SERS of semiconducting nanoparticles (TiO 2 hybrid composites)

Anthony Musumeci, David Gosztola, Tara Schiller, Nada M. Dimitrijevic, Vladimiro Mujica, Darren Martin, Tijana Rajh

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Abstract

Raman scattering of molecules adsorbed on the surface of TiO 2 nanoparticles was investigated. We find strong enhancement of Raman scattering in hybrid composites that exhibit charge transfer absorption with TiO 2 nanoparticles. An enhancement factor up to ∼ 10 3 was observed in the solutions containing TiO 2 nanoparticles and biomolecules, including the important class of neurotransmitters such as dopamine and dopac (3,4-dihydroxy-phenylacetic acid). Only selected vibrations are enhanced, indicating molecular specificity due to distinct binding and orientation of the biomolecules coupled to the TiO 2 surface. All enhanced modes are associated with the asymmetric vibrations of attached molecules that lower the symmetry of the charge transfer complex. The intensity and the energy of selected vibrations are dependent on the size and shape of nanoparticle support. Moreover, we show that localization of the charge in quantized nanoparticles (2 nm), demons trated as the blue shift of particle absorption, diminishes SERS enhancement. Importantly, the smallest concentration of adsorbed molecules shows the largest Raman enhancements suggesting the possibility for high sensitivity of this system in the detection of biomolecules that form a charge transfer complex with metal oxide nanoparticles. The wavelength-dependent properties of a hybrid composite suggest a Raman resonant state. Adsorbed molecules that do not show a charge transfer complex show weak enhancements probably due to the dielectric cavity effect.

Original languageEnglish
Pages (from-to)6040-6041
Number of pages2
JournalJournal of the American Chemical Society
Volume131
Issue number17
DOIs
Publication statusPublished - May 6 2009

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Musumeci, A., Gosztola, D., Schiller, T., Dimitrijevic, N. M., Mujica, V., Martin, D., & Rajh, T. (2009). SERS of semiconducting nanoparticles (TiO 2 hybrid composites). Journal of the American Chemical Society, 131(17), 6040-6041. https://doi.org/10.1021/ja808277u