# EM scattering

Would I be right in saying the difference between Rayleigh and Tomson scattering is that Tomson involves scattering off a free electron, whereas in Rayleigh the incident wave is scattered off a bound nucleus?

Alos are there any other differences in the two scattering processes?

Thanks

## Answers and Replies

One final thing. Are both elastic scattering?

In the classical limit, Thomson scattering is treated as elastic scattering off a single "free" electron; If the electron atomic binding energy is B, and electron rest mass is m0c2, then B << hv << m0c2 for Thomson scattering. It is the classical limit of Compton scattering, which is inelastic. The energy of the scattered photon is given by
(1/hv') -(1/hv) = 1/[m0c2(1-cos{theta})]
which shows that the scattered photon hv' at theta=90 degrees is nearly exactly the same energy as the incident photon hv for UV and soft x-rays (hv ~ 1000 eV).