Fabrication, characterization and optical properties of three-dimensional colloidal gold nanostructures
Date
2008-04-10T06:04:49Z
Authors
Addison, Christopher James
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Abstract
3-Dimensional nanostructures were constructed through the alternate immersion of a
derivatized glass slide in solutions of propanedithiol and gold nanoparticles. The size and
shape of the surface features could be controlled based on the number of nanoparticle
depositions. Characterization of the substrates was performed using W-Vis
spectroscopy and atomic force microscopy. The multilayer nanoparticle substrates were
examined for their suitability in surface-enhanced Raman scattering (SERS) by obtaining
the SERS spectrum of oxazine-720 on the substrates. A dramatic increase in the SERS
signal is noted with increasing nanoparticle layers and reaches a maximum for 11
nanoparticle-layer depositions. The enhancement is attributed to the underlying surface
morphology: Surface features on the order of 40 nm in size yield the greatest SERS
enhancement due to surface plasmon (SP) excitation.
The non-linear optical properties of colloidal nanostructures were examined using second
harmonic generation (SHG). A pronounced second harmonic emission was noted for 13
nanoparticle layers and was attributed to SP excitation to yield surface-enhanced SHG.
The self-assembly of gold nanorods to form 3-dimensional nanostructures was examined.
While the self-assembly was not successful, the aggregated gold nanorods exhibited a
large SERS enhancement. This suggests that the incorporation of gold nanorods into
SERS substrates is a viable avenue for future research.