Why does lemonade look yellow, but grape juice looks purple? It has to do with the molecules in the juice – the colored materials, or pigments, in lemons and those from grapes are different molecules, and absorb different colors (wavelengths) of light. You see the colors that are not absorbed. The particular wavelengths absorbed or not are a characteristic of the substance and are used as a way to categorize substances. This is another way that scientists determine structure (like what you witnessed in this activity using X-crystallography). Electromagnetic radiation, including visible light, can supply energy, depending on its wavelength, and we can use the energy of light, both absorbed and emitted, to understand something about the molecules in a substance. You are going to do this today!
In this activity, you will use a chemical reaction that converts everyday materials to a substance that glows under special lights. That substance is a type of ‘nanomaterial’ called a ‘carbon quantum dot’ or C-dot, for short. Nanoparticles like C-dots can be billions of times smaller than the diameter of a hair. Nanoparticles are of great interest to scientists because they “fluoresce” (or glow) under ultraviolet light (like a blacklight). The color of the glow can be changed by making the particle larger or smaller, or changing the types of atoms that are in it. Can you make C-dots that glow? What can we do with them? Let’s investigate!
