Lyman Series
The hydrogen spectral series resulting from electron transitions dropping from higher excited states down to the ground state (n=1).
Governing formula
1 / λ = R_H (1 / 1² - 1 / n_i²), n_i = 2, 3, 4...
SI unit
Ultraviolet Wavelengths (nm)
In depth
Because transitions drop to the lowest energy ground state (n=1), energy changes are large, placing Lyman series emission lines entirely in the ultraviolet region.
Examples in the real world
Lyman-alpha forest absorption lines in quasar spectra used by astronomers to probe intergalactic hydrogen gas distribution.