We solved the equation of electron escape probability from the Schrodinger equation, and calculated the emitted electron energy distribution of GaAs photocathodes.

The radiation spectrum for relativistic electron moving along curved spiral curve in plasmas is calculated, and also the formula of total energy emitted by a relativistic electron in vacua is derived.

Normally, the ejected electron will be replaced within the material and a characteristic X-ray will be emitted with an energy that is dependent on the atomic number of the material.