Color and the Spectrum: Ultraviolet
Steve Beeson, Arizona State University


How can ultraviolet light help me?



The nearest high-energy neighbor to visible light is the ultraviolet (UV) region, with energies between about 10 eV and several hundred eVs. This is also very short wavelength radiation, in the range of 4 x 10-8m (4000 Å) to about 6 x 10-8m (600 Å).

The sun is a strong emitter of UV radiation, but fortunately for us, the Earth's atmosphere shields its inhabitants from the sun's harmful UV light. In the upper atmosphere lies the ozone layer, where most of the UV radiation is absorbed. This region of O3 is actually created by the interaction of UV photons with molecular oxygen, O2. The ozone then absorbs other UV photons, re-emitting them as infrared photons, or heat. So the ultraviolet photons can not only harm us, in burning our skin, and causing other skin maladies, but can also help us in that it helps create the atmospheric layer that then blocks out other UV photons.


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Steve Beeson, Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287