A glow stick consists of a glass vial containing a liquid chemical that is sealed inside a larger plastic tube that contains another solution. When you bend the plastic tube, the glass vial inside breaks and the two solutions mix together. The resulting chemical reaction causes a fluorescent dye to emit light. Light is a form of energy, which can be emitted in a variety of ways. These ways include: Incandescence: The emission of light due to heat (as in a wood fire) Fluorescence and phosphorescence: The emission of light in response to radiation energy (as in a fluorescent light bulb or glow-in-the-dark toys) Laser generation: A laser is a concentrated beam of light from stimulated emission All these ways follow on the same basic principle — an outside source of energy excites atoms, causing them to release particles of light called photons. Specifically, if the atoms are excited enough, the collisions will transfer energy to some of the atom's electrons. When this happens, an electron will be temporarily boosted to a higher energy level (farther away from the atom's nucleus). When it eventually falls back down to its original level (closer to the nucleus), it releases some of its energy in the form of light photons. A glow stick uses a chemical reaction to excite the atoms. This chemical reaction happens when several chemical compounds are allowed to mix. Compounds are substances made up of atoms of different elements, bonded together. When you combine two or more compounds, the various atoms may rearrange themselves to form new compounds. This reaction will cause either a release of energy or absorption of energy. The reaction between the different compounds in a glow stick causes a substantial release of light energy. Atoms in the materials are excited, causing electrons to rise to a higher energy level and then return to their normal levels. When the electrons return to their normal levels, they release energy as light. This process is called chemiluminescence. Light sticks come in a variety of colours. The color of the light is determined by the chemical makeup of the fluorescent dye in the stick. A typical glow stick holds a hydrogen peroxide solution, a solution containing an oxalate ester and a fluorescent dye. Before activating the stick, the two solutions are kept in separate chambers. The oxalate ester and dye solution fills most of the plastic tube itself. The hydrogen peroxide solution, called the activator, is contained in a small, fragile glass vial in the middle of the stick. When you bend the plastic stick, the glass vial inside snaps open, and the two solutions mix. The chemicals react with one another, and the atoms begin emitting light. Here are the details of the reaction if you're interested: The hydrogen peroxide oxidizes the phenyl oxalate ester, resulting in a chemical called phenol and an unstable peroxy acid ester The unstable peroxy acid ester decomposes, resulting in additional phenol and a cyclic peroxy compound The cyclic peroxy compound decomposes to carbon dioxide. This decomposition releases energy to the dye The electrons in the dye atoms jump to a higher level, then fall back down, releasing energy in the form of light The glow stick itself is just a container for the two solutions involved in the reaction. Depending on which chemicals are used, the reaction may go on for a few minutes or for hours. If you heat the solutions, the stick will glow brighter, but for a shorter amount of time. If you cool the light stick, the reaction will slow down, and the light will dim. If you want to preserve your light stick for the next day, put it in the freezer — it won't stop the process, but it will drag out the reaction for a long time. Glow sticks are just one example of an important natural phenomenon - luminescence. Luminescence is any emission of light that oisn't caused by heat. Luminescence is used in neon lights and glow-in-the-dark toys. It's also the principle that lights up a firefly. The military also uses longer-lasting glow sticks. In fact, the government market for glow sticks in the U.S. is about $35 million a year, compared with about $40 million for the novelty market. Resources HTML, graphics & design by Bill Willis 2023