According to my textbook dense gases, solids and liquids have continuous emission spectra, however, it doesn't explain why this is at all. My theory is that this has something to do with inter-atomic electron transfers, perhaps. However, the only thing about this that concerns me is that this would result in chemical reactions, and as far as I know even dense gases don't react spontaneously. this answer on why moving particles emit energy sort of answers my question. The quote below is an excerpt from the first answer on that page.

these bonds are quantum mechanical, that means that there exist solutions of the Schrodinger equation with energy levels from ground state to continuum, one can model them as repeated over all the mass of the solid , liquid and gas. The unfilled energy levels are close to each other in energy and the continuum of n=infinity ( the radial quantum number).

However, I'm unable to understand how a physical forcethe van der waal force, has any bearing on something that's (maybe) due to electrons being moved between energy levels.

  • $\begingroup$ Also, please try to keep it a bit simple as I'm still in high school. So I dont know too much qunatum theory. $\endgroup$ Sep 17, 2022 at 15:41
  • $\begingroup$ Yes, thanks! So essentially, intermoleculr electron transfers take place, right? $\endgroup$ Sep 18, 2022 at 17:11

1 Answer 1


See: Kirchhoff's Laws and Spectral Analysis

Hot and dense gases/solids will radiate a continuous black-body spectrum according to its temperature. Continuity is an inherent property of black-body radiation according to Planck's Law.

So essentially when something is hot and dense enough, its emission spectrum will be continuous and defined by its temperature.

  • 1
    $\begingroup$ Black body radiation isn't a mechanism. $\endgroup$
    – ProfRob
    Sep 18, 2022 at 16:51

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