I made a spectrometer that gives the absorption spectrum, by comparing the before and after readings.

There are lots of information on the emission spectrum of elements, but I need the absorption spectra of each element in the period table of elements.

There must be a formula that given amount of neutrons or electrons of an atom, it gives the absorption spectrum of that atom.

thanks in advance, Pascal

  • 1
    $\begingroup$ Absorption for isolated atoms? Absorption for all molecules? While the absorption spectrum for hydrogen is fairly easy to compute, it gets harder from there on out as multi-electron effects come into play. $\endgroup$
    – Jon Custer
    Aug 3, 2018 at 18:28
  • $\begingroup$ Would this assist you to narrow the length of the answer you desire to receive? $\endgroup$
    – Rob
    Aug 3, 2018 at 18:37
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    $\begingroup$ There must be a formula That assumption is wrong. Atoms are many-body systems and no general closed form solutions are known to these. $\endgroup$ Aug 3, 2018 at 18:52

1 Answer 1


As @Jon Custer said in the comments, there is not a generic formula outside hydrogen (which can be calculated exactly). Even for simple elements like alkali atoms (one valence electron), you need complicated methods to calculate the level structures (see PHYSICAL REVIEW A 83, 052508 (2011) for example).

But if you want just the experimentally measured numbers for absorption spectra, NIST database should be your reference.

  • 1
    $\begingroup$ +1 for referencing NIST! $\endgroup$
    – Gilbert
    Aug 3, 2018 at 18:53
  • $\begingroup$ thank you! that is exactly what I need! Also, thank you Rob for the link about emission and absorption spectrums. The absorption spectrum is the inverse of the emission spectrum! $\endgroup$ Aug 4, 2018 at 17:03

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