The New Cosmos pp 137-151 | Cite as

Spectra and Atoms: Thermal Excitation and Ionization

  • Albrecht Unsöld
Part of the Heidelberg Science Library book series (HSL)


After important pioneering work by N. Lockyer, in the year 1920 M. N. Saha’s Theory of thermal excitation and ionization led to the interpretation of stellar spectra and their classification. It rests essentially upon the quantum theory of atoms and their spectra developed by N. Bohr, A. Sommerfeld and others from 1913 onwards. Here we briefly recall the fundamentals without their full derivation:


Angular Momentum Statistical Weight Orbital Angular Momentum Neutral Atom Total Angular Momentum 
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Spectra and Atoms: Thermal Excitation and Ionization

  1. Condon, E. U., and G. H. Shortley: The theory of atomic spectra. Cambridge Univ. Press 1963.MATHGoogle Scholar
  2. Griem, H. R.: Plasma spectroscopy. New York: McGraw-Hill 1964.Google Scholar
  3. Herzberg, G.: Atomic spectra and atomic structure New York: Dover.Google Scholar
  4. Moore, Ch. E.: A multiplet table of astrophysical interest,1959; and Atomic energy levels (several volumes, 1949 onwards). Washington: Nat. Bureau of Standards.Google Scholar

Copyright information

© Springer-Verlag New York Inc. 1969

Authors and Affiliations

  • Albrecht Unsöld
    • 1
  1. 1.Institute for Theoretical Physics and University ObservatoryKielGermany

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