Ultraviolet (UV) radiation interacts with different materials in various ways depending on the material’s chemical structure, thickness, and the specific UV wavelength. These interactions can result in absorption, reflection, transmission, or even chemical changes. Here’s a breakdown:
1. Absorption
- Organic materials (e.g. plastics, fabrics, human skin) often absorb UV radiation, especially UV-B and UV-C.
- DNA and proteins absorb UV strongly, particularly around 260 nm, leading to damage like mutations or denaturation.
- Polymers degrade over time when exposed to UV (a process called photodegradation), causing discoloration and brittleness.
2. Transmission
- Glass blocks most UV-B and UV-C but allows some UV-A to pass through.
- Quartz glass can transmit UV-C and is used in UV lamps and scientific equipment.
- Plastic films vary—some allow UV through, while others (like UV-blocking films) are designed to stop it.
3. Reflection
- Metals and polished surfaces (like aluminum or mirrored coatings) reflect UV efficiently.
- White or light-colored surfaces reflect more UV than dark ones, though the reflectivity depends on the surface finish and material.
4. Fluorescence and Phosphorescence
- Some materials absorb UV and emit visible light, a property used in fluorescent paints, inks, and counterfeit detection.
5. Degradation and Chemical Changes
- UV can cause chemical reactions such as ozone formation, bleaching, and polymer breakdown.
- Photovoltaic materials may degrade under prolonged UV exposure, reducing their efficiency.