Abstract

Two different types of colloidal gold nanoparticles, produced as hydrosol, are recognized from their electronic absorption spectra. Gold
nanorods with aspect ratio in the range between 2 and 4 and average diameter between 10 and 15 nm are produced using AuCl3 and
hydroxylamine. The surface plasmon resonance (SPR) band of gold nanorod undergoes a blue shift of about 50 nm on treatment with
ozone. On the other hand, spherical gold nanoparticles with average diameter around 20 nm are produced from AuCl3 reduced with black
tea infusion. When treated with ozone the SPR band of the spherical gold nanoparticles show a red shift of more than 50 nm. This
demonstrates that the shape of the gold nanoparticles deeply affects their response in the interaction with chemicals in view of the potential

Key words: gold nanoparticles; spherical particles; nanorods; ozone; ozone detection