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Where does the information about the direction of the emission of the Photoelectron come from? Does it get it from the incoming Photon? I have seen a picture on wikipedia-page of the photoelectric effect, where it almost looked like if the angle of the emission of the Photoelectrons were the same as the angles from the incoming Photons. Is there some "law" which describes why and how the Photoelectrons are emitted at a certain angle like there is for the reflection of light when it hits a reflecting surface in optics?

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  • $\begingroup$ Why the deselection? $\endgroup$ Commented May 28, 2019 at 4:44

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The direction of emission of photoelectrons during the photoelectric effect is random. It is as per QM, all about probabilities.

When you are comparing it to a mirror image, that is not correct. A mirror image is caused by elastic scattering.

When a photon interacts with an atom, three things can happen:

  1. elastic scattering, the photon keeps its energy and changes angle

  2. inelastic scattering, the photon keeps part of its energy and changes angle

  3. absorption, the photon gives all its energy to the atom

A mirror image is built by 1., elastic scattering, that is the only way to keep the energy and phase of the photons.

The photoelectric effect is 3., absorption, when the energy of the photon is transferred to the atom and the electron gets kicked off, because the photon's energy level is enough to reach the work function of the electron.

The angle of the kicked off electrons is random.

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  • $\begingroup$ I wanted to make things clear: I recently stumbled upon an article about X-ray photoelectron spectroscopy and there (I think) it said that the direction in which the Photoelectrons are emitted is parallel to the vector of the electric field of the incoming photon. $\endgroup$ Commented May 28, 2019 at 4:56
  • $\begingroup$ physics.stackexchange.com/questions/119470/… in this Answer (I think) it says that the most propable angle ist perpendicular to the incoming Photon so according to that it shouldn't be completely random, should it? $\endgroup$ Commented May 28, 2019 at 15:27
  • $\begingroup$ @Dinkelberg you are talking about the initial electron. That goes into the body of the metal, all following electrons that do get kicked off (outside the metal), and are visible and make up the visible part of the photoelectric effect, are random in direction because: "The reason for this is because the initial photoelectron is emitted travelled down into the body of the metal. For the photoelectron to escape it has to backscatter off other electrons in the metal and ricochet back to the surface without losing so much energy it can no longer escape." $\endgroup$ Commented May 28, 2019 at 15:58
  • $\begingroup$ @Dinkelberg Please see here: physics.stackexchange.com/a/259538/132371 $\endgroup$ Commented May 28, 2019 at 15:58
  • $\begingroup$ Thank you very much for making things clear! That post helped a LOT. $\endgroup$ Commented May 28, 2019 at 19:03

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