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In quantum mechanics, an absorption band is a range of wavelengths, frequencies or energies in the electromagnetic spectrum that are characteristic of a particular transition from initial to final state in a substance. According to quantum mechanics, atoms and molecules can only hold certain defined quantities of energy, or exist in specific ...
Line-of-sight propagation is a characteristic of electromagnetic radiation or acoustic wave propagation which means waves can only travel in a direct visual path from the source to the receiver without obstacles. [ 1] Electromagnetic transmission includes light emissions traveling in a straight line. The rays or waves may be diffracted ...
The zero-phonon line is located at a frequency ω’ determined by the intrinsic difference in energy levels between ground and excited state as well as by the local environment. The phonon sideband is shifted to a higher frequency in absorption and to a lower frequency in fluorescence. The frequency gap Δ between the zero-phonon line and the ...
A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules. These "fingerprints" can be compared to the previously collected ones ...
The name diffuse interstellar band, or DIB for short, was coined to reflect the fact that the absorption features are much broader than the normal absorption lines seen in stellar spectra. The first DIBs observed were those at wavelengths 578.0 and 579.7 nanometers (visible light corresponds to a wavelength range of 400 - 700 nanometers).
Electronic properties of graphene. Sigma and pi bonds in graphene. Sigma bonds result from an overlap of sp 2 hybrid orbitals, whereas pi bonds emerge from tunneling between the protruding p z orbitals. For clarity, only one p z orbital is shown with its three nearest neighbors. Graphene is a semimetal whose conduction and valence bands meet at ...
A spacetime diagram is a graphical illustration of locations in space at various times, especially in the special theory of relativity. Spacetime diagrams can show the geometry underlying phenomena like time dilation and length contraction without mathematical equations. The history of an object's location through time traces out a line or ...
Neumann lines. Neumann lines, or Neumann bands, are fine patterns of parallel lines seen in cross-sections of many hexahedrite iron meteorites in the kamacite phase, although they may appear also in octahedrites provided the kamacite phase is about 30 micrometres wide. They can be seen after a polished meteorite cross-section is treated with acid.