### Lyman series

(L, Ly, Lyman lines)
(hydrogen series from electrons settling from n > 1 to n = 1)

The Lyman series is the set of emission lines (Lyman lines) from atomic hydrogen gas, due to electrons descending from an electron shell number n greater than 1 down to n = 1, or the analogous absorption lines when absorbed electromagnetic radiation makes electrons do the opposite. It is one of the hydrogen line series, such as the Balmer series and is named after Theodore Lyman. Lines:

• 2 -> 1: 121.6 nm (aka Lyman alpha, Ly-α)
• 3 -> 1: 102.6 nm (aka Lyman beta, Ly-β)
• 4 -> 1: 97.3 nm (etc.)
• 5 -> 1: 95.0 nm
• 6 -> 1: 93.8 nm
• 7 -> 1: 93.1 nm
• 8 -> 1: 92.6 nm
• 9 -> 1: 92.3 nm
• 10 -> 1: 92.1 nm
• 11 -> 1: 91.9 nm
• ...
• infinity -> 1: 91.18 nm (the Lyman limit)

Formula for the wavelengths:

```1/wavelength = RH ( 1 - 1/n² )
```
• wavelength is the wavelength within the Lyman series.
• RH is the Rydberg constant for hydrogen, 1.0973731568160 × 107m-1 = 13.6 eV / hc
• n is the higher electron shell number.
• h - Planck constant.
• c - speed of light in a vacuum.

Photons with wavelength at or shorter than the Lyman limit can ionize any hydrogen atom, and are termed Lyman continuum photons or LyC photons. Such photons are likely to ionize any neutral hydrogen in clouds they pass through, regardless of whether the hydrogen is excited. Cases where photons, e.g., from a galaxy, avoid such absorption (Lyman continuum escape) are of research interest.

Analogous series to the hydrogen Lyman and Balmer (etc.) series, occur in any atom or ion in possession of only one electron, which use the same formula with a different Rydberg constant:

```deuterium Rydberg constant, RD = 1.09707417 × 107
helium-4 Rydberg constant, R4He = 1.09722267 × 107
```

The series names are sometimes used for these as well, e.g., deuterium Lyman series, HE-II Lyman series, deuterium Balmer series, HE-II Balmer series, etc.

(Lyman,hydrogen,line series,lines,spectrum)
http://en.wikipedia.org/wiki/Lyman_series
http://en.wikipedia.org/wiki/Lyman_limit
http://en.wikipedia.org/wiki/Lyman_continuum_photons
WaveLFreqPhoton
Energy

91.18nm3.3PHz14eVbeginLyman series
121.6nm2.5PHz10eVendLyman series

Referenced by pages:
atomic excitation
Balmer jump (BJ)
Balmer series (H)
Balmer-break galaxy (BBG)
Bohr model
Brackett series
hydrogen (H)
Lyman-alpha emitter (LAE)
Lyman-break galaxy (LBG)
Lyman alpha (Ly-α)
Lyman-alpha forest
Paschen series
spectral line
spectral line designation

Index