Phosphorescence is a type of photoluminescence where absorbed energy is released slowly as light. It allows "glow-in-the-dark" materials to store light energy and release it over time. The first scientific observations of phosphorescence were of the Bologna Stone in 1602 and other substances that glow after heating or light exposure. Phosphors are chemicals that emit light when exposed to different wavelengths and are used in fluorescent lights and toys. Phosphorescent paint contains phosphors like zinc sulfide or strontium aluminate and is used for escape paths, decorations, and temperature detection. Tritium, a radioactive hydrogen isotope, is used in watches due to its long-lasting fluorescent glow from

1. PHOSPHORESCENCE
By: Eloy Isidro, Mario García & Kevin Garrido

2. INDEX
1. Definition
2. Discovery
3. Phosphor
4. Chemiluminescence
5. Luminous paint
6. Tritium
7. Materials
8. Phosphoroscope
9. Phosphorescence in nature

3. DEFINITION
• Phosphorescence is a specific type of
photoluminescence related to fluorescence.
• In simple terms, phosphorescence is a process in
which energy absorbed by a substance is released
relatively slowly in the form of light.
• This is in some cases the mechanism used for "glow-
in-the-dark" materials which are "charged" by exposure
to light.
• Phosphorescent materials "store" absorbed energy for
a long time, as the processes required to re-emit
energy occur less often.

4. DISCOVERIES AND SCIENTISTS
The first discovery of phosphorescence which attracted scientific attention was
that of the Bologna Stone (barium sulphide), discovered by the shoemaker
Vincenzo Cascariolo in 1602. This was followed by the discovery of a number of
substances which become luminous either after heating or exposure to light:
• Homberg´s phosphorus(obtained by heating calcium chloride)
• John Canton´s phosphorus(calcium sulphide)
• Balduin´s phosphorus(calcium nitrate).

5. PHOSPHOR
● Phosphor is a chemical compound which emits light when it is exposed to the light
of a different wavelength.
● Sometimes this element can be confused with phosphorus but there are no
similarities between them.
● We can find this element in fluorescent bulbs, toys or safety signs in buildings.

6. CHEMILUMINESCENCE
• Some examples of glow-in-the-dark materials
do not glow by phosphorescence.
• In chemiluminescence, an excited state is
created via a chemical reaction.

7. LUMINOUS PAINT
• Phosphorescent paint is made from phosphors
such as silver-activated zinc sulfide or doped
strontium aluminate.
• Escape paths in aircraft and decorative use
such as "stars" applied to walls and ceilings.
• When applied as a paint or a more
sophisticated coating, phosphorescence can be
used for temperature detection or degradation
measurements known as phosphor
thermometry.

8. Tritium & luminosity in watches
● Tritium is a radioactive isotope of hydrogen very difficult to find on Earth, it was first
discovered in 1934.
● This isotope can damage our health or contaminate the environment, but it is still used
for nuclear weapons or controlled nuclear fusion.
● Also, this material is used in watches because the electrons produced by tritium create
a fluorescent light that can last up to 20 years. Obviously tritium in watches is
hermetically closed inside small glass tubes.

9. MATERIALS
• Common pigments used in phosphorescent
materials include zinc sulfide and strontium
aluminate.
• Everyday examples of phosphorescent
materials are:
• the glow-in-the-dark toys
• stickers
• paint
• clock dials

10. PHOSPHOROSCOPE
• A phosphoroscope is a device used in observing and measuring the
persistence of phosphorescence after the source of radiation has been
removed(after it has been excited).
• It was invented in 1857 by the physicist A.E.Becquerel.

11. Phosphorescence in nature
● Bioluminescence is the emission and production of light by a living organism, this
type of chemiluminescence is produced when a pigment and an enzyme join in a
chemical reaction.
● Bioluminescence is used by animals for communicating, imitating other
organisms, illuminating or even camouflaging.
● Sometimes the sea water can illuminate by some plankton with this kind of
bioluminescence, this is one of the most beautiful events that bioluminescence
can produce.

12. THE END
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