emission spectrum


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emission spectrum:

see spectrumspectrum,
arrangement or display of light or other form of radiation separated according to wavelength, frequency, energy, or some other property. Beams of charged particles can be separated into a spectrum according to mass in a mass spectrometer (see mass spectrograph).
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emission spectrum

A spectrum formed by emission of electromagnetic radiation by matter. Energy has first to be supplied, either as heat (high temperature) or by some other mechanism such as absorption of electromagnetic radiation by the matter or by impact of electrons. The energy raises the atoms or molecules to higher energy levels. In a simple example, the electron in a hydrogen atom may ‘jump’ from its normal orbit to one farther from the nucleus (see hydrogen spectrum). The emission spectrum of hydrogen, or any other emitting material, is formed by transitions from such excited states to lower energy states, the excess energy appearing in the form of photons with characteristic frequencies.

The emission spectrum therefore consists of a specific pattern of narrow peaks – emission lines – that occur at these frequencies. These lines may be superimposed on a continuum, but not necessarily so. Emission lines can occur in stellar spectra if, for example, the star is surrounded by a hot shell of diffuse gas. They also occur, for example, in the spectra of emission nebulae, the interstellar medium (see molecular-line radio astronomy), and quasars. See also absorption spectrum; excitation.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

emission spectrum

[i′mish·ən ‚spek·trəm]
(spectroscopy)
Electromagnetic spectrum produced when radiations from any emitting source, excited by any of various forms of energy, are dispersed.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The value of the normalization wavelength was chosen near the maximum of the emission spectrum. The sum over a specified range of wavelengths in Fig.
J is the overlap integral of the fluorescence emission spectrum of the donor and the absorption spectrum of the acceptor in units [M.sup.-1] [cm.sup.3].
Throughout further processing, aldehydes dominated the emission spectrum.
Hyperspectral imaging is a recent technique that permits quantitative delineation of multiple labels by filtering and measuring the fluorescence emission spectrum of each fluorophore.
Figure 7 gives an example on the spectral match of the emission spectrum of YP[O.sub.4]:Pr and the Germicidal Action Curve.
Since, in practice, the processes (n) and ([n.sup.[dagger]]) occur simultaneously, sidebands with photon energies [hv.sub.anneal] - [nhv.sub.p] and [hv.sub.anneal] + [nhv.sub.p] appear in the emission spectrum. The relationship between the nth order sideband energy and the photon energy [hv.sub.anneal] is the same as that of an nth order Raman scattering process with respect to the zero-phonon line.
The fluorescence emission spectrum after excitation at 275 nm is shown in Figure 2(a) (solid line) as well as the normalized emission spectrum of tryptophan residues (excitation at 290 nm, dotted line) and the emission spectrum of tyrosine residues (dashed line).
The real-time PCR machine illuminates the reaction tube with filtered photons matched to the reporter's excitation wavelength, and uses a detector to "look" for photons at the reporter's emission spectrum. Because of FRET, however, almost all photons released by the reporter dye are captured by the quencher dye, physically tethered at the other end of each probe molecule.
Supply, installation and commissioning of an identification instrument for the atomic emission spectrum required for measuring the heavy metals contents inside the central laboratory.
Several distinguished episodes of energy release which led to the change in the emission spectrum shape are clearly seen in Figure 9.Themaximum time of [dI.sub.SXR]/dt coincides well with the maximum time of the energetic emission at 06:47:10 (see panels (c), (d), and (e)).
The spectrum of polymer light-emitting diodes covered from 490 nm to 690 nm, and full width at half-maximum (FWHM) of emission spectrum was 116 nm (from 504 nm to 620 nm), which was 68 nm for SMOLED (from 500 nm to 568 nm).

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