In analogy to a classical oscillator you have:

exp(i wt) for shimple harmonic oscillator

exp(i wt)* exp(- qt) for damped oscilator

This means  if you Fourier -transform that  your lines are not delta functions (the FT of exp(iwt), but  have a width, for example Lorentzians (the FT of exp(i wt)* exp(- qt) )

I am not sure what you are asking with the rest of your question and whether you refer to these specific  processes for CV.  But that's what radiation damping normally refers to for atomic processes.

Thanks Dr. Alexiou, Thanks for your answer my question.

I am not sure the notation of the  radiation damping effect, but i think is a quantum effect, not a classical notation, also, this effect  occurrs in the atomic process, such as photorecombination process or photoionization process.

Nevertheless, I also thank you for your reply and give my best wishes to you.

Thank you!

There is a very strong analogy, to say the least between an atomic system and a classical oscillator, namely the atomic wavefunction has a similar 'motion', i.e. time dependence exp(iwt) as the classical simple harmonic oscillator, hence the name. Of course it is a quantum effect, but that does notmean it cannot have a classical time dependence. For instance natural width is a very nontrivial quantum effect, yet it results in a wavefunction with the same time dependence as a damped oscillatr.  From your answer I see that this was a general question of what the term refers to rather than a specific question. Hope it makes more sense now