What range of light on the electromagnetic spectrum are produced by the de-excitation of electrons?

Question

When an electron moves from an excited state to its ground state, a photon is emitted, which is the source of light. However, I know that the highest energy form of light, gamma rays, are produced from the relaxation of an excited nucleus instead of excited electrons. I was curious, is every other type of light on the electromagnetic spectrum from radio waves to x-rays produced by the relaxation of electrons, with gamma rays being the exception? Or is it only visible light that is produced by the relaxation of electrons?

Answer 1

I’m going to cheat a little and suggest rather than just considering transitions of electrons between bound states that you can also consider radiation form electrons being accelerated or suddenly stoped. Take a look at bremsstrahlung radiation and I think you can find example of emission from radio waves to at least x-rays.

If you want to consider just transitions between energy levels you could look for some exotic transitions using a spectrometer in vacuum. For example the shortest wavelength mercury transition seems to 744 angstroms. That’s pretty energetic.

In general with atoms you can get emission from electron transitions the deep UV to the near IR. If you consider the vibrations of molecules like CO2 you can get into the far IR or upper part of the terahertz.