In this work, we report the size-dependent blue shift of the silver nanoparticle plasmon band in aqueous solution by means of UV/VIS spectroscopy. An oxidative dissolution scheme allows a gradual decrease in the particle sizes by controlled oxidation during recording of the optical spectra. Hence, all sizes until complete dissolution can be obtained on the same substrate, thereby avoiding substrate-to-substrate variations and greatly increasing the size resolution. Cyanide and cysteamine are strong nucleophiles (electron pair donors) that deposits negative charge onto the NP surface. A 1/R-dependence of the plasmon peak energy is seen, which is interpreted as an increase in the free electron density of the nanoparticles. Utilization of the size-dependent electronic contribution to the optical response in nanoplasmonic sensors is shown to be a promising extension to improve the sensitivity and specificity, as compared to traditional refractive index sensing.
Proceedings of Nanotech 2014, 2014
Plasmonics; Biosensor; Blue shift; Nanoparticles; Cyanide