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%.