Inside a glow stick is a thin glass vial containing chemicals. When you bend the stick you’re breaking this vial open, releasing the chemicals into the rest of the glow stick, where other chemicals react with them and release light. Some chemical reactions produce light, known as ‘chemiluminescence’. Usually the vial contains a solution phenyl oxalate ester and a fluorescent dye – which will determine the colour of the glow stick – while the surrounding tube contains a solution of hydrogen peroxide. Mixing these compounds causes the electrons to rise to a higher energy level and return to their normal state, releasing energy as light as they do.
