1 research outputs found
Size-Modulation of Plasmonic Nanorings Obtained by the Self-Assembly of Gold Nanoparticles and Block Copolymers
Metal nanoparticles exhibit interesting
optical properties due
to the collective excitation of conduction electrons called the plasmon.
Within appropriate metal nanostructures, cooperative plasmon modes
appear and the resonance plasmon frequency is modified. This article
reports a simple method for the formation of such structures, in the
form of self-assembled nanorings. Rings of alkanethiol-capped gold
nanoparticles are obtained by the Langmuir–Blodgett technique
and a block copolymer (PS-<i>b</i>-P2VP) template. With
this approach, organized nanoparticle arrangements covering a large
surface area are obtained. Furthermore, geometric parameters such
as ring diameter, ring-to-ring separation, and ring width can be systematically
varied by the addition of homopolymer or in situ nanoparticle regrowth.
Optical extinction spectra recorded for the nanoparticle rings depend
both on ring diameter and particle size. In particular, after in situ
particle regrowth, the plasmon extinction spectrum exhibits a red-shift
that increases with ring diameter. Theoretical spectra generated with
the discrete dipole approximation indicate that this spectral shift
can be attributed to plasmon coupling that extends over an increasing
number of particles as the ring is enlarged