It has been suggested that this article or section be merged with frequency spectrum. (Discuss)

An energy spectrum is a distribution of energy among a large assemblage of particles. For any given value of energy, it determines how many of the particles have that much energy. The particles may be atoms or phonons in a solid, electrons in a piece of conducting material, or photons flying through space. Wikipedia does not have an article with this exact name. ... In mathematics, physics and signal processing, the frequency spectrum is a representation of a signal or other function in terms of frequency (in the frequency domain). It is the projection of the function onto a set of sinusoidal basis functions. ... Properties For alternative meanings see atom (disambiguation). ... A phonon is a quantized mode of vibration occurring in a rigid crystal lattice, such as the atomic lattice of a solid. ... A solid is a phase of matter, characterized by resistance to deformation and changes of volume. ... Properties The electron is a subatomic particle. ... For the Science Fiction weapon, as seen in Star Trek, see Photon torpedo. ...

In the particular case of photons, an energy spectrum distributes photons along the electromagnetic spectrum (some photons are visible light, some are infrared, some are x-rays, etc.) Analysis of spectra of light emitted, transmitted or reflected by objects can reveal much about their fundamental properties. The electromagnetic spectrum is the range of all possible electromagnetic radiation. ... The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... A spectrum analyzer is a device used to examine at the spectral composition of some electrical, acoustic or optical waveform. ...