Kinetics and mechanisms of the UV-radiation-assisted formation of gold nanoparticles in HAuCl$_{4}$-doped chitosan solutions

Using methods of optical spectroscopy and small-angle X-ray scattering, the kinetics of the UV radiation-induced formation of gold nanoparticles in HAuCl$_4$-doped water–acid solutions of chitosan has been studied from the very beginning of the reaction. It has been shown that, during synthesis, as the mean size of nanoparticles grows from 2.9 to 6.3 nm, the maximum of the plasmon resonance shifts toward shorter waves (535–523 nm), whereas for a fully formed ensemble of nanoparticles, the reverse trend is observed. It has been found experimentally that the particle size distribution curve changes during synthesis. Based on the inverse problem analysis, conclusions have been drawn regarding the dominant mechanisms behind nanoparticle growth.