The lines appear in emission when hydrogen atoms' electrons descend to the fourth energy level from a higher level, and they appear in absorption when the electrons ascends from the fourth energy level to higher levels. These lines lie in the infrared part of the electromagnetic spectrum, with wavelengths ranging from 4.05 micrometres (Brackett-alpha) to 1.46 micrometres (the series limit).

See also

• Bohr model
• H-alpha
• Rydberg formula

References

• Frederick Sumner Brackett, "Visible and infra-red radiation of hydrogen"; Astrophysical Journal, vol. 56, (1922) p.154;

External links

• Brackett series (animation)
• Brackett series