Size Controlled Formation of Gold Nanoparticles Using Photochemical Grwoth and Photothermal Size Reduction by 308 nm Laser Pulses

Abstract

We synthesized gold nanoparticles (mean diameter 8.3 nm, standard deviation 2.7 nm) from tetrachloroaurate complex (AuCl4-) solution by 308 nm laser irradiation without the use of any stabilizers. The combination of photochemical particle growth with photothermal particle size reduction by 308 nm laser irradiation resulted in a narrow size distribution. Photothermal size reduction controlled the maximum diameter of gold nanoparticles which existed in the system, and photochemical growth controlled their size distribution. Using this technique, we were able to control the diameter and the size distribution of gold naoparticles. We propose a simple model for estimating the maximum diameter of gold nanoparticles formed in the system by the irradiation of nanosecond laser pulses. The maximum diameter of particles is determined by the competition between heating of a particle by absorbed photon energy and heat dissipation from the particle surface to the surroundings.