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astronomical technique > spectrometry > Lyman-alpha line

Preferred term

Lyman-alpha line  

Definition

  • The Lyman-alpha line, typically denoted by Ly-α, is a spectral line of hydrogen (or, more generally, of any one-electron atom) in the Lyman series. It is emitted when the atomic electron transitions from an n = 2 orbital to the ground state (n = 1), where n is the principal quantum number. In hydrogen, its wavelength of 1215.67 angstroms (121.567 nm or 1.21567×10⁻⁷ m)), corresponding to a frequency of about 2.47×10¹⁵ Hz, places Lyman-alpha in the ultraviolet (UV) part of the electromagnetic spectrum. More specifically, Ly-α lies in vacuum UV (VUV), characterized by a strong absorption in the air. (Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/wiki/Lyman-alpha_line)

Broader concept

Entry terms

  • Lyα line

In other languages

URI

http://data.loterre.fr/ark:/67375/MDL-BL092VG4-L

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