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This is a list of sources of light, the visible part of the electromagnetic spectrum.Light sources produce photons from another energy source, such as heat, chemical reactions, or conversion of mass or a different frequency of electromagnetic energy, and include light bulbs and stars like the Sun. Reflectors (such as the moon, cat's eyes, and mirrors) do not actually produce the light that ...
The frequencies of light that an atom can emit are dependent on states the electrons can be in. When excited, an electron moves to a higher energy level or orbital. When the electron falls back to its ground level the light is emitted. Emission spectrum of hydrogen. The above picture shows the visible light emission spectrum for hydrogen. If ...
Cryoluminescence, the emission of light when an object is cooled [6] (an example of this is wulfenite) Photoluminescence, a result of the absorption of photons Fluorescence, traditionally defined as the emission of light that ends immediately after the source of excitation is removed. As the definition does not fully describe the phenomenon ...
Emission can be spontaneous, as in light-emitting diodes, gas discharge lamps (such as neon lamps and neon signs, mercury-vapor lamps, etc.) and flames (light from the hot gas itself—so, for example, sodium in a gas flame emits characteristic yellow light).
Immediate photon emission is called fluorescence, a type of photoluminescence. An example is visible light emitted from fluorescent paints, in response to ultraviolet . Many other fluorescent emissions are known in spectral bands other than visible light. Delayed emission is called phosphorescence. [35] [36]
If emission leaves a system in an excited state, additional transitions can occur, leading to atomic radiative cascade. For example, if calcium atoms a low pressure atomic beam are excited by ultraviolet light from their in the 4 1 S 0 ground state to the 6 1 P 1 state, they can decay in three steps, first to 6 1 S 0 then to 4 1 P 1 and finally ...
Albert Einstein's stimulated emission theory has been validated by large amounts of light, but never before by individual photons—until now. Scientists Finally Manipulate Quantum Light ...
The active materials are generally semiconductors of wide enough bandwidth to allow the exit of the light. The most typical inorganic thin-film EL (TFEL) is ZnS:Mn with yellow-orange emission. Examples of the range of EL material include: Powdered zinc sulfide doped with copper (producing greenish light) or silver (producing bright blue light)