What fluoresces in UV?
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Fluorescence in UV Light
Fluorescence under ultraviolet (UV) light is a phenomenon in which certain substances absorb UV light and then emit it almost instantaneously. This effect is caused by the excitation of electrons in the molecules of these substances, which then emit light as they return to their ground state. This unique property is utilized in various fields such as forensic science, mineralogy, and biological research.
Common Examples of Fluorescent Substances
- Minerals - Many minerals fluoresce under UV light, with fluorite, calcite, and willemite being notable examples.
- Biological materials - Chlorophyll in plants, jellyfish, and some bacteria show fluorescence.
- Man-made materials - Highlighters, certain dyes, and fluorescent bulbs.
- Banknotes and official documents - To prevent forgery, many currencies and official documents contain fluorescent security features.
How Fluorescence Works
When UV light strikes a fluorescent substance, its molecules absorb the energy and become excited. This excited state is unstable, and electrons quickly drop back to their lower energy level, releasing energy in the form of visible light. The color of the emitted light is characteristic of the substance and is often different from the color of the absorbed UV light.
Applications of Fluorescence
- Science and Research: Fluorescent markers are used in microscopy and cellular biology to highlight structures within cells.
- Mineralogy: Geologists use UV lamps to identify minerals in the field.
- Security: Fluorescent features in banknotes and documents help in their authentication.
- Art and Entertainment: Fluorescent paints are used in art installations and entertainment venues for dramatic effects.
In conclusion, the phenomenon of fluorescence under UV light showcases the interaction between light and matter, with wide-ranging applications from scientific research to security measures.