Which electrons contributed in compton scattering

[Taghi]

Hello all,

Can anyone explain to me which electrons contribute in compton scattering?

-Only free electrons;
-Free electrons and weakly bounded to atoms;
-All atomic electrons and free electrons

According to Klein-Nishina formula, photons scatter with all atomic electrons; becouse the cross-section is proportional to Z. But in some books define Compton scattering with only free or weakly bounded electrons. What is true?

Please send me your idea.

Thanks

Taghi Bayat

 

[jcsd]

Yes, the Compton effect does work with bound electrons but only because the photon energy is much greater than the binding energy between the electron and the solid, so the electron is knocked clean out of the solid.

 

[mathman]

The free electron formula is valid for high energy photons (e.g. gamma rays of the order of 1 Mev or more). When you deal with lower energies, the binding effect is evident and the K-N formula has to be modified.