Fig9_4 Radiative interactions between electrons and protons

Fig9_4 Radiative interactions between electrons and protons

Fig. 9.4 . When an electron moves rapidly and freely outside an atom, it inevitably passes near a proton in the ambient gas. There is an electrical attraction between the electron and proton because they have equal and opposite charge, and this pulls the electron toward the proton. If the interaction is distant, it bends the electron’s trajectory and alters its speed. The electron then emits electromagnetic radiation known as bremsstrahlung from the German word for “braking radiation;” this is also called free-free radiation since the electron remains free and unattached to the proton. In a close encounter, the electron goes into orbit around the proton, forming a hydrogen atom and cascading down through allowed orbital energies. In this case, the electron emits recombination radiation, also known as free-bound radiation.

Copyright 2010, Professor Kenneth R. Lang, Tufts University