mathman said:Resonance?
wdlang said:the higher the energy of the photon, the more powerful it can ionize an atom
but why then the absorption cross section decreases with the photon energy?
ZapperZ said:You need to learn to provide references.
Zz.
wdlang said:
ZapperZ said:<Sigh>
Please cite specifically where it says "... absorption cross section decreases with the photon energy..."
Zz.
wdlang said:see Cross section
ZapperZ said:That is core-level photoemission. It is no longer the same "photoelectric" effect that is characterized by the Einstein equation. Notice the energy of the photon being used. The standard photoemission is done using predominantly visible to UV light that probes the conduction band, not core levels.
BTW, as someone who has done photoemission spectroscopy extensively, I would use this particular entry in Wikipedia as the poster child why someone should NOT use Wikipedia to learn from.
Zz.
wdlang said:i know this
i have in mind the photoelectric effect of atoms not metals
wdlang said:not a resonance
The photoelectric cross section is a measure of the likelihood of a photon interacting with an atom or molecule and causing the ejection of an electron. As the energy of the photon increases, it is more likely to pass through the atom without interacting with it. This is because the energy of the photon is directly related to its frequency, and higher frequencies correspond to shorter wavelengths. Shorter wavelengths can pass through atoms more easily, making it less likely for the photon to interact with the atom and cause the photoelectric effect.
The energy of a photon and its photoelectric cross section are inversely proportional. As the energy of the photon increases, the photoelectric cross section decreases, and vice versa. This relationship is due to the fact that higher energy photons have shorter wavelengths, which make it easier for them to pass through atoms without interacting with them.
The atomic structure plays a significant role in determining the photoelectric cross section. Atoms with more tightly bound electrons will have a higher photoelectric cross section compared to atoms with loosely bound electrons. This is because the more tightly bound electrons require a higher energy photon to overcome the binding energy and cause the photoelectric effect.
Besides the energy of the photon, the atomic number and density of the material can also affect the photoelectric cross section. Materials with a higher atomic number (more protons in the nucleus) will have a higher photoelectric cross section because the positively charged nucleus exerts a stronger pull on the electrons, making them more tightly bound. Additionally, a higher density of atoms in a material will increase the likelihood of a photon interacting with an atom and causing the photoelectric effect.
The photoelectric cross section is a useful tool for studying the properties of materials. By measuring the energy and intensity of photons that pass through a material, we can determine its photoelectric cross section and gain insight into its atomic structure and composition. This information can be used to identify unknown materials, monitor changes in a material's composition over time, and even design new materials with desired properties.