Energy absorbed by an electron

  • Context: High School 
  • Thread starter Thread starter sanpokhrel
  • Start date Start date
  • Tags Tags
    Electron Energy
Click For Summary

Discussion Overview

The discussion revolves around the concept of energy absorption by electrons in the context of photon interactions, specifically focusing on the phenomenon of two-photon photoemission. Participants explore the conditions under which electrons can be ejected from a metal surface when exposed to radiation of frequencies below the threshold frequency, as well as the implications of simultaneous photon strikes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether an electron can escape the metal surface if two photons strike it sequentially, with their combined energy meeting or exceeding the work function.
  • Another participant suggests that the scenario described involves a "higher-order process," which is less likely than single-photon excitation, and notes the difficulty in pinpointing exact collision times in quantum systems.
  • A participant identifies the process as two-photon photoemission, discussing its relevance in accelerator physics and citing a published paper on the topic, while also mentioning the lower probability of this process compared to single-photon photoemission due to specific conditions required for the second photon.
  • There is a proposal to model the interaction using a two-level quantum system and time-dependent perturbation theory, acknowledging the challenge posed by the continuum of final states in the photoelectric effect compared to the discrete states in a two-level system.
  • One participant raises a question about the interaction of radiation with protons, inquiring about the energy transfer and potential emission of another photon, which leads to a discussion about whether this topic is relevant to the current thread.

Areas of Agreement / Disagreement

Participants express differing views on the likelihood and conditions of two-photon photoemission, with no consensus reached on the broader implications of photon interactions with protons. The discussion remains unresolved regarding the specifics of these interactions.

Contextual Notes

Participants note limitations related to the modeling of the photoelectric effect and the complexities introduced by the continuum of final states in quantum systems. The discussion also touches on the relevance of certain questions to the main topic.

sanpokhrel
When radiation of frequency less than threshold frequency falls on a surface of metal, it gives energy to the electron and at a instant later another radiation of same frequency strikes the same electron, if the energy of two photon equals or is greater than the work function of the electron in that metal, does the electron get out of the metal surface?

What will happen if those two photon strike the electron at the same time.
 
Physics news on Phys.org
I think that would be something called a "higher-order process", which is significantly less likely than excitation by a single photon. I don't think it's possible to talk about the exact time when a collision happens in a quantum system.
 
sanpokhrel said:
When radiation of frequency less than threshold frequency falls on a surface of metal, it gives energy to the electron and at a instant later another radiation of same frequency strikes the same electron, if the energy of two photon equals or is greater than the work function of the electron in that metal, does the electron get out of the metal surface?

What will happen if those two photon strike the electron at the same time.

This process is called 2-photon photoemission. It is quite common in accelerator physics where photoelectrons are generated by intense laser source. I've even published a paper that dealt with this.

The process has less probability of occurring than single-photon photoemission, beause (i) the 2nd photon has to strike in the same vicinity as as the excited electron and (ii) the 2nd photon has to strike and give off its energy BEFORE that excited electron has decayed back into the Fermi sea.

I've written more about this here:

https://www.physicsforums.com/insights/violating-einsteins-photoelectric-effect-model/

Zz.
 
  • Like
Likes   Reactions: hilbert2 and berkeman
Can this be modeled with a 2-level quantum system, by applying a time-dependent perturbation with a frequency lower than the energy gap between states and calculating the 2nd order time-dependent perturbation theory approximation for the transition probability to the excited state? The main problem would probably be that in the photoelectric effect there's a continuum of final states while in the 2-level system there's only one state of course.
 
hilbert2 said:
Can this be modeled with a 2-level quantum system, by applying a time-dependent perturbation with a frequency lower than the energy gap between states and calculating the 2nd order time-dependent perturbation theory approximation for the transition probability to the excited state? The main problem would probably be that in the photoelectric effect there's a continuum of final states while in the 2-level system there's only one state of course.

It is often modeled as a "Rydberg-type" atom. Read the references that I gave related to this in the link.

Zz.
 
ZapperZ said:
This process is called 2-photon photoemission. It is quite common in accelerator physics where photoelectrons are generated by intense laser source. I've even published a paper that dealt with this.

The process has less probability of occurring than single-photon photoemission, beause (i) the 2nd photon has to strike in the same vicinity as as the excited electron and (ii) the 2nd photon has to strike and give off its energy BEFORE that excited electron has decayed back into the Fermi sea.

I've written more about this here:

https://www.physicsforums.com/insights/violating-einsteins-photoelectric-effect-model/

Zz.
I read your paper. Is there possibility that the radiation will hit the proton. What happens to the energy of photon if it strikes proton. Will it emit another photon by decreasing energy of proton?
 
sanpokhrel said:
I read your paper. Is there possibility that the radiation will hit the proton. What happens to the energy of photon if it strikes proton. Will it emit another photon by decreasing energy of proton?

This is now outside the scope of your own topic, isn't it?

Zz.
 
  • Like
Likes   Reactions: sanpokhrel
ZapperZ said:
This is now outside the scope of your own topic, isn't it?

Zz.
But it would be nice if you would explain.
 
  • #10
sanpokhrel said:
But it would be nice if you would explain.

Create another thread with the appropriate topic and maybe someone might. Otherwise, it would be nice to know if your question has been answered. It's not often that a particular question or thread can be acknowledged to be just that.

Zz.
 

Similar threads

  • · Replies 8 ·
Replies
8
Views
802
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K