Photoelectric effect and metal's delocalised electrons

In summary: Thanks.In summary, photoelectrons are emitted from metals when exposed to x-ray photons. This phenomenon is called the photoelectric effect. It is used to measure the properties of metals. Photoemission techniques have been used on semiconductors and insulators to a certain degree.
  • #1
Glenn G
113
12
Hi all,
With the photoelectric effect is it the 'sea' of free electrons that are ejected if the photons are above threshold frequency (i.e. Conduction band electrons ) rather than valence electrons ? If say very energetic gammas are used then suppose this could knock out valence electrons but guess that is then just normal ionisation events ?
Is this thinking correct?
Would really appreciate any thoughts.
Glenn.
 
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  • #2
If you are going to start exposing metals to say x-ray photons I think you have stepped outside the scope of the PE effect experiment.
 
  • #3
houlahound said:
If you are going to start exposing metals to say x-ray photons I think you have stepped outside the scope of the PE effect experiment.
It seems to only talk about photoelectric effect in connection with metals and not non-metals so that made me think it might be delocalised electrons that are released.
 
  • #5
houlahound said:
If you are going to start exposing metals to say x-ray photons I think you have stepped outside the scope of the PE effect experiment.
Interesting thought thanks for that
 
  • #6
The "standard" photoelectric effect is (i) done on metals and (ii) uses, at most, UV sources. So the photoelectrons emitted are from the conduction band.

Now it doesn't mean that this phenomenon hasn't changed from that. The overall area is now generally known as photoemission spectroscopy, and it encompasses a huge field. This includes x-ray photoemission spectroscopy (XPS). This technique does probe deeper levels of the material which are usually known as core-levels. Here, it no longer just probe the conduction band, but also electrons that still localized to the atoms making up the material.

Photoemission techniques have also been done on semiconductors and insulators to a certain degree. In fact, most high quantum efficiency photocathodes are made of semiconductors.

Zz.
 
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Likes Glenn G and vanhees71
  • #7
That great Zz, I didn't know the link with photoemission. Very interesting. G
 

Related to Photoelectric effect and metal's delocalised electrons

1. What is the photoelectric effect?

The photoelectric effect is a phenomenon where the emission of electrons from a material occurs when it is exposed to light of a certain frequency or higher. This effect was first observed by Heinrich Hertz in 1887 and later explained by Albert Einstein in 1905.

2. How does the photoelectric effect work?

The photoelectric effect works by the absorption of photons (particles of light) by the electrons in a material. If the energy of the photons is high enough, it can transfer its energy to the electrons, allowing them to escape from the material's surface. This process is known as photoemission.

3. What is the role of delocalised electrons in the photoelectric effect?

Delocalised electrons, also known as free electrons, are responsible for the movement of electric charge in a material. In the photoelectric effect, these electrons are the ones that are emitted from the material's surface when it is exposed to light of a certain frequency or higher.

4. How are metals able to exhibit the photoelectric effect?

Metals have delocalised electrons, which are loosely bound to the atoms and can move freely within the material. When light of a certain frequency or higher is shone onto a metal, the delocalised electrons can absorb the photons' energy and be emitted from the material, causing the photoelectric effect.

5. What are the practical applications of the photoelectric effect and delocalised electrons?

The photoelectric effect and delocalised electrons have many practical applications, including photovoltaic cells, where light energy is converted into electrical energy, and photoelectric sensors, which are used in many electronic devices such as cameras and scanners. Delocalised electrons are also crucial in the conduction of electricity in metals, making them essential in electrical wiring and other electronic components.

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