Einstein's theory on photoelectric effect

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Discussion Overview

The discussion centers around Einstein's theory of the photoelectric effect, specifically exploring the behavior of electrons when they interact with photons of energy lower than the work function of a material. Participants examine the implications of such interactions and the conditions under which electrons may be emitted.

Discussion Character

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

Main Points Raised

  • One participant questions what happens to an electron when a low-energy photon collides with it, suggesting that the photon may be absorbed, raising the electron to a higher energy level.
  • Another participant proposes that if a low-energy photon gives all its energy to an electron, and before the electron returns to a lower energy state, a second photon strikes it, the electron could potentially gain enough energy to be emitted. This is referred to as multiphoton photoemission.
  • A later reply confirms that multiphoton photoemission is possible but notes the low probability of occurrence due to the short lifetime of the excited state of the electron and the need for a photon that can excite that specific electron.
  • One participant expresses curiosity about the factors influencing photon-electron collisions, particularly regarding energy absorption and the nature of the collision (e.g., head-on versus not).

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specifics of photon-electron interactions, particularly regarding the conditions under which electrons can be emitted and the factors affecting these interactions. Multiple viewpoints are presented without resolution.

Contextual Notes

Participants discuss the limitations of the photoelectric effect model, including the assumptions about energy levels and the conditions necessary for multiphoton processes, without resolving the uncertainties involved.

Who May Find This Useful

This discussion may be of interest to those studying quantum mechanics, particularly the photoelectric effect, as well as individuals exploring the interactions between light and matter in solid-state physics.

agtee
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Hey all,
can anyone answer this question??
according t einstein's theory on photoelectric effect if the photon's energy is less then the work function of the material, electron can not come out...

My question is: what happens when a lower energy(less then work function of a material) collides with electron..?
 
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I should think that most of the time, the photon is absorbed by the electron, raising the electron to a higher energy level. (since we're talking about the photoelectric effect, I guess its right to assume that the material in question has the continuous energy bands characteristic of a solid)
 
yaa so if lower energy photon just gives all of its energy to the electron n just befor that electron comes to its lower energy state again, another photon strikes ti electron n now its energy get higher then it should come out... is it possible?
 
agtee said:
yaa so if lower energy photon just gives all of its energy to the electron n just befor that electron comes to its lower energy state again, another photon strikes ti electron n now its energy get higher then it should come out... is it possible?

What you are describing is called a multiphoton photoemission. It certainly is possible, and this technique has been used to study various materials properties.

However, the probability of this occurring is very small. The electron in the excited state has a very short lifetime (in metals, it is of the order of femtosecond). Furthermore, there has to be a photon that can excite that exact electron. This is why multiphoton photoemission processes are typically done with high powered laser, or at least, with optics that can provide a high photon density per unit area.

In any case, for the typical photoelectric effect, which is a single-photon photoemission process, Einstein's model is still perfectly valid.

Zz.
 
Thanks a lot for your information... my question is solved.
 
One more question: What made einstein state that all of the energy of the photon transfers to the electron during collision... coz there can not be head on collision?
 
compton effect is true but i was asking what are the factors that affects this type of collision, whether it would be head on or not; complete absorption(of energy) or not?
 

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