photo electric effect
It is an all or none phenomenon . In this interaction , the incident photon orbit interacts with the bound electron. At this time a portion of the photon's energy is used to drive the electron (BE = E B ) out of the orbit, and the remaining energy (h𝒗 - E B ) is given to the electron as kinetic energy .
Thus the photon disappears and a photoelectron is generated. Thus the vacancy generated by the electron is filled by the outer shell electron and Characteristic X rays are generated.
As the atomic number of absorber increases, the photoelectric effect increases.
PE ∝ Z 3
That is , the absorption of energy is higher by taking higher Z material . So in radiotherapy, Bones absorb more energy than Soft Tissue and Muscle . So Orthovoltage Therapy for Bone Necrosis to reduce Bone Shielding is | The photoelectric effect is less effective as the photon 's enargy increases , as more electrons behave like free electrons.
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| photo electric effect |
Note
Bound electron
When the energy of the photon is equal to or slightly higher than that of the interating electron, it is called bound or bound electron.
Free electron
When the energy of photon is much higher than the interacting electron, it is called free electron.
