Semi-classical calculation in the binary approximation
Plasma radiation and spectral line profiles

Let's consider the shape of the spectrum emitted by an atom whose initial and final levels are disrupted by collision with another atom. In the Born-Oppenheimer approximation, radial motion can be separated from angular motion. Since angular motion is conserved, only the radial part of the motion is taken into account when calculating the spectrum. Let's take the expression for the line profile in the binary approximation [relation (11) ]: