Fluorescent Materials

Fluorescent materials, also known as fluorophores, emit either visible or invisible light when irradiated with a shorter wavelength, such as ultraviolet rays and X-rays. Once the source of irradiation is removed, the fluorescence effect ceases, and the emission of shorter wavelengths stops. In the daylight the emitted wavelengths have a white color owing to the fluorescence, which turns into intensive fluorescent color when excited by ultraviolet irradiation.

Principle

• The phenomenon of fluorescence is an optical property of fluorescent materials. When the wave packets of photons of a certain wavelength are irradiated on a fluorescent material, its molecules absorb the photons and then emit photons of comparatively longer wavelengths. The energy difference of photons (absorbed and emitted) transforms into vibration energy or heat energy.

Examples

• There are several types of amber and calcite that fluoresce on irradiation by shortwave ultraviolet rays. The Hope Diamond, emeralds, and rubies emit red fluorescence on irradiation by shortwave UV rays. The fluorescent properties of crude oil are used in oil exploration drilling. For examples, heavy oils fluoresce in dull brown color and tar in bright yellow color. Some organic liquids also show fluorescent properties, such as the mixture of anthracene in toluene or benzene fluoresces on irradiation by ultraviolet or gamma rays.

Fluorescent Lighting

• Light sources consisting of fluorescent material do not emit as much waste heat as emitted by other kinds of light sources such as halogen bulbs and incandescent bulbs. Most fire incidents associated with a fluorescent light source are due to halogen bulbs. Even incandescent bulbs are riskier than fluorescent bulbs as far as fire incidents are concerned. This is because the two light sources, halogen and incandescent bulbs, emit more waste heat than other fluorescent bulbs do.

Naming

• The term "fluorescence" is derived from the mineral fluorite, which is one of the strongest fluorescent materials. Its primary composition is calcium fluoride. The reason for the naming of fluorescence after this mineral could be because of its discovery as the first material that emits light on excitement by some kind of irradiation.

Applications

• There are various applications of fluorescent materials. Fluorescence lighting has become a common phenomenon. It is considered to be more of an energy saver by compared to incandescent technology. Fluorescent light is used both commercially and industrially. Analytical chemistry and biochemistry have also taken advantage of fluorescent materials in tagging molecules. Fluorescent tagging is applied for determining the position, metabolic path, and formation of several biological molecules and living structures (e.g., cells and antibodies).