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

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 NaAuCl₄ from 0.75 mM to 0.1 mM are monitored. The peak area variation between component peak (b), large size nanoparticles (d ≥ 8.1 nm), and component peak (a), small size nanoparticles (d ≤ 8.0 nm), demonstrates that the initial concentration of NaAuCl₄ plays a decisive factor to determine the (b/a) ratio, i.e. the growth progresses of Au nanoparticles. If the initial concentration of NaAuCl₄ is higher than 0.2 mM, two independent growth progresses of Au nanoparticles are observed, and a continuous λ_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 NaAuCl₄ 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.