Why can't a photon transfer all its energy to a free electron?

[ajl1989]

Why is it that a photon can't transfer all its energy to a free electron?

 

[jtbell]

It's imposible to conserve both energy and momentum in such a process. You need another particle or object in order to do this.

 

[lightarrow]

It's not the same thing, but there is a classical analogue of that fact: a ball of mass m cannot transfer all its kinetic energy to a ball of mass M=/=m.

 

[Bob S]

The only way for a photon to interact with a free electron (other than photoproduction at very high energies) is via Compton scattering.

 

[ajl1989]

Ok, I've got it. This explains it really well: http://74.125.95.132/search?q=cache...can't+absorb+photon&cd=1&hl=en&ct=clnk&gl=us"