Making Gold Nanoparticles with Lasers

The color of gold nanoparticles depends on their physical size, ranging from light red to a dark bluish/purple. This phenomenon is caused by Plasmon Resonance. There is a cloud of delocalized electrons flying around a metal, and these electrons can react in a coordinated manner to electromagnetic fields (like light). But when the surface of the metal is very small -- like in a nanoparticle -- the electron cloud is can begin to oscillate across the surface. If the wavelength of light is just right it will resonate with the electron cloud, and that wavelength of light is reflected while all others are transmitted or absorbed. This causes the particle to look a specific color. Or... Ghosts. -------------------------------- Full video with references/sources: #shorts