Explore the concept of light absorption in plants and watch some spinach fluoresce

Grinding the spinach leaves disrupts the normal structure of the leaf cells and releases chlorophyll a. Normally, chlorophyll would absorb light energy that excites an electron which is then transferred to an acceptor molecule. However, in this experiment, the excited electron is not transferred anywhere and the energy is released again as light, i.e. an electron gets excited to a higher energy level by a photon of light and then releases it again when the energy is not transferred anywhere else.