Evolution study of photo-synthesized gold nanoparticles by spectral deconvolution model: a quantitative approach

Abstract

During the monitoring of the evolution of Au nanoparticles photo-synthesized via a conventional long-wave UV-visible irradiation (200 nm < λ < 600 nm) in an aqueous solution, two independent growth progresses of nanocrystals were observed. The first growth progress of nanoparticles was initiated between 90 and 96 h (D-5 samples) and mainly evolved to 10–25 nm in diameter. The second growth progress occurred between 136 and 144 h (D-7 samples) and grew mostly to 3–5 nm in diameter. In the surface plasmon absorption spectra of these samples, a continuous blue-shift of λ_max from 543 nm (D-8 samples) to 525 nm (D-14 samples) was observed. A spectral deconvolution model was employed to quantitatively investigate the peak area variation of the component peaks comprising the absorption spectra. It can be concluded from the deconvoluted data of the peak areas for the component peaks that the blue-shift phenomenon is due to the contribution of the second growth progress of Au nanoparticles. If the second growth progress no longer develops, the blue-shift phenomenon of the surface plasmon absorption peak is found to cease.