Lyman-alpha line


Lyman-alpha line

In physics, the Lyman-alpha line is a spectral line of hydrogen, or more generally of one-electron ions, in the Lyman series, emitted when the electron falls from the n = 2 orbital to the n = 1 orbital, where "n" is the principal quantum number. In hydrogen, its wavelength of 121.6 nanometres, corresponding to a frequency of 2.47 × 1015 hertz, places the Lyman-alpha line in the far ultraviolet part of the electromagnetic spectrum.

Because of fine structure perturbations, the Lyman-alpha line splits into a doublet. Specifically, because of the electron's spin-orbit interaction, the stationary eigenstates of the perturbed Hamiltonian must be labeled by the "total" angular momentum "j" of the electron (spin plus orbital), not just the orbital angular momentum l. In the n = 2 orbital, there are two possible states, j = 1/2 and j = 3/2, resulting in a spectral doublet. The j = 3/2 state is of higher energy (less negative) and so is energetically farther from the n = 1 orbital to which it is transitioning. Thus, the j = 3/2 state is associated with the more energetic (shorter wavelength) spectral line in the doublet.

A K-alpha or Kα line analogous to the Lyman-alpha line for hydrogen, occur in the high-energy induced emission spectra of all chemical elements, since it results from the same electron transition as in hydrogen. The equation for prediction of the frequency of this line (usually in the X-ray range for heavier elements), uses the same base-frequency as Lyman-alpha, but modified by a (Z-1)² factor to account for differing atomic numbers (Z) between elements, and is expressed as Moseley's law. The Lyman-alpha line and the rest of the hydrogen Lyman spectral series are most simply described by the empiric Rydberg equation and semi-classic Bohr model of the atom.

ee also

*Lyman-alpha blob
*Moseley's law
*Lyman series
*Bohr model


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Lyman alpha line — or Lyman alpha line, a line of hydrogen in the extreme ultraviolet range of the emission spectrum of the sun, representing a large part of the sun s ultraviolet radiation …   Useful english dictionary

  • Lyman-alpha line — or Lyman alpha line, a line of hydrogen in the extreme ultraviolet range of the emission spectrum of the sun, representing a large part of the sun s ultraviolet radiation …   Useful english dictionary

  • Lyman alpha emitter — Lyman alpha emitters (LAEs) are a type of distant galaxy that emits Lyman alpha radiation. They are extremely distant and becauce of the finite travel time of light they are glimpses of the past history of the universe. They are thought to be the …   Wikipedia

  • Lyman alpha — Lyman alpha, or Ly|man al|pha «LY muhn AL fuh», adjective. of or having to do with the Lyman alpha line. ╂[< E. M. Lyman, born 1910, American physicist] …   Useful english dictionary

  • Lyman-alpha blob — A Lyman alpha blob (LAB) is a huge concentration of a gas emitting the Lyman alpha emission line. The Lyman alpha emission line is produced by recombination of electrons with ionized hydrogen atoms. LABs are some of the largest known individual… …   Wikipedia

  • Lyman-alpha forest — In astronomical spectroscopy, the Lyman alpha forest is the sum of absorption lines arising from the Lyman alpha transition of the neutral hydrogen in the spectra of distant galaxies and quasars.These absorption lines result from intergalactic… …   Wikipedia

  • Lyman series — In physics, the Lyman series is the series of transitions and resulting emission lines of the hydrogen atom as an electron goes from n ge; 2 to n = 1 (where n is the principal quantum number referring to the energy level of the electron). The… …   Wikipedia

  • H-alpha — In physics and astronomy, H alpha, also written Hα, is a specific emission line created by hydrogen at 6562.8 Angstroms.According to the Bohr model of the atom, electrons exist in quantized energy levels surrounding the atom s nucleus. These… …   Wikipedia

  • K-alpha — energy between the electron spin and the orbital momentum of the 2p orbital. K alpha is typically by far the strongest X ray spectral line for an element bombarded with energy sufficient to cause maximally intense X ray emission.The analogous K… …   Wikipedia

  • List of Alpha Phi Alpha brothers — The list of Alpha Phi Alpha brothers (commonly referred to as Alphas cite web |url=http://www.union.arizona.edu/csil/greek/chapters/view.php?id=39 |title=Arizona Student Unions |work=Fraternity and sorority programs |publisher=University of… …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.