I am aware that low pressure/density gases produce an emission spectrum as there are specific energy transitions that the electrons can make, emitting certain frequencies of EM waves.
However high pressure gases produce a continuous blackbody body spectrum. I am not sure how it is able to emit the entire range of the EM spectrum if only certain transitions are possible. Could someone please explain this?
Further confusing me, I have read that certain high pressure gases still produce an emission spectrum rather than a continuous spectrum. For example, this is observed for hydrogen gas. Is this true and if so could someone also explain this?
It has been explained to me that as the gas molecules become closer together, due to the Pauli Exclusion Principle, the energy levels slightly change in value, allowing for a full range of electron transitions. However correct if I am wrong, but doesn't the PEP basically states that you can't have more than 2 electrons in an orbital. If that is correct, then how does moving two molecules together violate the PEP.
From a chemistry point of view, the changing of energy levels is due to atomic orbitals forming molecular orbitals which form a continuum as the number of atoms reach millions. This makes much more sense to me. How does this explanation fit in with the explanation using Pauli Exclusion Principle?