stylistic:tone, structural:scholar_edition, information:extraction
Electron–electron bremsstrahlung

One mechanism, considered important for small atomic numbers Z {\displaystyle Z}, is the scattering of a free electron at the shell electrons of an atom or molecule. Since electron–electron bremsstrahlung is a function of Z {\displaystyle Z} and the usual electron-nucleus bremsstrahlung is a function of Z 2 {\displaystyle Z^{2}}, electron–electron bremsstrahlung is negligible for metals. For air, however, it plays an important role in the production of terrestrial gamma-ray flashes.