Ultraviolet information

       Ultraviolet light is electromagnetic radiation in a part of the spectrum between X-rays and visible light, approximately 180 nanometers to 400 nanometers. It differs from light only that it's wavelengths are too short to be seen by the human eye. U V-A , or long-wave radiation is 315 nanometers and above. U V-B, or medium-range radiation, is 280 nanometers to 315 nanometers. U V-C, or short wave radiation, is 280 nanometers and below.

       The phenomenon known as fluorescence occurs at the subatomic level by a process called electron excitation. Electrons are subatomic particles that orbit the nucleus of an atom at specific distances known as electron shells. These shells are arranged in layers around the nucleus, the exact number of electrons and their shells depending on the type of atom (element). The electrons contained in the shells nearest the nucleus carry less energy than the electrons in the outer shells.

       When certain atoms are exposed to ultraviolet (UV) light, a photon (particle of light energy) of UV will cause an electron residing in a lower-energy inner electron shell to be temporarily boosted to a higher-energy outer shell. In this condition, the electron is said to be excited. It will then drop back to its original inner electron shell, releasing its extra energy in the form of a photon of visible light. This visible light is the fluorescent color that our eyes perceive. The exact color depends on the wavelength of the visible light emitted, with the wavelength itself being dependent on the type of atom undergoing the electron excitation.

       The specific atoms which undergo the fluorescence are known as activators. They are usually present as impurities in the normal molecular structure of the mineral, but sometimes are an intrinsic part of the mineral's composition. In fluorescent minerals, very often the activators are cations, which are atoms or molecules which carry a net positive charge (due to the loss of one or more electrons, each of which display a negative charge). For example, the activator which causes the bright red fluorescence of calcite is the manganese cation, Mn⁺². The "Mn" is the chemical symbol for the element manganese, and the "+2" indicates a manganese atom which has lost two electrons and therefore has a net positive charge. A cation which has lost two electrons is also referred to as divalent; three electrons, trivalent; four, quadrivalent, etc. Activators can also sometimes be anions (containing a net negative charge).

This large specimen of willemite (fl green) and calcite (fl red/orange) measures 6"x4"x3" and weighs 5 lbs. In some cases a mineral specimen will continue to emit visible light for a period of less than a second to several minutes or more after the UV light source is taken away, with the luminosity gradually fading away. This is known as phosphorescence, and occurs because the excited electrons are slow in returning to their original electron shells.

       Fluorescent minerals respond best to either short-wave UV light, which has a wavelength of 254 nanometers (nm), or long-wave UV, at 366nm. Some minerals may fluoresce under both wavelengths with the same or a similar color, while some may show different colors under each. Most respond best to only one of the two.

Ozone is generated naturally by short-wave solar ultraviolet radiation, and appears in our upper atmosphere (ozonosphere) in the form of a gas. Ozone also may be produced naturally by passing an electrical discharge - such as lightning - through oxygen molecules. Lightning is a perfect example of making an abundance of O3 to purify the earth's atmosphere Nature's way. Most of us have noticed the clean, fresh smell in the outdoor air after a thunderstorm, or the way clothing smells after it's been dried outside on a clothesline in the sun.

Oxygen, as we know, has two atoms. High voltage, as from lightning, breaks these two atoms apart. Quickly, these atoms hop back together in threes {O3}. Confused, these atoms do not like this arrangement and want desperately to dissolve this uncomfortable trio. So as this O3 molecule floats in the air, when one of the atoms spots a contaminant molecule to attach itself to, it breaks away from the other two atoms. To its surprise, this attachment is actually an attack on the contaminant and creates a microscopic explosion. Both the contaminant and the atom are destroyed. This leaves the other two atoms behind as pure oxygen {O2} without the presence of the contaminant. The explosion changes the contaminant into carbon dioxide and hydrogen, which we can breathe.

Should the O3 molecule not find a contaminant in its environment, it will attack itself to change its configuration of O3 back to O2 (normal oxygen) in 20 to 30 minutes at room temperature and normal humidity.

Short-wave solar ultraviolet radiation - ultraviolet light - is another method used by many air purifier manufacturers. When ultraviolet light rays collide with a contaminant such as carbon monoxide (CO) and nitrogen oxides (NO2 and N2O) in the presence of oxygen (O2), ozone is produced.

Ozone reacts with and oxidizes pollutants it encounters, rendering them harmless, while also removing odors. O3 loses one of its oxygen molecules in this oxidation process, causing it to revert back to oxygen, leaving behind pure, fresh air. Ozone can be effective against chemical sources, bacteria, mold, odors, etc. Once a pollutant is oxidized by ozone, it is no longer toxic, allergenic, or odor causing. As a result, even if an oxidized contaminant remains in the air and is inhaled, it has no negative effect. Microorganisms (such as mold spores or bacteria) that have been exposed to ozone are no longer able to reproduce, which causes their numbers to quickly diminish.

Eye protection must be used when working with short-wave , mid-wave and longtime exposure to longwave UV light sources. Damage to the eyes occurs from exposure to the shorter wavelengths of ultraviolet, known as UV-B (280-315nm) and UV-C (280nm and below). Damage occurs here in the form of photokeratitis (inflammation of the cornea), conjunctivitis, inflammation of the conjunctiva and retinal lesions. The first two being colloquially known as "welder's flash" and "snow blindness."