Glow in the Dark. #The science behind glow in the dark products

Glow in the dark
powders, glow sticks,
ropes etc. are all fun
examples of products
using luminescence.
The Science Behind
Glow in the Dark
"Glow in the dark" falls
under several different
sciences including:
Photoluminescence by
definition is the
emission of light from
a molecule or atom
that has absorbed
electromagnetic
energy: examples
include fluorescence
and phosphorescence
materials. The glow in
the dark plastic
constellation kits that
you stick on your wall
or ceiling are an
example of a
photoluminescence
based product.
Bioluminescence is the
light emitted by living
organisms using an
internal chemical
reaction (think deep
sea creatures)
Chemiluminescence is
the emission of light
without the emission
of heat as the result of
a chemical reaction
(for example
glowsticks),
Radioluminescence is
created by the
bombardment of
ionizing radiation.
Chemiluminescence and
photoluminescence are
behind the majority of
glow in the dark products.
According to Alfred
University professors,
"the distinct difference
between chemical
luminescence and photo
luminescence is that for
light to work via chemical
luminescence a chemical
reaction has to occur,
however during photo
luminescence light is
released without a
chemical reaction.
Glow in the Dark -
History
Phosphorus and its
various compounds are
phosphorescents, or
materials that glow in the
dark. Before knowing
what phosphorus was, its
glowing properties have
been reported in ancient
writings. The oldest
known written
observations were made
in China, dating back to
1000 B.C. regarding
fireflies and glow-worms.
In 1602, Vincenzo
Casciarolo, discovered the
phosphorus glowing
"Bolognian Stones" just
outside of Bologna that
started the first scientific
study of
photoluminescence.
Phosphorus was first
isolated in 1669 by
German physician Hennig
Brand. Brand was an
alchemist who was
attempting to change
metals into gold when he
isolated phosphorus. All
photoluminescence glow
in the dark products
contain phosphor. To
make a glow in the dark
toy, toymakers use a
phosphor that is
energized by normal light
and that has a very long
persistence - the length of
time it glows. Zinc Sulfide
and Strontium Aluminate
are the two most
commonly used
phosphors.
Glowsticks
Several patents were
issued for
"Chemiluminescent Signal
Devices" during the early
seventies that were used
for naval signaling.
Inventors, Clarence Gilliam
and Thomas Hall patented
the first Chemical Lighting
Device in October, 1973
(Patent 3,764,796).
However, it is not clear
who patented the very
first glowstick designed
for play.
In December, 1977 a
patent was issued for a
Chemical Light Device to
inventor Richard Taylor
Van Zandt (US Patent
4,064,428). Zandt's
design was the first to add
a steel ball inside the
plastic tube that when
shook would break the
glass ampoule and start
the chemical reaction.
Many toy glowsticks were
then built based on this
design.
Glow in the Dark Pigs
Scientists in Taiwan say
they have bred three pigs
that "glow in the dark".
Photoluminescence
Spectroscopy
Photoluminescence
spectroscopy
is a contactless,
nondestructive method of
probing the electronic
structure of materials. The
photo to the right depicts
photoluminescence
materials spread on 7-
inch wide roll. This is
from a patent pending
technology developed at
Pacific Northwest National
Laboratory that uses small
organic molecule
materials to create organic
light-emitting devices
(OLEDs) and other
electronics.