A glow stick is a self-contained, short-term light-source. It consists of a translucent
plastic tube containing isolated substances that, when combined, make light through chemiluminescence,
so it does not require an external energy source. The light cannot be turned off, and
can be used only once. Glow sticks are often used for recreation, but may also be relied
upon for light during military, police, fire, or EMS operations.
History Cyalume was invented by Frank Arthen and Laszlo
J. Bollyky of American Cyanamid, based on work by Edwin A. Chandross of Bell Labs. Other
early work on chemiluminescence was carried out at the same time, by researchers under
Herbert Richter at China Lake Naval Weapons Center.
Several US patents for "glow stick" type devices were received by various inventors. Most of
these are assigned to the US Navy. The earliest patent lists Bernard Dubrow and Eugene Daniel
Guth as having invented a Packaged Chemiluminescent Material in June 1965. In October 1973, Clarence
W. Gilliam, David Iba Sr., and Thomas N. Hall were registered as inventors of the Chemical
Lighting Device. In June, 1974 a patent for a Chemiluminescent Device was issued with
Herbert P. Richter and Ruth E. Tedrick listed as the inventors.
In January 1976, a patent was issued for the Chemiluminescent Signal Device, with Vincent
J. Esposito, Steven M. Little, and John H. Lyons listed as the inventors. This patent
recommended a single glass ampoule that is suspended in a second substance, that when
broken and mixed together, provide the chemiluminescent light. The design also included a stand for
the signal device so it could be thrown from a moving vehicle and remain standing in an
upright position on the road. The idea was this would replace traditional emergency roadside
flares and would be superior, since it was not a fire hazard, would be easier and safer
to deploy, and would not be made ineffective if struck by passing vehicles. This design,
with its single glass ampoule inside a plastic tube filled with a second substance that when
bent breaks the glass and then is shaken to mix the substances, most closely resembles
the typical glow stick sold today. In December 1977 a patent was issued for a
Chemical Light Device with Richard Taylor Van Zandt as the inventor. This design alteration
features a steel ball that shatters the glass ampoule when the glow stick is exposed to
a predetermined level of shock; an example of its use being that an arrow can be flown
dark but illuminate its landing location upon sudden deceleration.
Uses Practical applications
Glow sticks are used for many purposes. They are waterproof, do not use batteries, generate
negligible heat, are inexpensive, and are reasonably disposable. They can tolerate high
pressures, such as those found underwater. They are used as light sources and light markers
by military forces, campers, and recreational divers. Glow sticks are considered the only
light source that is safe for use immediately following any catastrophic emergency.
Entertainment
Glowsticking is the use of glow sticks in dancing. This is one of their most widely
known uses in popular culture, as they are frequently used for entertainment of course,
at parties, concerts, and dance clubs. They are used by marching band conductors for evening
performances; glow sticks are also used in festivals and celebrations around the world.
Glow sticks also serve multiple functions as toys, readily visible night-time warnings
to motorists, and luminous markings that enable parents to keep track of their children. Yet
another use is for balloon-carried light effects. Glow sticks are also used to create special
effects in low light photography and film. The Guinness Book of Records says the world's
largest glow stick, 8 ft 4 in tall, was built and illuminated at the opening ceremony of
the second Bang Face Weekender at a holiday park in Camber Sands, East Sussex, England,
on April 24, 2009.
How it works Glow sticks give off light when two chemicals
are mixed. The sticks consist of a tiny, brittle container within a flexible outside container.
Each container holds a different solution. When the outer container is flexed, the inner
container breaks, allowing the solutions to combine, causing the necessary chemical reaction.
After breaking, the tube is shaken to thoroughly mix the two components.
In glow sticks, phenol is produced as a byproduct. It is advisable to keep the mixture away from
skin and to prevent accidental ingestion if the glow stick case splits or breaks. If spilled
on skin, the chemicals could cause slight skin irritation, swelling, or, in extreme
circumstances, vomiting and nausea. Some of the chemicals used in older glow sticks were
thought to be potential carcinogens. The sensitizers used are polynuclear aromatic hydrocarbons,
a class of compounds known for their carcinogenicity. Chemistry
The glow stick contains two chemicals and a suitable dye. The chemicals inside the plastic
tube are a mixture of the dye and diphenyl oxalate. The chemical in the glass vial is
hydrogen peroxide. By mixing the peroxide with the phenyl oxalate ester, a chemical
reaction takes place, yielding two molecules of phenol and one molecule of peroxyacid ester.
