Peak wavelength dependant-localized surface Plasmon Resonance sensitivity

Single-nanoparticle plasmonic sensors utilizing Localized Surface Plasmon Resonance (LSPR) on a single nanoparticle has attracted increasing interesting in recent years. However, variations in plasmonic responses between different nanoparticles have not been fully studied. Here we discuss the LSPR scattering peak wavelength distribution of wet-synthesized, cetyltrimethylammonium bromide (CTAB)-capped Au nanorods. A darkfield microscope system was built to track down LSPR signals of individual nanoparticles. Results showed that peak wavelengths of individual Au nanorods that are synthesized in a same batch are broadly distributed ranging from 600 nm to 850 nm. The standard deviation of peak wavelength location from 20 randomly selected Au nanorods was 50.6 nm. Our investigation also revealed that wavelength shift from different nanorods for the same bulk refractive index change could be significant. In general, the plasmonic detection sensitivity of nanoparticles was found to be proportional to peak wavelength location.