Trigger the emission of light by an atomic electron

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Discussion Overview

The discussion centers on the mechanisms that trigger an atomic electron to lose energy by emitting a photon. It explores various phenomena including stimulated emission, spontaneous emission, and the underlying quantum mechanics involved in these processes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant inquires about the cause-and-effect relationship behind an atomic electron losing energy through photon emission, contrasting it with the absorption process.
  • Another participant suggests that stimulated emission is a key mechanism involved.
  • A different viewpoint is presented, indicating that spontaneous emission, such as that from radioactive nuclei, also plays a role in photon emission.
  • One participant elaborates on the coupling of an electron to different energy levels when a photon interacts with it, discussing the probabilities of absorption versus stimulated emission based on transition probabilities.
  • The same participant mentions that spontaneous emission can be understood through quantum electrodynamics (QED) and introduces concepts like zero point energy and the quantization of the electromagnetic field.
  • A participant questions whether classical physics provides any explanations for spontaneous emission phenomena.
  • Another participant responds that classical physics does not adequately explain spontaneous emission, noting the empirical nature of the Einstein A coefficient related to spontaneous emission probabilities.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms of photon emission, with some emphasizing stimulated emission and others highlighting spontaneous emission. There is no consensus on whether classical physics can explain these phenomena.

Contextual Notes

Participants acknowledge limitations in classical and semi-classical treatments of spontaneous emission, indicating unresolved aspects in the understanding of these processes.

afcsimoes
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What does trigger the phenomenon of an atomic electron losing energy through the issue of a photon?
(I know how an atomic electron absorbs light and changes to a more energetic level but I never read an explanation cause-effect of the inverse)
 
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Stimulated emission?
 
blue_leaf77 said:
Stimulated emission?
Yes but not only. I think also in the natural expontaneous emission, like the emissions of a radioactive nucleous.
 
When a photon comes, it actually couples the electron sitting in a certain level with other levels which are separated from the initial level by about the same amount of energy as the energy of the incoming photon. The result of this coupling may end up as an up transition (absorption where the photon get absorbed) or down transition (stimulated emission where the electron goes down to a lower level emitting another photon of the same energy). Whether the electron will undergo absorption or stimulated emission is determined by the transition probability between the initial level and the other level.
As for spontaneous emission, the proper treatment of this event can be done using quantum electrodynamics (QED). It has to do with zero point energy, when you go deeper in QED you will find that vacuum is not really nothing. By quantizing electromagnetic field, it has been found that the absence of photon doesn't mean the energy is zero, I would say it's almost like the case with quantum harmonic oscillator.
 
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I liked your answer. Than you.
 
To Blue_Leaf77 attention, please:
In Classic Physics are there some explanation to the spontanity of those phenomenons?
 
Not even in classical physics. Even semi-classical treatment of the interaction between EM field and atom cannot satisfactorily explain spontaneous emission. Well there is this so-called Einstein A coefficient which is related to the probability of spontaneous emission and which was invented before the birth QED (I think), but I would say that the treatment was more empirical.
 

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