Animation of a forest under a full moon. Fireflies, glowing yellow, flitter about in the air.
NARRATOR:
Hot summer nights wouldn't be the same without the mesmerising light show provided by fireflies. This phenomenon, known as 'chemiluminescence', is also at the heart of how glow sticks give off their otherworldly light. In the early 1960s, when scientists took the first steps towards developing their own version of a firefly, they knew what was required — a molecule that emits light when it's excited and an energy source to excite that molecule. In chemiluminescence that source is a chemical reaction. Chemicals known as peroxides seemed liked likely participants because of their potential to release large amounts of energy during chemical reactions. The reaction that chemists developed in the '60s to create an efficient glow is still used in todays in glow sticks.
On-screen chemical equations demonstrate the various reactions the narrator describes.
NARRATOR:
A compound called 'oxalate ester' and hydrogen peroxide react to form an unstable chemical called 'peroxyacid ester' as well as phenol. The peroxyacid ester decomposes to form more phenol, and most importantly, a highly energetic ring compound. As this ring compound decomposes into two carbon dioxide molecules, it gives up its energy to the dye molecule which makes it light up in impressive fashion. Every glow stick is like a mini-chemistry set in action. Oxalate ester and colourful dye is in the outer chamber while hydrogen peroxide is in a small vial in the middle. When you crack a glow stick, the glass vial breaks, releasing the peroxide and kick-starting the reaction that leads to the glowing effect.
Shot of a bunch of glow sticks emitting coloured light — yellow, red, purple, blue and green.
NARRATOR:
Different fluorescent dyes make different colours. For example, the common green in most glow sticks comes from 9,10-bis(phenylethynyl)anthracene. To get a blue colour, you can use a dye known as 9,10-diphenylanthracene. Green and yellow glow sticks are a piece of cake. Reds are a bit tougher to produce. Purple made a combination of three dyes is the most difficult colour of all.
Shot of people waving glow sticks at a concert.
(Cheering and applause)
NARRATOR:
So the next time you bask in the light of glow sticks at a concert or a party, take a moment to appreciate that chemistry is behind that out-of-this-world glow.
Text on screen — 'ByteSize Science. Uncover the chemistry all around you. www.bytesizescience.com. Produced by the American Chemical Society. ACS, Chemistry For Life.'