10.1021/acs.jpcc.9b05077.s001
Tatsuya Shoji
Tatsuya
Shoji
Mamoru Tamura
Mamoru
Tamura
Tatsuya Kameyama
Tatsuya
Kameyama
Takuya Iida
Takuya
Iida
Yasuyuki Tsuboi
Yasuyuki
Tsuboi
Tsukasa Torimoto
Tsukasa
Torimoto
Nanotraffic Lights: Rayleigh Scattering Microspectroscopy
of Optically Trapped Octahedral Gold Nanoparticles
American Chemical Society
2019
Rayleigh Scattering Microspectroscopy
vertex-to-vertex configuration
octahedral gold nanoparticles
microspectroscopy
plasmonic nanostructures
Octahedral Gold Nanoparticles
enhancement factors
Monodispersed OGPs
dark-field microscopy
OGP dimer
edge length
Nanotraffic Lights
form dimers
near-infrared laser beam
field vector
polyol method
laser light
color change
finite-difference time-domain calculations
2019-09-09 16:37:03
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Nanotraffic_Lights_Rayleigh_Scattering_Microspectroscopy_of_Optically_Trapped_Octahedral_Gold_Nanoparticles/9786140
We
demonstrate a pronounced color change in the light scattered
from thermally fluctuating optically trapped octahedral gold nanoparticles
(OGPs) in water using a tightly focused near-infrared laser beam.
Monodispersed OGPs with an average edge length of 67 ± 6.5 nm
were synthesized using a polyol method. Using dark-field microscopy,
we observed successive changes of color (i.e., red → green
→ yellow) scattered from the trapped OGPs. We analyzed this
trapping behavior by means of Rayleigh scattering microspectroscopy
and concluded that pairs of OGPs trapped in the potential well interact
with each other to form dimers oriented in the direction of the electric
field vector of the trapping laser light. We theoretically obtained
the absorption and scattering cross sections and the enhancement factors
of the electric field of an OGP dimer in three different configurations
by means of finite-difference time-domain calculations. The calculations
suggest that the dimers become preferentially oriented in a vertex-to-vertex
configuration because of the high polarizability. These findings indicate
that optical tweezers are a promising technique for creating highly
ordered assemblies of plasmonic nanostructures whose coupled states
can be monitored by means of microspectroscopy.