Spectral Line

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spectral line

[′spek·trəl ‚līn]
A discrete value of a quantity, such as frequency, wavelength, energy, or mass, whose spectrum is being investigated; one may observe a finite spread of values resulting from such factors as level width, Doppler broadening, and instrument imperfections. Also known as spectrum line.

Spectral Line


a thin line in an optical spectrum. Each such line can be characterized by a certain wavelength λ or frequency v = c/λ, where c is the speed of light. Spectral lines are observed in emission spectra as bright (colored) lines on a dark background and in absorption spectra as dark lines on a bright background. Each spectral line corresponds to a definite quantum transition in an atom, molecule, or crystal. Spectral lines are not strictly monochromatic: each one has a certain width Δλ.

References in periodicals archive ?
If so, it could be possible to observe an absorption line at 3.
Measurement selectivity requires that within the wavelengths analysed, the other substances should have no absorption lines or of negligible amplitudes [3], [4], [11].
27 PHYSICAL REVIEW LETTERS, they present data suggesting that the spacings between absorption lines for several types of atoms 8 to 12 billion years ago were different than they are today.
Previous studies had found a few examples of quasars whose broad absorption lines seemed to have disappeared between one observation and the next.
This data can be displayed through absorption lines and by the relative strength shown, the D/H line can be evaluated.
In the course of observing quasars, astronomers have discovered clouds of hydrogen gas that make their presence known by absorbing some of the quasar's radiation, creating a thicket of absorption lines.
For scientists interested in knowing the atmospheres chemical makeup, the laser offers another important benefit: the ability to measure water vapor whose absorption lines lie next to CO2s absorption lines.
In Fleming's classification, an A star displayed only hydrogen absorption lines in its spectrum, while a B star also displayed prominent Orion lines, named after the absorption lines found in many stars near the Orion constellation and later discovered to come from the element helium.
Scientists at the VU University of Amsterdam and the Max Planck Institute for Radio Astronomy in Bonn used the 100-metre radio telescope in Effelsberg to measure absorption lines of the methanol molecule at a number of characteristic frequencies.