A Cyalume lightstick is made of a flexible plastic tube containing a
thin-walled glass tube. Inside the glass tube is a solution of hydrogen peroxide, H2O2,
dissolved in a phthalic ester. Outside the glass tube is a solution containing a phenyl
oxalate ester and a fluorescent dye. (In the yellow-green lightsticks the dye is
9,10-bis(phenylethynyl)anthracene.) When the lightstick is bent, the thin-walled glass
tube breaks and its contents mix with the solution outside. Then, the H2O2
reacts with the phenyl oxalate ester:
During the reaction, an intermediate
forms that transfers energy to the dye molecules. The energized dye molecules release this
energy as visible light. The process in which energy from a chemical reaction is released
directly as light is called chemiluminescence.