What is Fluorescence? Fluorescence is the ability of certain
chemicals to give off visible light after absorbing radiation
which is not normally visible, such as ultraviolet light. This
property has led to a variety of uses. Let’s shed some further
light on this topic; consider the omnipresent “fluorescent”
lights. Just how do they work? Fluorescent tubes contain a small
amount of mercury vapor. The application of an electric current
causes a stream of electrons to traverse the tube. These collide
with the mercury atoms which become energized and consequently
emit ultraviolet light. The inside of the tube is coated with a
fluorescent material, such as calcium chlorophosphate, which
converts the invisible ultraviolet light into visible light. The
same idea is used to produce color television pictures. The
screen is coated with tiny dots of substances which fluoresce in
different colours when they are excited by a beam of electrons
which is used to scan the picture. But fluorescent materials had
practical uses