- Fraunhofer lines
In
physics andoptics , the Fraunhofer lines are a set ofspectral line s named for the German physicistJoseph von Fraunhofer (1787 –1826 ). The lines were originally observed as dark features (absorption line s) in theoptical spectrum of theSun .The English chemist
William Hyde Wollaston was in1802 the first person to note the appearance of a number of dark features in the solar spectrum. In1814 , Fraunhofer independently rediscovered the lines and began a systematic study and careful measurement of thewavelength of these features. In all, he mapped over 570 lines, and designated the principal features with the letters A through K, and weaker lines with other letters [Citation
last = Jenkins | first = Francis A.
last2 = White | first2 = Harvey E.
title = Fundamentals of Optics
edition = 4th
publisher = McGraw-Hill
date = 1981
page = 18
isbn = 0072561912 ] . Modern observations ofsunlight can detect many thousands of lines.It was later discovered by Kirchhoff and Bunsen that each
chemical element was associated with a set of spectral lines, and deduced that the dark lines in the solar spectrum were caused by absorption by those elements in the upper layers of the sun. Some of the observed features are also caused by absorption inoxygen molecules in theEarth's atmosphere .The major Fraunhofer lines, and the elements they are associated with, are shown in the following table:
The Fraunhofer C, F, G', and h lines correspond to the alpha, beta, gamma and delta lines of the
Balmer series ofemission line s of the hydrogen atom. The D1 and D2 lines form the well-known "sodium doublet", the centre wavelength of which (589.29 nm) is given the designation letter "D".Note that there is disagreement in the literature for some line designations; e.g., the Fraunhofer d-line may refer to the
cyan iron line at 466.814 nm, or alternatively to theyellow helium line (also labeled D3) at 587.5618 nm. Similarly, there is ambiguity with reference to the e-line, since it can refer to the spectral lines of both iron (Fe) and mercury (Hg). In order to resolve ambiguities that arise in usage, ambiguous Fraunhofer line designations are preceded by the element with which they are associated (e.g., Mercury e-line and Helium d-line).Because of their well defined wavelengths, Fraunhofer lines are often used to characterize the
refractive index and dispersion properties of optical materials.ee also
*
Abbe number
*Timeline of solar astronomy
*Balmer series References
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Fraunhofer lines — Fraun ho*fer lines prop. n. pl.. (Physics.) The lines of the spectrum; especially and properly, the dark lines of the solar spectrum, so called because first accurately observed and interpreted by Fraunhofer, a German physicist. [1913 Webster] … The Collaborative International Dictionary of English
Fraunhofer lines — [froun′hō΄fər] n. [after Joseph von Fraunhofer (1787 1826), Bavarian optician, who first mapped them accurately] the dark lines visible in the spectrum of the sun or a star … English World dictionary
Fraunhofer lines — Astron. the dark lines of the solar spectrum. [1830 40; named after J. von FRAUNHOFER] * * * In astronomical spectroscopy, dark lines in a star s spectrum caused by selective absorption of its radiation at specific wavelengths by the various… … Universalium
Fraunhofer lines — Fraun·ho·fer lines frau̇n .hōf ər n pl the dark lines in the spectrum of sunlight Fraunhofer Joseph von (1787 1826) German optician and physicist. Fraunhofer was a master theoretical optician as well as an expert maker of glass lenses and… … Medical dictionary
fraunhofer lines — n.pl. the dark lines visible in solar and stellar spectra. Etymology: J. von Fraunhofer, Bavarian physicist d. 1826 * * * ˈfrau̇nˌhōfə(r) noun Usage: usually capitalized F Etymology: after Joseph von Fraunhofer died 1826 Bavarian optician and… … Useful english dictionary
Fraunhofer lines — /ˈfraʊnhoʊfə laɪnz/ (say frownhohfuh luynz) plural noun the dark lines of the solar spectrum. {See Fraunhofer diffraction} … Australian English dictionary
Fraunhofer, Joseph von — • Optician (1787 1826) Catholic Encyclopedia. Kevin Knight. 2006. Fraunhofer, Joseph von Joseph von Fraunhofer … Catholic encyclopedia
Fraunhofer , Josef von — (1787–1826) German physicist and optician Fraunhofer, whose family was in the optical trade, was born in Straubing (now in Germany); he was apprenticed to an optician in Munich after his parents died. He subsequently moved to the Utzschneider… … Scientists
Fraunhofer, Joseph von — ▪ German physicist born March 6, 1787, Straubing, Bavaria [Germany] died June 7, 1826, Munich German physicist who first studied the dark lines of the Sun s spectrum, now known as Fraunhofer lines. He also was the first to use extensively the… … Universalium
Fraunhofer'sche Linien — Die Fraunhoferlinien sind dunkle Linien im Spektrum der Sonne. Solche Linien entstehen dadurch, dass Gase in der Photosphäre der sichtbaren Sonnenoberfläche einen Teil des Sonnenlichts absorbieren. Es handelt sich also um Absorptionslinien. Die… … Deutsch Wikipedia