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Here is an illustration of the first series of hydrogen emission lines: The Lyman series. Historically, explaining the nature of the hydrogen spectrum was a considerable problem in physics. Nobody could predict the wavelengths of the hydrogen lines until 1885 when the Balmer formula gave an
The spectral series of hydrogen, on a logarithmic scale. The emission spectrum of atomic hydrogen has been divided into a number of spectral series, with wavelengths given by the Rydberg formula. These observed spectral lines are due to the electron making transitions between two energy levels in an atom.
The Lyman alpha line is the n=2 to n=1 transition of neutral hydrogen, and can be produced copiously by galaxies with young stars. [14] Moreover, Lyman alpha photons interact strongly with neutral hydrogen in intergalactic gas through resonant scattering, wherein neutral atoms in the ground (n=1) state absorb Lyman alpha photons and almost ...
Lyman-alpha, 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 .
The energy of the Lyman-alpha transition is 10.2 eV—this energy is approximately two million times greater than the hydrogen line, and is produced by astrophysical sources such as stars and quasars. Neutral hydrogen absorbs Lyman-alpha photons, and then re-emits Lyman-alpha photons, and may enter either of the two spin states.
The Lyman-alpha forest was first discovered in 1970 by astronomer Roger Lynds in an observation of the quasar 4C 05.34. [1] Quasar 4C 05.34 was the farthest object observed to that date, and Lynds noted an unusually large number of absorption lines in its spectrum and suggested that most of the absorption lines were all due to the same Lyman-alpha transition. [2]
In cosmology, intensity mapping is an observational technique for surveying the large-scale structure of the universe by using the integrated radio emission from unresolved gas clouds. In its most common variant, 21 cm intensity mapping , the 21cm emission line of neutral hydrogen is used to trace the gas.
A hydrogen molecule can absorb a far-ultraviolet photon (11.2 eV < energy of the photon < 13.6 eV) and make a transition from the ground electronic state X to excited state B (Lyman) or C (Werner). Radiative decay occurs rapidly. 10–15% of the decays occur into the vibrational continuum. This means that the hydrogen molecule has dissociated.