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The lightsticks are nice toys for children and recall, in little scale, the famous "light swords" used in "Star Wars".
They are also known as "starlight".
They are used to make bracelets and necklaces for children and decorations for feasts and parties.

A lightstick is a hollow, 10-20 cm long cylinder made of a luminescent silicone that contains two liquid chemical substances that react and produce light of a colour (yellow, blue, red,...All colours are possible) depending on the reagents mixture employed.

To produce the light, it's enough to bend the stick to mix the two compounds that start to react.

The products are OXYGEN PEROXIDE (H2O2) and ETHER, an organic molecule or the type R-O-R' (where R and R' are two different or equal alkyl groups) that are unstable for their high energy content.
So, these molecules tend to decompose giving their energy to the FLUORESCENT COLORANT contained in the silicone, whose electrons (e-) pass from their fundamental state to an excited one, that they tend to lose within a variable period, from a fraction of second to many minutes.
The reaction that causes this excitation is named CHEMILUMINESCENCE and the colorant that generates the various colours is FLUORESCENT.

The excited state of the colorant doesn't finish with an unique emission of energy equal to the received amount (like in all normal objects) but occurs in various steps, in part, with simple THERMAL energy emission and, for the rest, with the emission of RADIATIVE energy, i.e. light.
But this emitted light, being only part of the initial adsorbed energy, has, consequently, a minor frequency and it's visible by our eyes in the various colours we know.

This fluorescence is also what makes visible many objects in the darkness (like the hours and the hands of a clock) because they slowly release, in the absence of sunlight, the previously adsorbed energy as light of minor frequency (and higher wavelength).

This phenomenon is reversible because, when all the radiating energy has been emitted, another exposition to the day light "recharges" the fluorescent colorant of light energy to be again visible in a new darkness situation.

The chemiluminescence of the lightstick, instead, lasts only for 24 hours, generally, until the two reagents have completed their reaction and it's not reversible.
To get a higher endurance, we can store the lightsticks in a freezer, to slow down the reaction.

Learn more about this author, Aldo Bonincontro.
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