In the lab at Chalmers, doctoral student Michaela Hošková shows a glass container filled with millions of micrometre-sized gold flakes in a salt solution. Using a pipette, she picks up a drop of the solution and places it on a gold-coated glass plate in an optical microscope. What happens is that the gold flakes in the salty solution are immediately attracted to the substrate but leave nanometre-sized optical spaces between them and the gold platform. The cavities created in the liquid act as resonators in which light bounces back and forth, displaying colours. When the microscope’s halogen lamp illuminates the platform and a spectrometer separates the wavelengths, the different colours of light can be identified.
Photographer: Chalmers University of Technology | Mia Halleröd Palmgren