Absorption Spectra of Gold Nanoparticle Suspensions

Abstract

Three gold nanoparticle suspensions are obtained, and mean radii in distributions – (6.1 ± 0.2), (11.9 ± 0.3), and (17.3 ± 0.7) nm – are determined by the transmission electron microscopy method. The optical absorption spectra of suspensions are obtained and studied. Calculation of spectral dependences of the absorption index of suspensions at values of the gold complex refractive index taken from the literature showed a significant deviation of experimental and calculated data in the region of 450–800 nm. Spectral dependences of the absorption of suspensions are simulated within the framework of the Mie–Drude theory taking into account the interband absorption in the form of an additional term in the imaginary part of the dielectric permittivity of the Gaussian type. It is shown that to quantify the spectral dependences in the region of the plasmon absorption band of nanoparticles, correction of the parameters of the interband absorption is necessary in addition to the increase of the relaxation parameter of the Drude theory. Spectral dependences of the dielectric permittivity of gold in nanodimensional state are refined from the solution of the inverse problem. The results of the present work are important for predicting the special features of operation of photonic devices and optical detonators based on gold nanoparticles.