Essay/Term paper: The luminescence of black light

Essay, term paper, research paper:  Science

The Luminescence of Black Light


Black Light. What is it? It is a portion of the Ultra-Violet Spectrum
that is invisible to our eyes. We can not distinguish it. However, when this
radiation impinges on certain materials visible light is emitted and this is
known as "fluorescence." Fluorescence is visible to the human eye, in that it
makes an object appear to "glow in the dark."
There are several sources of ultra-violet light. These sources are: the
sun, carbon arcs, mercury arcs, and black lights. In most cases, the production
of ultra-violet light creates a reasonable amount of heat.
Many materials exhibit the peculiar characteristic of giving off light
or radiant energy when ultra-violet light is allowed to fall upon them. This is
called luminescence. In most cases, the wave length of the light radiated is
longer than that of the ultra-violet excitation but a few exceptions have been
found.
The quantum theory attempts to explain this property by contending that
a certain outside excitation causes an electron to jump from one orbit to
another. It is then in an unstable environment causing it to fall back into its
original orbit. This process releases energy, and if it is in the visible part
of the spectrum, we have a transient light phenomenon. Ultra-violet light is an
exciting agent which causes luminescence to occur.
There are many materials which exhibit fluorescent characteristics.
Many of which are even organic. Teeth, eyes, some portions of the skin, and
even blood exhibit fluorescent qualities. Naturally occurring minerals such as:
agate, calcite, chalcedony, curtisite, fluorite, gypsum, hackmanite, halite,
opal scheelite, and willemite, also have similar characteristics. These
materials can be used in industries.
The radiance of ultraviolet light is measured in units called
"Angstrom." The intensity of ultraviolet fluorescence is the greatest between
the 5000 and 6000 range. This being the range between the green and yellow hues.
Ultra violet light is not readily visible. It is not visible because
certain materials reflect it. Ultra-violet light is made visible due to the
fact that it causes a reaction at the atomic level. When it strikes the atom,
some of the electrons are sent into other orbits. This then creates an unstable
situation which causes the electron to fall back into its place. This process
produces energy, and this is what is seen. This discharge of energy is what
creates the "glow" that is seen. I had no idea that light could cause such an
strong reaction on something. That something being an atom is even more
profound. Ultraviolet light causes the atom to lose a subatomic particle then
regain it, and give off energy in the form of visible light. This is just
amazing.