Open AccessSubstrate effect on refractive index dependence of plasmon resonance for individual silver nanoparticles observed using darkfield microspectroscopy
Author(s) -
Adam Curry,
Greg J. Nusz,
Ashutosh Chilkoti,
Adam Wax
Publication year - 2005
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/opex.13.002668
Subject(s) - surface plasmon resonance , refractive index , materials science , optics , silver nanoparticle , nanoparticle , plasmon , substrate (aquarium) , localized surface plasmon , surface plasmon , resonance (particle physics) , mie scattering , nanotechnology , optoelectronics , light scattering , physics , scattering , oceanography , particle physics , geology
We use optical darkfield micro-spectroscopy to characterize the plasmon resonance of individual silver nanoparticles in the presence of a substrate. The optical system permits multiple individual nanoparticles to be identified visually for simultaneous spectroscopic study. For silver particles bound to a silanated glass substrate, we observe changes in the Plasmon resonance due to induced variations in the local refractive index. The shifts in the plasmon resonance are investigated using a simple analytical theory in which the contributions from the substrate and environment are weighted with distance from the nanoparticle. The theory is compared with experimental results to determine a weighting factor which facilitates modeling of environmental refractive index changes using standard Mie code. Use of the optical system for characterizing nanoparticles attached to substrates for biosensing applications is discussed.