The peroxyacid decomposes spontaneously to carbon dioxide, releasing energy that excites
the dye, which then relaxes by releasing a photon. The wavelength of the photon—the
color of the emitted light—depends on the structure of the dye. The reason the reaction
is so slow and releases only light, not heat, is that the reverse 2+2 photocycloaddition
of 1,2-dioxetanedione is a forbidden transition and cannot proceed through a regular thermal
mechanism.
By adjusting the concentrations of the two chemicals, manufacturers can produce glow
sticks that either glow brightly for a short amount of time or more dimly for an extended
length of time. This also allows design of glow sticks that perform satisfactorily in
hot or cold climates, by compensating for the temperature dependence of reaction. At
maximum concentration, mixing the chemicals results in a furious reaction, producing large
amounts of light for only a few seconds. Heating a glow stick also causes the reaction to proceed
faster and the glow stick to glow more brightly for a brief period. Cooling a glow stick slows
the reaction a small amount and causes it to last longer, but the light is dimmer. This
can be demonstrated by refrigerating or freezing an active glow stick; when it warms up again,
it will resume glowing. The dyes used in glow sticks usually exhibit fluorescence when exposed
to ultraviolet radiation—even a spent glow stick may therefore shine under a black light.
After activation, the glow sticks gradually shift their emission spectral distribution
somewhat towards red. The light intensity is high just after activation, then exponentially
decays. Leveling of this initial high output is possible by refrigerating the glow stick
before activation.
A combination of two fluorophores can be used, with one in the solution and another incorporated
to the walls of the container. This is advantageous when the second fluorophore would degrade
in solution or be attacked by the chemicals. The emission spectrum of the first fluorophore
and the absorption spectrum of the second one have to largely overlap, and the first
one has to emit at shorter wavelength than the second one. A downconversion from ultraviolet
to visible is possible, as is conversion between visible wavelengths or visible to near-infrared.
The shift can be as much as 200 nm, but usually the range is about 20-100 nm longer than
the absorption spectrum. Glow sticks using this approach tend to have colored containers,
due to the dye embedded in the plastic. Infrared glow sticks may appear dark-red to black,
as the dyes absorb the visible light produced inside the container and reemit near-infrared.
Fluorophores used 9,10-Diphenylanthracene emits blue light
1-chloro-9,10-diphenylanthracene) and 2-chloro-9,10-diphenylanthracene) emit blue-green light more efficiently than
nonsubstituted DPA 9,10-Bis(phenylethynyl)anthracene emits green
light with maximum at 486 nm 1-Chloro-9,10-bis(phenylethynyl)anthracene
emits yellow-green light, used in 30-minute high-intensity Cyalume sticks
2-Chloro-9,10-bis(phenylethynyl)anthracene emits green light, used in 12-hour low-intensity
Cyalume sticks 1,8-dichloro-9,10-bis(phenylethynyl)anthracene
emits yellow light, used in Cyalume sticks Rubrene emits orange-yellow at 550 nm
2,4-di-tert-butylphenyl 1,4,5,8-tetracarboxynaphthalene diamide emits deep red light, together with
DPA is used to produce white or hot-pink light, depending on their ratio
Rhodamine B emits red light. It is rarely used, as it breaks down in contact with CPPO,
shortening the shelf life of the mixture. 5,12-Bis(phenylethynyl)naphthacene emits orange
light Violanthrone emits orange light at 630 nm
16,17-(1,2-ethylenedioxy)violanthrone emits red at 680 nm
16,17-dihexyloxyviolanthrone emits infrared at 725 nm
16,17-butyloxyviolanthrone emits infrared N,N'-bis(2,5,-di-tert-butylphenyl)-3,4,9,10-perylenedicarboximide
emits red 1-N,N-dibutylaminoanthracene emits infrared
6-methylacridinium iodide emits infrared
See also Tritium illumination
References
External links Glowsticks chemistry