Platinum Nanoparticles Exhibiting Enhanced Raman Scattering

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Researchers from Seoul National University in South Korea have conducted an in-depth study on the properties of platinum nanoparticles, demonstrating their potential for surface-enhanced Raman scattering. The team, led by K. Kim, used a multistep seed-mediated growth method to produce nanoparticles with diameters ranging from 28 to 105 nm. Their findings indicate that these nanoparticles exhibit distinct UV-vis absorption bands and enhanced Raman intensity at specific wavelengths. The researchers attributed the observed phenomena to the electromagnetic and chemical enhancement mechanisms.

Key Takeaways:

  • The researchers prepared platinum nanoparticles with diameters of 28 to 105 nm using a multistep seed-mediated growth method.
  • The nanoparticles exhibited a broad UV-vis absorption band at approximately 330 nm, independent of particle size.
  • Higher Raman intensity was observed at shorter excitation wavelengths from adsorbates on a Pt film made of 105 nm sized Pt particles.
  • The enhancement factor (EF) was determined to be 1.5 x 10^2 at 514.5 nm excitation, although an order of magnitude smaller than earlier studies.
  • The smaller EF value was attributed to the fact that the prepared Pt particles were composed of 7.2 nm sized seed particles.
  • The researchers successfully characterized the SERS characteristics of two typical aromatic thiols, 4-nirobenzenethiol (4-NBT) and 4-aminobenzenethiol (4-ABT).
  • The study found that 4-NBT is barely subjected to photoreaction on a Pt surface, in contrast with that on Ag.
  • The chemical enhancement mechanism was operating alongside the electromagnetic enhancement mechanism in the SERS of 4-ABT on Pt.

Statistics:

  • The diameter of the prepared platinum nanoparticles ranged from 28 to 105 nm.
  • The enhancement factor (EF) was 1.5 x 10^2 at 514.5 nm excitation.
  • The EF value was an order of magnitude smaller than earlier studies on Pt films fabricated with laser-ablated 17 nm sized particles.

Sources:

  • K. Kim, et al., "Surface-Enhanced Raman Scattering on Aggregates of Platinum Nanoparticles with Definite Size," Journal of Physical Chemistry C, 2010;114(43):18679-18685.