Demonstrative experiments about gold nanoparticles and nanofilms: an introduction to nanoscience

An important task of the scientific community is to provide non-specialized audience with explanations about what is nanoscience. Such explanations can be given during public conferences, seminars in high schools or lab work organized with teachers. And very often, the use of an experimental illustration greatly helps to raise the interest and the curiosity of the public. The present article will describe how the authors have used five simple and visual experiments in chemistry and physics to progressively introduce different audiences into the fascination of nanoscience. One experiment is the synthesis of gold nanoparticles with the Turkevich method and shows the progressive appearance of the rubyred colour of the nanometric gold particles. The second and third experiments describe the way for modulating their colour and how to include them into a polymer and form a ruby-red coloured plastic film. The fourth experiment shows that starting from these nanoparticles, it is possible to turn them back into a yellow golden film. The last experiment is based on the optical properties of ultra-thin gold films. Using the plasmon resonance, it is possible to demonstrate that gold change colours from yellow to orange and green when a white light beam is shone on the gold interface. These visual experiments cannot be fully interpreted in front of a large audience but serve for rising curiosity.