What an electron in an atom will do when given more energy

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Discussion Overview

The discussion revolves around the behavior of an electron in an atom when it is supplied with energy that falls between two defined energy levels. Participants explore the implications of providing an electron with 1.9 eV of energy, which is greater than the energy gap to the next level but less than the subsequent gap, and consider various scenarios regarding absorption and excitation.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions whether an electron will absorb the 1.9 eV energy and transition to the second energy level, potentially releasing excess energy as a photon.
  • Another participant suggests that the electron might ignore the incoming photon, indicating a low probability of absorption unless the energy matches the transition energy.
  • A different perspective introduces the concept of an oscillating electromagnetic field, suggesting that an atom can alternate between states due to absorption and stimulated emission when energy does not match exactly.
  • One participant emphasizes the importance of resonance in the absorption of light, noting that energy absorption is more likely when the incoming energy matches the transition energy.
  • Another participant discusses "detuning," explaining that an electromagnetic wave with a frequency that does not match the transition energy can still excite the electron with some probability, but this probability decreases with increased mismatch.
  • There is mention of the semiclassical model and the complexity of analyzing the situation using quantum electrodynamics (QED), with some participants expressing uncertainty about the applicability of QED to the problem.

Areas of Agreement / Disagreement

Participants express differing views on whether the electron will absorb the energy and transition states. There is no consensus on the outcome, as opinions vary on the likelihood of absorption and the effects of detuning.

Contextual Notes

Participants note that the emission and absorption spectra have finite widths, which complicates the understanding of energy transitions. The discussion references specific documents and concepts, indicating a reliance on theoretical models that may not fully resolve the questions posed.

Who May Find This Useful

This discussion may be of interest to those studying atomic physics, quantum mechanics, or anyone exploring the interactions between light and matter at the atomic level.

Ahsan Khan
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Hello all,

I have a question. Consider an electron in a shell of an atom has energy as 1.0ev and in the next shell it energy should be 2.7eV and the further next level energy is let's say 3.1eV. Means an energy gap of 1.7eV is their between first and second level and an energy gap o 2.1 eV is their between first and third level.My question is what happens when energy of 1.9eV which is more than 1.7eV but less than 2.1eV is given to an electron in first level?

Will it aborsb all energy, go to second level and then release the rest of 0.4eV energy?Or will it do not absorb this amount of energy at all? What exactly will the electron do with the energy supplied?

Regards!
Thanks a bunch in advance
 
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If a 1.9 ev photon strikes the electron then it could move to the second level while giving off a .2 ev photon. But I think this is improbable. More likely the electron would just ignore the incoming photon. All of this is my opinion.
 
If you put an atom in an oscillating electromagnetic field where the photon energies do not exactly correspond to a transition energy, the atom will go back and forth between an excited state and the original state because of alternating absorption and stimulated emission.
 
Gene Naden said:
More likely the electron would just ignore the incoming photon. All of this is my opinion.
Thanks Gene Naden giving your opinion and I also think so :) however just need an answer from someone who can answer this with surety not a mere opinion.
 
Well actually I am pretty sure of my answer. The absorption of light by an atom is subject to resonance, which means that it is much more likely to occur if the incoming energy matches the transition energy.
 
Look at the pages 83-85 in this document:

https://www.physik.hu-berlin.de/de/nano/lehre/copy_of_quantenoptik09/Chapter7

The deviation of the photon frequency from the actual atomic transition energy is called "detuning". My previous comment may have been a bit misleading, as actually an EM wave of the exact transition frequency will also cause alternating excitation and de-excitation. The difference is that a detuned wave will never move the atom to a state where it is excited with 100% probability.

This kind of model is only an approximate semiclassical one, though, but trying to solve the problem with QED and Feynman diagrams would be a lot more complicated than the shell model of an atom that you're assuming in the first place, here.
 
hilbert2 said:
Look at the pages 83-85 in this document:

https://www.physik.hu-berlin.de/de/nano/lehre/copy_of_quantenoptik09/Chapter7

The deviation of the photon frequency from the actual atomic transition energy is called "detuning". My previous comment may have been a bit misleading, as actually an EM wave of the exact transition frequency will also cause alternating excitation and de-excitation. The difference is that a detuned wave will never move the atom to a state where it is excited with 100% probability.

This kind of model is only an approximate semiclassical one, though, but trying to solve the problem with QED and Feynman diagrams would be a lot more complicated than the shell model of an atom that you're assuming in the first place, here.
Thanks hilbert2 for the answer with rigorous concepts of QED. Form what Gene Naden endorse and what I could conclude from your post is that the answer to my very question in my first post of this thread is that the electron will do nothing with that energy and will not go to next excited state liberating excess energy.

Am I correct.
 
The elecromagnetic wave with a "mismatched" frequency can excite the electron to a higher energy state with some probability (which becomes smaller when the mismatch increases), at least in the semiclassical model where the EM wave obeys classical electrodynamics and only the atom is treated quantum mechanically. I don't have the skills to analyze this with QED, but I guess there's some process where an atom can capture only a part of the energy of a photon, resulting with the atom in excited state and a lower-frequency photon.
 
ovais said:
Thanks hilbert2 for the answer with rigorous concepts of QED. Form what Gene Naden endorse and what I could conclude from your post is that the answer to my very question in my first post of this thread is that the electron will do nothing with that energy and will not go to next excited state liberating excess energy.

Am I correct.
The emission/absorption spectra have a finite width and it is not clear cut what happens. These lecture notes may help answer your questions.
Laser Cooling of Atoms
https://web.stanford.edu/~rpam/dropoff/Phys041N/lecture6-lasercooling.pdf
 

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