Phosphorescence is the process by which materials emit light after absorbing radiation or energy. It was first observed in the 17th century but not studied scientifically until the 19th century. Phosphorescent materials store absorbed energy and release it slowly as light over minutes or hours by trapping electrons in an excited state. There are two types of photoluminescence - fluorescence which emits light quickly, and phosphorescence which emits light slowly. Common phosphorescent materials include zinc sulfide and strontium aluminate.

1. PHOSPHORESCENCE
By: Inés Vanhille, Inés Mili & Paula
Escobosa

2. INDEX
• Definition
• Historical background
• How phosphorescence works
• Photoluminescence: fluorescence and phosphorescence
• Chemiluminescence
• Materials used
• Phosphorescence is sea creatures

3. DEFINITION
• Phosphorescence is luminosity that is caused by the
absorption of radiations.
• In simple terms, phosphorescence is a process in
which energy absorbed by a substance is released in
the form of light.

4. HISTORICAL BACKGROUND
• The term ‘phosphor’ has been used since the Middle
Ages
• Phosphorescence was first observed in the 17th
century but was not studied scientifically until the
19th century.
• The study of phosphorescent materials led to the
discovery of radioactivity in 1896.

5. HOW PHOSPHORESCENCE WORKS
 Phosphorescent materials store and re-emit light
because of their unusual property of trapping
electrons in a higher state of movement.
 Phosphorescent materials trap their electrons in a
higher energy state for minutes or even hours.

6. PHOTOLUMINESCENCE: FLUORESCENCE &
PHOSPHORESCENCE
 Fluorescence and phosphorescence
are two forms of
photoluminescence.
Photoluminescence is the emission
of light arising from excited
electronic states following
absorption of light
 Many important applications based
on photoluminescence have been
developed

7. CHEMILUMINESCENCE
• It is a process which is commonly mistaken for
phosphorescence.
• Chemiluminescence is the production of light from a
chemical reaction. Two chemicals react to form an
excited intermediate, which breaks down releasing
some of its energy.

8. MATERIALS USED
• Common pigments used
in phosphorescent
materials include zinc
sulfide and strontium
aluminate.
• Strontium aluminate has
a luminance
approximately 10 times
greater than zinc sulfide.

9. PHOSPHORESCENCE IN SEA CREATURES
• Jellyfish, as well as various species of worms, shrimp,
and squid, all produce their own light through
phosphorescence.

10. LUMINOSITY IN WATCHES
• A good example of phosphorescence use is in
watches.
• The material used in watches today is Tritium. In the
past, other materials were used, some with harmful
results to watch factory workers.