absorption spectrum

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absorption 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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absorption spectrum

A spectrum that is produced when electromagnetic radiation has been absorbed by matter. Typically, absorption spectra are produced when radiation from an incandescent source, i.e. radiation with a continuous spectrum, passes through cooler matter. Radiation is absorbed (i.e. its intensity is diminished) at selective wavelengths so that a pattern of very narrow dips or of wider troughs – i.e. absorption lines or bands – are superimposed on the continuous spectrum.

The wavelengths at which absorption occurs correspond to the energies required to cause transitions of the absorbing atoms or molecules from lower energy levels to higher levels. In the hydrogen atom, for example, absorption of a photon with the required energy results in a ‘jump’ of the electron from its normal orbit to one of higher energy (see hydrogen spectrum).

The absorption lines (or bands) of a star are produced when elements (or compounds) in the outermost layers of the star absorb radiation from a continuous distribution of wavelengths generated at a lower level in the star. Basically the same elements occur in stars. Since each element has a characteristic pattern of absorption lines for any particular temperature (and pressure) range, there are several different types of stellar spectra depending on the surface temperature of the star. See spectral types. See also emission spectrum.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Absorption Spectrum


the spectrum that results when optical or X-radiation is passed through a substance and is selectively absorbed.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

absorption spectrum

[əb′sȯrp·shən ‚spek·trəm]
A plot of how much radiation a sample absorbs over a range of wavelengths; the spectrum can be a plot of either absorbance or transmittance versus wavelength, frequency, or wavenumber.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
(b) Simulated absorption spectra for W absorber and bare W slab with normally-incident light of x-polarization ([theta] = [phi] = 0, i.e., electric field parallel to the x-axis).
Analyzing the UV-Vis absorption spectra of Figure 4(a) and tests data in Table 2, we can find that the maximum absorption wavelengths of five groups of sample solutions are in the range of 410~430nm, and when [mathematical expression not reproducible], the maximum absorption wavelengths Am has a little small value.
The absorption spectra of all three sensitizers on the Ti[O.sub.2] films exhibited significantly hypsochromic shift and a broader full width at half maximum (fwhm) than absorption spectra measured in CH[Cl.sub.3] due to strong interactions between the dyes and Ti[O.sub.2] surfaces.
Caption: Figure 1: Absorption spectra of surface freshwater from three Karelian lakes, unfiltered (solid lines) and filtered (dashed lines).
Figure 2 shows that the absorption spectra of ASA, DNA, Tm(III), DNA-ASA, DNA-Tm(III), Tm(III)-ASA complex, and Tm(III)-ASA-DNA system at a certain concentration were obtained using a UV-vis spectrometer.
Caption: Figure 6: Near-infrared absorption spectra of ACV ointments, observed to 4000-10000 [cm.sup.-1].
The absorption spectra from 500 nm to 2000 nm at room temperature of 3 at.% Tm, x at.% Y are shown in Figure 2(a).
Huffman, "The infrared and ultraviolet absorption spectra of laboratory produced carbon dust: evidence for the presence of the [C.sub.60] molecule," Chemical Physics Letters, vol.
Absorption spectra of DBM shows broad band with maximum at 343 nm, which is assigned to enolic [pi]-[pi]* transitions of the [beta]-diketone moiety.
In this study, the absorption spectra of PSU (sample 9), PSU-b-PAO-b-PDMS (samples 1-5), and PSU-WAO (sample 6) in 1,2-dichloroethane were recorded at different temperatures and the relative absorbance [A.sub.max]/[A.sup.o] was calculated for each sample (where [A.sub.o] and Amax are the values of maximum absorbance at 20[degrees]C and at a given temperature, t, respectively, when the temperature varies from 25[degrees]C to 75[degrees]C).
Huber, "Coherent potential approximation for the absorption spectra and the densities of states of cubic Frenkel exciton systems with Gaussian diagonal disorder," Physica B: Condensed Matter, vol.
UV-Vis absorption spectra of all synthesized CdSe nanoparticles are shown in Figure 1(a).