High and low energy photon absorption

In summary, the conversation discussed the absorption of high intensity lasers by (helium cooled) Mono C-silicon at wavelengths of 900-1100 nm and how Ultra-violet and visible light can cause a rise in material temperatures. It was mentioned that silicon is transparent at photon energies below the indirect band gap of Eg=1.1 eV at room temperature. However, there is some absorption below Eg due to thermal effects and at very low temperatures, the larger direct bandgap determines absorption. The conversation also suggested further resources for more detailed information on this topic.
  • #1
Karim Habashy
33
1
Hi All,

Kindly find here 2 questions, i was wondering about:

1) Will (helium cooled) Mono C-silicon be able to absorb a high intensity laser of about 900-1100 nm ?

2) How can Ultra-violet and visible light cause rise in material temperatures.

Thanks.
 
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  • #2
1. That would be IR so it would be surprising if some was not abdorbed.
2. Same way any light increases temperature.
 
  • #3
Silicon is quite transparent at photon energies below the indirect band gap of Eg=1.1 eV at room temperature.
It is an amazing experience to look straight trough a wafer with night vision.
There is absorption below Eg because the valence band is not fully occupied due to thermal effects.
Above Eg phonon assisted transitions occur.
At very low T it is the larger direct bandgap that determines absorption.
Anything at or below red light passes through.
See http://en.wikipedia.org/wiki/Direct_and_indirect_band_gaps#Implications_for_light_absorption
See also
http://refractiveindex.info/?shelf=main&book=Si&page=Vuye-20C
 

Related to High and low energy photon absorption

1. What is high and low energy photon absorption?

High and low energy photon absorption is a phenomenon in which photons, or particles of light, are absorbed by a material. The energy of the photons determines how the material will interact with them. High energy photons are more likely to be absorbed by the material, while low energy photons are less likely to be absorbed.

2. How does high and low energy photon absorption affect materials?

The absorption of high and low energy photons can have different effects on materials. High energy photon absorption can cause changes in the electronic structure of the material, such as exciting electrons to higher energy levels or breaking chemical bonds. Low energy photon absorption may not have as drastic of an effect, but can still cause changes in the material's temperature or physical properties.

3. What factors affect the absorption of high and low energy photons?

The absorption of high and low energy photons can be affected by several factors, including the composition and structure of the material, the intensity and wavelength of the light, and the angle of incidence of the light on the material. These factors can all play a role in determining how much energy is absorbed and how the material will respond.

4. Can high and low energy photon absorption be used for practical applications?

Yes, high and low energy photon absorption has many practical applications. For example, it is used in solar cells to convert sunlight into electricity, in phototherapy for medical treatments, and in spectroscopy to analyze the chemical composition of materials. Understanding and controlling high and low energy photon absorption is essential for developing new technologies and improving existing ones.

5. How is high and low energy photon absorption studied and measured?

High and low energy photon absorption can be studied and measured through various techniques, such as absorption spectroscopy, which measures the amount of light absorbed by a material at different wavelengths. Other methods include photoemission spectroscopy, which measures the energy of electrons emitted from a material after photon absorption, and X-ray absorption spectroscopy, which uses X-rays to study the absorption of high energy photons. These techniques allow scientists to understand the mechanisms and properties of high and low energy photon absorption in different materials.

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