Narrowing the Plasmonic Sensitivity Distribution by Considering the Individual Size of Gold Nanorods

The
plasmonic nanoparticle sensitivity, sensing volume, and the
signal-to-noise ratio are strongly dependent on the nanoparticle dimensions.
It is difficult to chemically produce or purify nanoparticles with
a size variation of less than 10%. This size variation induces a systematic
error in sensing experiments that can be reduced when the exact size
of each individual nanoparticle is known. In this work, we show how
the size of gold nanorods can be estimated directly from the optical
spectra of single nanoparticles by using the increase of radiation
damping with the nanoparticle size. We verify our approach by comparing
these spectrally estimated sizes with the precise sizes of exactly
the same gold nanoparticles using scanning electron microscopy. Our
method of estimating individual particle dimensions from spectroscopic
data reduces the error in plasmonic sensing experiments by as much
as 30%.