What is Fluorescence?
Fluorescence is the emission of light from a substance that has been illuminated by electromagnetic radiation of a different wavelength This phenomenon occurs in a variety of materials including minerals, fabrics, plastics, and even bacteria. It is a form of luminescence, a natural process by which energy is transferred from one form to another through the absorption and emission of electromagnetic radiation. This process has many applications, ranging from art and lighting to scientific analysis.
When a material absorbs energy from radiation of a particular wavelength, a process known as excitation, it may emit light with a different wavelength due to changes in the material’s electronic structure. This emitted light is termed fluorescence. The spectrum of the emitted light will usually differ from that of the absorbed radiation, allowing scientists to identify the type of material or its state of oxidation based on the intensity and color of light emitted.
Fluorescence is also a useful tool in the field of microscopy. By using special filters, scientists can isolate fluorescence light and create images with greater contrast. This technique is called fluorescence microscopy and it is commonly employed in medicine, biology, chemistry, and geology.
Examples of Fluorescence
1. Diamonds: Diamonds have the unique property of fluorescing when exposed to ultraviolet light, making them sparkle even more. This phenomenon is caused by the presence of nitrogen in the diamond. Different colors are produced depending on the type and amount of nitrogen present.
2. Fireflies: Fireflies produce a yellow-green glow as a result of a biochemical reaction in their tail. The reaction occurs as a result of the oxidation of luciferin, a molecule present in the firefly’s tail.
3. Quarts: Fluorescence is extremely common in certain types of quartz, most notably amethyst and citrine. The colors produced by these gems are caused by the presence of trace amounts of impurities, such as iron.
4. Jellyfish: Jellyfish, and other aquatic creatures, contain proteins called aequorin, which produce a blue-green glow in response to calcium ions. These molecules are especially abundant in jellyfish, which is why so many of these creatures appear to glow in the dark.
5. Fluorescent Lights: Fluorescent lights are a common example of the everyday use of fluorescence. The glass tube of these lights contains a gas of mercury vapor, which emits ultraviolet radiation when powered. The inside of the tube is coated with a special material, which absorbs the ultraviolet radiation and then re-emits it in the form of visible light.