Plasmonic Properties and Size Programming: A Quantitative Study for Photosynthesized Gold Nanoparticles

Abstract

A novel two-component peak quantitative spectra deconvolution model is employed to elucidate the relationship between the plasmonic properties and the concentration-dependent Au nanocrystals nucleation. The reactions with the initial concentration of starting reagent NaAuCl 4 from 0.75 mM to 0.1 mM are monitored. The peak area variation between component peak (b), large size nanoparticles (d ³ 8.1 nm), and component peak (a), small size nanoparticles (d £ 8.0 nm), demonstrates that the initial concentration of NaAuCl 4 plays a decisive factor to determine the (b/a) ratio, i.e. the growth progresses of Au nanoparticles. If the initial concentration of NaAuCl 4 is higher than 0.2 mM, two independent growth progresses of Au nanoparticles are observed, and a continuous l max blue-shift of surface plasmon absorption peak accompanied with the second growth progress is measured. On the other hand, in the reactions with the initial concentration of NaAuCl 4 lower than 0.2 mM, only one crystal growth progress of Au nanoparticles is shown, and the blue-shift phenomenon of absorption peak induced by the second crystal growth progress no longer exists.