electron structure, the relative importance of the effects of local porosity and free surface, respectively, are different for silver and gold. For silver, the effect of the local porosity is stronger, but for gold the opposite is found.
Original languageEnglish
Pages (from-to)443-453
Number of pages11
JournalJournal of Nanoparticle Research
Volume3
Issue number5-6
Publication statusPublished - 1 Dec 2001
Externally publishedYes

Keywords

  • Dispersions
  • Interface interaction
  • Mesoporous silica
  • Metal nanoparticles
  • Optical absorption

ASJC Scopus subject areas

  • Bioengineering
  • Atomic and Molecular Physics, and Optics
  • Chemistry(all)
  • Modelling and Simulation
  • Materials Science(all)
  • Condensed Matter Physics

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